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PROC(5)			   Linux Programmer's Manual		       PROC(5)

NAME
       proc - process information pseudo-filesystem

DESCRIPTION
       The  proc filesystem is a pseudo-filesystem which provides an interface
       to kernel data structures.  It is commonly mounted at /proc.   Most  of
       it is read-only, but some files allow kernel variables to be changed.

       The  following  list  describes many of the files and directories under
       the /proc hierarchy.

       /proc/[pid]
	      There is a numerical subdirectory for each running process;  the
	      subdirectory is named by the process ID.	Each such subdirectory
	      contains the following pseudo-files and directories.

       /proc/[pid]/auxv (since 2.6.0-test7)
	      This contains the contents of the	 ELF  interpreter  information
	      passed  to the process at exec time.  The format is one unsigned
	      long ID plus one unsigned long value for each entry.   The  last
	      entry contains two zeros.

       /proc/[pid]/cgroup (since Linux 2.6.24)
	      This  file  describes  control  groups to which the process/task
	      belongs.	For each cgroup hierarchy there is one entry  contain‐
	      ing colon-separated fields of the form:

		  5:cpuacct,cpu,cpuset:/daemons

	      The colon-separated fields are, from left to right:

		  1. hierarchy ID number

		  2. set of subsystems bound to the hierarchy

		  3. control  group  in	 the  hierarchy	 to  which the process
		     belongs

	      This file is present only if the CONFIG_CGROUPS kernel  configu‐
	      ration option is enabled.

       /proc/[pid]/cmdline
	      This holds the complete command line for the process, unless the
	      process is a zombie.  In the latter case, there  is  nothing  in
	      this  file:  that	 is, a read on this file will return 0 charac‐
	      ters.  The command-line arguments appear in this file as	a  set
	      of  strings  separated by null bytes ('\0'), with a further null
	      byte after the last string.

       /proc/[pid]/coredump_filter (since kernel 2.6.23)
	      See core(5).

       /proc/[pid]/cpuset (since kernel 2.6.12)
	      See cpuset(7).

       /proc/[pid]/cwd
	      This is a symbolic link to the current working directory of  the
	      process.	 To  find out the current working directory of process
	      20, for instance, you can do this:

		  $ cd /proc/20/cwd; /bin/pwd

	      Note that the pwd command is often a shell built-in,  and	 might
	      not work properly.  In bash(1), you may use pwd -P.

	      In  a  multithreaded process, the contents of this symbolic link
	      are not available if the	main  thread  has  already  terminated
	      (typically by calling pthread_exit(3)).

       /proc/[pid]/environ
	      This file contains the environment for the process.  The entries
	      are separated by null bytes ('\0'), and there may be a null byte
	      at  the  end.   Thus, to print out the environment of process 1,
	      you would do:

		  $ strings /proc/1/environ

       /proc/[pid]/exe
	      Under Linux 2.2 and later, this file is a symbolic link contain‐
	      ing  the actual pathname of the executed command.	 This symbolic
	      link can be dereferenced normally; attempting to	open  it  will
	      open  the	 executable.  You can even type /proc/[pid]/exe to run
	      another copy of the same executable as is being run  by  process
	      [pid].   In  a  multithreaded process, the contents of this sym‐
	      bolic link are not available if the main thread has already ter‐
	      minated (typically by calling pthread_exit(3)).

	      Under  Linux 2.0 and earlier /proc/[pid]/exe is a pointer to the
	      binary which was executed, and appears as a  symbolic  link.   A
	      readlink(2)  call	 on this file under Linux 2.0 returns a string
	      in the format:

		  [device]:inode

	      For example, [0301]:1502 would be inode 1502 on device major  03
	      (IDE,  MFM,  etc. drives) minor 01 (first partition on the first
	      drive).

	      find(1) with the -inum option can be used to locate the file.

       /proc/[pid]/fd/
	      This is a subdirectory containing one entry for each file	 which
	      the process has open, named by its file descriptor, and which is
	      a symbolic link to the actual file.  Thus, 0 is standard	input,
	      1 standard output, 2 standard error, and so on.

	      For  file descriptors for pipes and sockets, the entries will be
	      symbolic links whose content is the file type with the inode.  A
	      readlink(2) call on this file returns a string in the format:

		  type:[inode]

	      For  example, socket:[2248868] will be a socket and its inode is
	      2248868.	For sockets, that inode	 can  be  used	to  find  more
	      information in one of the files under /proc/net/.

	      For  file	 descriptors  that  have no corresponding inode (e.g.,
	      file descriptors produced by epoll_create(2),  eventfd(2),  ino‐
	      tify_init(2),  signalfd(2), and timerfd(2)), the entry will be a
	      symbolic link with contents of the form

		  anon_inode:<file-type>

	      In some cases, the file-type is surrounded by square brackets.

	      For example, an epoll file descriptor will have a symbolic  link
	      whose content is the string anon_inode:[eventpoll].

	      In  a  multithreaded process, the contents of this directory are
	      not available if the main thread has already  terminated	(typi‐
	      cally by calling pthread_exit(3)).

	      Programs	that  will take a filename as a command-line argument,
	      but will not take input from standard input if  no  argument  is
	      supplied,	 or that write to a file named as a command-line argu‐
	      ment, but will not send their output to standard	output	if  no
	      argument	is  supplied, can nevertheless be made to use standard
	      input or standard out using /proc/[pid]/fd.  For example, assum‐
	      ing  that -i is the flag designating an input file and -o is the
	      flag designating an output file:

		  $ foobar -i /proc/self/fd/0 -o /proc/self/fd/1 ...

	      and you have a working filter.

	      /proc/self/fd/N is approximately the same as /dev/fd/N  in  some
	      UNIX and UNIX-like systems.  Most Linux MAKEDEV scripts symboli‐
	      cally link /dev/fd to /proc/self/fd, in fact.

	      Most systems provide symbolic links /dev/stdin, /dev/stdout, and
	      /dev/stderr, which respectively link to the files 0, 1, and 2 in
	      /proc/self/fd.  Thus the example command above could be  written
	      as:

		  $ foobar -i /dev/stdin -o /dev/stdout ...

       /proc/[pid]/fdinfo/ (since kernel 2.6.22)
	      This  is a subdirectory containing one entry for each file which
	      the process has open, named by its file  descriptor.   The  con‐
	      tents  of	 each file can be read to obtain information about the
	      corresponding file descriptor, for example:

		  $ cat /proc/12015/fdinfo/4
		  pos:	  1000
		  flags:  01002002

	      The pos field is a decimal number showing the current file  off‐
	      set.   The flags field is an octal number that displays the file
	      access mode and file status flags (see open(2)).

	      The files in this directory are readable only by	the  owner  of
	      the process.

       /proc/[pid]/io (since kernel 2.6.20)
	      This file contains I/O statistics for the process, for example:

		  # cat /proc/3828/io
		  rchar: 323934931
		  wchar: 323929600
		  syscr: 632687
		  syscw: 632675
		  read_bytes: 0
		  write_bytes: 323932160
		  cancelled_write_bytes: 0

	      The fields are as follows:

	      rchar: characters read
		     The number of bytes which this task has caused to be read
		     from storage.  This is simply the sum of bytes which this
		     process  passed  to read(2) and similar system calls.  It
		     includes things such as terminal I/O and is unaffected by
		     whether or not actual physical disk I/O was required (the
		     read might have been satisfied from pagecache).

	      wchar: characters written
		     The number of bytes which this task has caused, or	 shall
		     cause  to be written to disk.  Similar caveats apply here
		     as with rchar.

	      syscr: read syscalls
		     Attempt to count the number of read  I/O  operations—that
		     is, system calls such as read(2) and pread(2).

	      syscw: write syscalls
		     Attempt  to count the number of write I/O operations—that
		     is, system calls such as write(2) and pwrite(2).

	      read_bytes: bytes read
		     Attempt to count the number of bytes which	 this  process
		     really  did  cause	 to be fetched from the storage layer.
		     This is accurate for block-backed filesystems.

	      write_bytes: bytes written
		     Attempt to count the number of bytes which	 this  process
		     caused to be sent to the storage layer.

	      cancelled_write_bytes:
		     The big inaccuracy here is truncate.  If a process writes
		     1MB to a file and then deletes the file, it will in  fact
		     perform  no writeout.  But it will have been accounted as
		     having caused 1MB of write.  In other words:  this	 field
		     represents	 the number of bytes which this process caused
		     to not happen, by truncating pagecache.  A task can cause
		     "negative"	 I/O  too.   If this task truncates some dirty
		     pagecache, some I/O which another task has been accounted
		     for (in its write_bytes) will not be happening.

	      Note:  In	 the  current implementation, things are a bit racy on
	      32-bit systems: if process A reads  process  B's	/proc/[pid]/io
	      while  process  B	 is  updating  one  of	these 64-bit counters,
	      process A could see an intermediate result.

       /proc/[pid]/limits (since kernel 2.6.24)
	      This file displays the soft limit, hard limit, and units of mea‐
	      surement	for  each  of the process's resource limits (see getr‐
	      limit(2)).  Up to and including Linux 2.6.35, this file is  pro‐
	      tected  to  allow	 reading  only by the real UID of the process.
	      Since Linux 2.6.36, this file is readable by all	users  on  the
	      system.

       /proc/[pid]/map_files/ (since kernel 3.3)
	      This  subdirectory  contains  entries  corresponding  to memory-
	      mapped files (see mmap(2)).  Entries are named by memory	region
	      start  and  end address pair (expressed as hexadecimal numbers),
	      and are symbolic links to the mapped files themselves.  Here  is
	      an example, with the output wrapped and reformatted to fit on an
	      80-column display:

		  $ ls -l /proc/self/map_files/
		  lr--------. 1 root root 64 Apr 16 21:31
			      3252e00000-3252e20000 -> /usr/lib64/ld-2.15.so
		  ...

	      Although these entries are present for memory regions that  were
	      mapped  with  the MAP_FILE flag, the way anonymous shared memory
	      (regions created with the MAP_ANON | MAP_SHARED flags) is imple‐
	      mented  in  Linux	 means	that  such regions also appear on this
	      directory.  Here is an example where  the	 target	 file  is  the
	      deleted /dev/zero one:

		  lrw-------. 1 root root 64 Apr 16 21:33
			      7fc075d2f000-7fc075e6f000 -> /dev/zero (deleted)

	      This  directory  appears	only  if the CONFIG_CHECKPOINT_RESTORE
	      kernel configuration option is enabled.

       /proc/[pid]/maps
	      A file containing the currently mapped memory regions and	 their
	      access  permissions.   See  mmap(2) for some further information
	      about memory mappings.

	      The format of the file is:

       address		 perms offset  dev   inode	 pathname
       00400000-00452000 r-xp 00000000 08:02 173521	 /usr/bin/dbus-daemon
       00651000-00652000 r--p 00051000 08:02 173521	 /usr/bin/dbus-daemon
       00652000-00655000 rw-p 00052000 08:02 173521	 /usr/bin/dbus-daemon
       00e03000-00e24000 rw-p 00000000 00:00 0		 [heap]
       00e24000-011f7000 rw-p 00000000 00:00 0		 [heap]
       ...
       35b1800000-35b1820000 r-xp 00000000 08:02 135522	 /usr/lib64/ld-2.15.so
       35b1a1f000-35b1a20000 r--p 0001f000 08:02 135522	 /usr/lib64/ld-2.15.so
       35b1a20000-35b1a21000 rw-p 00020000 08:02 135522	 /usr/lib64/ld-2.15.so
       35b1a21000-35b1a22000 rw-p 00000000 00:00 0
       35b1c00000-35b1dac000 r-xp 00000000 08:02 135870	 /usr/lib64/libc-2.15.so
       35b1dac000-35b1fac000 ---p 001ac000 08:02 135870	 /usr/lib64/libc-2.15.so
       35b1fac000-35b1fb0000 r--p 001ac000 08:02 135870	 /usr/lib64/libc-2.15.so
       35b1fb0000-35b1fb2000 rw-p 001b0000 08:02 135870	 /usr/lib64/libc-2.15.so
       ...
       f2c6ff8c000-7f2c7078c000 rw-p 00000000 00:00 0	 [stack:986]
       ...
       7fffb2c0d000-7fffb2c2e000 rw-p 00000000 00:00 0	 [stack]
       7fffb2d48000-7fffb2d49000 r-xp 00000000 00:00 0	 [vdso]

	      The address field is the address space in the process  that  the
	      mapping occupies.	 The perms field is a set of permissions:

		   r = read
		   w = write
		   x = execute
		   s = shared
		   p = private (copy on write)

	      The  offset  field  is the offset into the file/whatever; dev is
	      the device (major:minor); inode is the inode on that device.   0
	      indicates that no inode is associated with the memory region, as
	      would be the case with BSS (uninitialized data).

	      The pathname field will usually be the file that is backing  the
	      mapping.	For ELF files, you can easily coordinate with the off‐
	      set field by looking at the Offset  field	 in  the  ELF  program
	      headers (readelf -l).

	      There are additional helpful pseudo-paths:

		   [stack]
			  The  initial	process's  (also  known	 as  the  main
			  thread's) stack.

		   [stack:<tid>] (since Linux 3.4)
			  A thread's stack (where the <tid> is a  thread  ID).
			  It corresponds to the /proc/[pid]/task/[tid]/ path.

		   [vdso] The virtual dynamically linked shared object.

		   [heap] The process's heap.

	      If  the pathname field is blank, this is an anonymous mapping as
	      obtained via the mmap(2) function.  There	 is  no	 easy  way  to
	      coordinate  this back to a process's source, short of running it
	      through gdb(1), strace(1), or similar.

	      Under Linux 2.0 there is no field giving pathname.

       /proc/[pid]/mem
	      This file can be used to access the pages of a process's	memory
	      through open(2), read(2), and lseek(2).

       /proc/[pid]/mountinfo (since Linux 2.6.26)
	      This  file contains information about mount points.  It contains
	      lines of the form:

	      36 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue
	      (1)(2)(3)	  (4)	(5)	 (6)	  (7)	(8) (9)	  (10)	       (11)

	      The numbers in  parentheses  are	labels	for  the  descriptions
	      below:

	      (1)  mount  ID:  unique  identifier  of the mount (may be reused
		   after umount(2)).

	      (2)  parent ID: ID of parent mount (or of self for  the  top  of
		   the mount tree).

	      (3)  major:minor:	 value	of st_dev for files on filesystem (see
		   stat(2)).

	      (4)  root: root of the mount within the filesystem.

	      (5)  mount point: mount point relative to the process's root.

	      (6)  mount options: per-mount options.

	      (7)  optional  fields:  zero  or	more  fields   of   the	  form
		   "tag[:value]".

	      (8)  separator: marks the end of the optional fields.

	      (9)  filesystem type: name of filesystem in the form "type[.sub‐
		   type]".

	      (10) mount source: filesystem-specific information or "none".

	      (11) super options: per-superblock options.

	      Parsers should ignore all unrecognized  optional	fields.	  Cur‐
	      rently the possible optional fields are:

		   shared:X	     mount is shared in peer group X

		   master:X	     mount is slave to peer group X

		   propagate_from:X  mount  is	slave and receives propagation
				     from peer group X (*)

		   unbindable	     mount is unbindable

	      (*) X is the closest dominant peer  group	 under	the  process's
	      root.  If X is the immediate master of the mount, or if there is
	      no dominant peer group under the same root, then only the	 "mas‐
	      ter:X" field is present and not the "propagate_from:X" field.

	      For  more	 information  on  mount	 propagation  see:  Documenta‐
	      tion/filesystems/sharedsubtree.txt in the	 Linux	kernel	source
	      tree.

       /proc/[pid]/mounts (since Linux 2.4.19)
	      This  is	a list of all the filesystems currently mounted in the
	      process's mount namespace.  The format of	 this  file  is	 docu‐
	      mented  in  fstab(5).  Since kernel version 2.6.15, this file is
	      pollable: after opening the file for reading, a change  in  this
	      file  (i.e.,  a filesystem mount or unmount) causes select(2) to
	      mark  the	 file  descriptor  as  readable,   and	 poll(2)   and
	      epoll_wait(2) mark the file as having an error condition.

       /proc/[pid]/mountstats (since Linux 2.6.17)
	      This  file exports information (statistics, configuration infor‐
	      mation) about the mount points  in  the  process's  name	space.
	      Lines in this file have the form:

	      device /dev/sda7 mounted on /home with fstype ext3 [statistics]
	      (	      1	     )		  ( 2 )		    (3 ) (4)

	      The fields in each line are:

	      (1)  The	name  of the mounted device (or "nodevice" if there is
		   no corresponding device).

	      (2)  The mount point within the filesystem tree.

	      (3)  The filesystem type.

	      (4)  Optional statistics and  configuration  information.	  Cur‐
		   rently  (as	at  Linux 2.6.26), only NFS filesystems export
		   information via this field.

	      This file is readable only by the owner of the process.

       /proc/[pid]/ns/ (since Linux 3.0)
	      This is a subdirectory containing one entry for  each  namespace
	      that  supports  being  manipulated by setns(2).  For information
	      about namespaces, see clone(2).

       /proc/[pid]/ns/ipc (since Linux 3.0)
	      Bind mounting this file (see mount(2)) to somewhere else in  the
	      filesystem  keeps	 the IPC namespace of the process specified by
	      pid alive even if all processes currently in the namespace  ter‐
	      minate.

	      Opening this file returns a file handle for the IPC namespace of
	      the process specified by pid.  As long as this  file  descriptor
	      remains  open,  the IPC namespace will remain alive, even if all
	      processes in the namespace terminate.  The file  descriptor  can
	      be passed to setns(2).

       /proc/[pid]/ns/net (since Linux 3.0)
	      Bind  mounting this file (see mount(2)) to somewhere else in the
	      filesystem keeps the network namespace of the process  specified
	      by pid alive even if all processes in the namespace terminate.

	      Opening  this  file returns a file handle for the network names‐
	      pace of the process specified by pid.   As  long	as  this  file
	      descriptor  remains  open,  the  network	namespace  will remain
	      alive, even if all processes in the  namespace  terminate.   The
	      file descriptor can be passed to setns(2).

       /proc/[pid]/ns/uts (since Linux 3.0)
	      Bind  mounting this file (see mount(2)) to somewhere else in the
	      filesystem keeps the UTS namespace of the process	 specified  by
	      pid  alive even if all processes currently in the namespace ter‐
	      minate.

	      Opening this file returns a file handle for the UTS namespace of
	      the  process  specified by pid.  As long as this file descriptor
	      remains open, the UTS namespace will remain alive, even  if  all
	      processes	 in  the namespace terminate.  The file descriptor can
	      be passed to setns(2).

       /proc/[pid]/numa_maps (since Linux 2.6.14)
	      See numa(7).

       /proc/[pid]/oom_adj (since Linux 2.6.11)
	      This file can be used to adjust the score used to	 select	 which
	      process  should  be  killed in an out-of-memory (OOM) situation.
	      The kernel uses this value for  a	 bit-shift  operation  of  the
	      process's	 oom_score value: valid values are in the range -16 to
	      +15, plus the special  value  -17,  which	 disables  OOM-killing
	      altogether  for  this  process.	A positive score increases the
	      likelihood of this process being killed  by  the	OOM-killer;  a
	      negative score decreases the likelihood.

	      The default value for this file is 0; a new process inherits its
	      parent's	oom_adj	 setting.   A  process	must   be   privileged
	      (CAP_SYS_RESOURCE) to update this file.

	      Since  Linux  2.6.36, use of this file is deprecated in favor of
	      /proc/[pid]/oom_score_adj.

       /proc/[pid]/oom_score (since Linux 2.6.11)
	      This file displays the current score that the  kernel  gives  to
	      this process for the purpose of selecting a process for the OOM-
	      killer.  A higher score means that the process is more likely to
	      be  selected by the OOM-killer.  The basis for this score is the
	      amount of memory used by the  process,  with  increases  (+)  or
	      decreases (-) for factors including:

	      * whether	 the  process  creates a lot of children using fork(2)
		(+);

	      * whether the process has been running a long time, or has  used
		a lot of CPU time (-);

	      * whether the process has a low nice value (i.e., > 0) (+);

	      * whether the process is privileged (-); and

	      * whether the process is making direct hardware access (-).

	      The  oom_score  also  reflects  the  adjustment specified by the
	      oom_score_adj or oom_adj setting for the process.

       /proc/[pid]/oom_score_adj (since Linux 2.6.36)
	      This file can be used to adjust the badness  heuristic  used  to
	      select which process gets killed in out-of-memory conditions.

	      The  badness  heuristic  assigns	a value to each candidate task
	      ranging from 0 (never kill) to 1000 (always kill)	 to  determine
	      which  process  is targeted.  The units are roughly a proportion
	      along that range of allowed  memory  the	process	 may  allocate
	      from, based on an estimation of its current memory and swap use.
	      For example, if a task is using all allowed memory, its  badness
	      score  will be 1000.  If it is using half of its allowed memory,
	      its score will be 500.

	      There is an additional factor included  in  the  badness	score:
	      root processes are given 3% extra memory over other tasks.

	      The  amount  of "allowed" memory depends on the context in which
	      the OOM-killer was called.  If it is due to the memory  assigned
	      to  the  allocating  task's  cpuset being exhausted, the allowed
	      memory represents the set of mems assigned to that  cpuset  (see
	      cpuset(7)).   If	it  is	due  to	 a  mempolicy's	 node(s) being
	      exhausted, the allowed memory represents the  set	 of  mempolicy
	      nodes.   If  it  is  due to a memory limit (or swap limit) being
	      reached, the allowed memory is that configured limit.   Finally,
	      if  it  is  due  to  the	entire system being out of memory, the
	      allowed memory represents all allocatable resources.

	      The value of oom_score_adj is added to the badness score	before
	      it  is  used to determine which task to kill.  Acceptable values
	      range    from	-1000	  (OOM_SCORE_ADJ_MIN)	  to	 +1000
	      (OOM_SCORE_ADJ_MAX).   This  allows  user	 space	to control the
	      preference for OOM-killing, ranging  from	 always	 preferring  a
	      certain  task  or completely disabling it from OOM-killing.  The
	      lowest possible value, -1000, is equivalent  to  disabling  OOM-
	      killing  entirely	 for  that task, since it will always report a
	      badness score of 0.

	      Consequently, it is very simple for user	space  to  define  the
	      amount   of  memory  to  consider	 for  each  task.   Setting  a
	      oom_score_adj value of +500, for example, is roughly  equivalent
	      to  allowing  the	 remainder  of	tasks sharing the same system,
	      cpuset, mempolicy, or memory  controller	resources  to  use  at
	      least  50%  more	memory.	  A  value of -500, on the other hand,
	      would be roughly equivalent to discounting  50%  of  the	task's
	      allowed  memory  from  being  considered	as scoring against the
	      task.

	      For    backward	 compatibility	  with	  previous    kernels,
	      /proc/[pid]/oom_adj can still be used to tune the badness score.
	      Its value is scaled linearly with oom_score_adj.

	      Writing to /proc/[pid]/oom_score_adj or /proc/[pid]/oom_adj will
	      change the other with its scaled value.

       /proc/[pid]/root
	      UNIX  and	 Linux	support	 the idea of a per-process root of the
	      filesystem, set by the chroot(2) system call.  This  file	 is  a
	      symbolic	link  that points to the process's root directory, and
	      behaves in the same way as exe, and fd/*.

	      In a multithreaded process, the contents of this	symbolic  link
	      are  not	available  if  the  main thread has already terminated
	      (typically by calling pthread_exit(3)).

       /proc/[pid]/smaps (since Linux 2.6.14)
	      This file shows memory consumption for  each  of	the  process's
	      mappings.	  For each of mappings there is a series of lines such
	      as the following:

		  08048000-080bc000 r-xp 00000000 03:02 13130	   /bin/bash
		  Size:		      464 kB
		  Rss:		      424 kB
		  Shared_Clean:	      424 kB
		  Shared_Dirty:		0 kB
		  Private_Clean:	0 kB
		  Private_Dirty:	0 kB

	      The first of these lines shows the same information as  is  dis‐
	      played for the mapping in /proc/[pid]/maps.  The remaining lines
	      show the size of the mapping, the amount of the mapping that  is
	      currently	 resident in RAM, the number of clean and dirty shared
	      pages in the mapping, and the number of clean and dirty  private
	      pages in the mapping.

	      This file is present only if the CONFIG_MMU kernel configuration
	      option is enabled.

       /proc/[pid]/stat
	      Status information about the process.  This is  used  by	ps(1).
	      It is defined in /usr/src/linux/fs/proc/array.c.

	      The  fields,  in order, with their proper scanf(3) format speci‐
	      fiers, are:

	      pid %d	  (1) The process ID.

	      comm %s	  (2) The filename of the executable, in  parentheses.
			  This	is  visible  whether  or not the executable is
			  swapped out.

	      state %c	  (3) One character from the string "RSDZTW"  where  R
			  is  running, S is sleeping in an interruptible wait,
			  D is waiting in uninterruptible  disk	 sleep,	 Z  is
			  zombie,  T is traced or stopped (on a signal), and W
			  is paging.

	      ppid %d	  (4) The PID of the parent.

	      pgrp %d	  (5) The process group ID of the process.

	      session %d  (6) The session ID of the process.

	      tty_nr %d	  (7) The controlling terminal of the  process.	  (The
			  minor	 device number is contained in the combination
			  of bits 31 to 20 and 7 to 0; the major device number
			  is in bits 15 to 8.)

	      tpgid %d	  (8)  The  ID	of the foreground process group of the
			  controlling terminal of the process.

	      flags %u (%lu before Linux 2.6.22)
			  (9) The kernel flags word of the process.   For  bit
			  meanings,  see  the PF_* defines in the Linux kernel
			  source file include/linux/sched.h.   Details	depend
			  on the kernel version.

	      minflt %lu  (10) The number of minor faults the process has made
			  which have not required loading a memory  page  from
			  disk.

	      cminflt %lu (11)	The  number of minor faults that the process's
			  waited-for children have made.

	      majflt %lu  (12) The number of major faults the process has made
			  which have required loading a memory page from disk.

	      cmajflt %lu (13)	The  number of major faults that the process's
			  waited-for children have made.

	      utime %lu	  (14) Amount of  time	that  this  process  has  been
			  scheduled  in	 user  mode,  measured	in clock ticks
			  (divide  by  sysconf(_SC_CLK_TCK)).	This  includes
			  guest time, guest_time (time spent running a virtual
			  CPU, see below), so that applications that  are  not
			  aware	 of the guest time field do not lose that time
			  from their calculations.

	      stime %lu	  (15) Amount of  time	that  this  process  has  been
			  scheduled  in	 kernel	 mode, measured in clock ticks
			  (divide by sysconf(_SC_CLK_TCK)).

	      cutime %ld  (16) Amount of time that this	 process's  waited-for
			  children  have been scheduled in user mode, measured
			  in clock  ticks  (divide  by	sysconf(_SC_CLK_TCK)).
			  (See	also  times(2).)   This	 includes  guest time,
			  cguest_time (time spent running a virtual  CPU,  see
			  below).

	      cstime %ld  (17)	Amount	of time that this process's waited-for
			  children have been scheduled in  kernel  mode,  mea‐
			  sured	     in	    clock     ticks	(divide	    by
			  sysconf(_SC_CLK_TCK)).

	      priority %ld
			  (18) (Explanation for Linux 2.6) For processes  run‐
			  ning	a  real-time  scheduling policy (policy below;
			  see  sched_setscheduler(2)),	this  is  the  negated
			  scheduling priority, minus one; that is, a number in
			  the range -2 to  -100,  corresponding	 to  real-time
			  priorities  1	 to 99.	 For processes running under a
			  non-real-time scheduling policy,  this  is  the  raw
			  nice	value  (setpriority(2))	 as represented in the
			  kernel.  The kernel stores nice values as numbers in
			  the range 0 (high) to 39 (low), corresponding to the
			  user-visible nice range of -20 to 19.

			  Before Linux 2.6, this was a scaled value  based  on
			  the scheduler weighting given to this process.

	      nice %ld	  (19) The nice value (see setpriority(2)), a value in
			  the range 19 (low priority) to -20 (high priority).

	      num_threads %ld
			  (20) Number of threads in this process (since	 Linux
			  2.6).	  Before kernel 2.6, this field was hard coded
			  to 0 as a placeholder for an earlier removed field.

	      itrealvalue %ld
			  (21) The time in jiffies before the next SIGALRM  is
			  sent to the process due to an interval timer.	 Since
			  kernel 2.6.17, this field is no  longer  maintained,
			  and is hard coded as 0.

	      starttime %llu (was %lu before Linux 2.6)
			  (22) The time the process started after system boot.
			  In  kernels  before  Linux  2.6,  this   value   was
			  expressed in jiffies.	 Since Linux 2.6, the value is
			  expressed    in    clock    ticks	(divide	    by
			  sysconf(_SC_CLK_TCK)).

	      vsize %lu	  (23) Virtual memory size in bytes.

	      rss %ld	  (24)	Resident Set Size: number of pages the process
			  has in real memory.  This is just  the  pages	 which
			  count	 toward text, data, or stack space.  This does
			  not include pages which have not been	 demand-loaded
			  in, or which are swapped out.

	      rsslim %lu  (25)	Current	 soft limit in bytes on the rss of the
			  process; see the description of RLIMIT_RSS in	 getr‐
			  limit(2).

	      startcode %lu
			  (26) The address above which program text can run.

	      endcode %lu (27) The address below which program text can run.

	      startstack %lu
			  (28)	The address of the start (i.e., bottom) of the
			  stack.

	      kstkesp %lu (29) The current value of ESP	 (stack	 pointer),  as
			  found in the kernel stack page for the process.

	      kstkeip %lu (30) The current EIP (instruction pointer).

	      signal %lu  (31)	The  bitmap of pending signals, displayed as a
			  decimal number.  Obsolete, because it does not  pro‐
			  vide	 information   on   real-time	signals;   use
			  /proc/[pid]/status instead.

	      blocked %lu (32) The bitmap of blocked signals, displayed	 as  a
			  decimal  number.  Obsolete, because it does not pro‐
			  vide	 information   on   real-time	signals;   use
			  /proc/[pid]/status instead.

	      sigignore %lu
			  (33)	The  bitmap of ignored signals, displayed as a
			  decimal number.  Obsolete, because it does not  pro‐
			  vide	 information   on   real-time	signals;   use
			  /proc/[pid]/status instead.

	      sigcatch %lu
			  (34) The bitmap of caught signals,  displayed	 as  a
			  decimal  number.  Obsolete, because it does not pro‐
			  vide	 information   on   real-time	signals;   use
			  /proc/[pid]/status instead.

	      wchan %lu	  (35)	This  is the "channel" in which the process is
			  waiting.  It is the address of  a  location  in  the
			  kernel  where	 the  process is sleeping.  The corre‐
			  sponding   symbolic	name   can   be	   found    in
			  /proc/[pid]/wchan.

	      nswap %lu	  (36) Number of pages swapped (not maintained).

	      cnswap %lu  (37) Cumulative nswap for child processes (not main‐
			  tained).

	      exit_signal %d (since Linux 2.1.22)
			  (38) Signal to be sent to parent when we die.

	      processor %d (since Linux 2.2.8)
			  (39) CPU number last executed on.

	      rt_priority %u (since Linux 2.5.19; was %lu before Linux 2.6.22)
			  (40) Real-time scheduling priority, a number in  the
			  range	 1 to 99 for processes scheduled under a real-
			  time policy, or 0, for non-real-time processes  (see
			  sched_setscheduler(2)).

	      policy %u (since Linux 2.5.19; was %lu before Linux 2.6.22)
			  (41)	Scheduling policy (see sched_setscheduler(2)).
			  Decode using the SCHED_* constants in linux/sched.h.

	      delayacct_blkio_ticks %llu (since Linux 2.6.18)
			  (42) Aggregated block I/O delays, measured in	 clock
			  ticks (centiseconds).

	      guest_time %lu (since Linux 2.6.24)
			  (43) Guest time of the process (time spent running a
			  virtual CPU for a guest operating system),  measured
			  in clock ticks (divide by sysconf(_SC_CLK_TCK)).

	      cguest_time %ld (since Linux 2.6.24)
			  (44)	Guest time of the process's children, measured
			  in clock ticks (divide by sysconf(_SC_CLK_TCK)).

       /proc/[pid]/statm
	      Provides information about memory usage, measured in pages.  The
	      columns are:

		  size	     (1) total program size
			     (same as VmSize in /proc/[pid]/status)
		  resident   (2) resident set size
			     (same as VmRSS in /proc/[pid]/status)
		  share	     (3) shared pages (i.e., backed by a file)
		  text	     (4) text (code)
		  lib	     (5) library (unused in Linux 2.6)
		  data	     (6) data + stack
		  dt	     (7) dirty pages (unused in Linux 2.6)

       /proc/[pid]/status
	      Provides	 much  of  the	information  in	 /proc/[pid]/stat  and
	      /proc/[pid]/statm in a format that's easier for humans to parse.
	      Here's an example:

		  $ cat /proc/$$/status
		  Name:	  bash
		  State:  S (sleeping)
		  Tgid:	  3515
		  Pid:	  3515
		  PPid:	  3452
		  TracerPid:	  0
		  Uid:	  1000	  1000	  1000	  1000
		  Gid:	  100	  100	  100	  100
		  FDSize: 256
		  Groups: 16 33 100
		  VmPeak:     9136 kB
		  VmSize:     7896 kB
		  VmLck:	 0 kB
		  VmHWM:      7572 kB
		  VmRSS:      6316 kB
		  VmData:     5224 kB
		  VmStk:	88 kB
		  VmExe:       572 kB
		  VmLib:      1708 kB
		  VmPTE:	20 kB
		  Threads:	  1
		  SigQ:	  0/3067
		  SigPnd: 0000000000000000
		  ShdPnd: 0000000000000000
		  SigBlk: 0000000000010000
		  SigIgn: 0000000000384004
		  SigCgt: 000000004b813efb
		  CapInh: 0000000000000000
		  CapPrm: 0000000000000000
		  CapEff: 0000000000000000
		  CapBnd: ffffffffffffffff
		  Cpus_allowed:	  00000001
		  Cpus_allowed_list:	  0
		  Mems_allowed:	  1
		  Mems_allowed_list:	  0
		  voluntary_ctxt_switches:	  150
		  nonvoluntary_ctxt_switches:	  545

	      The fields are as follows:

	      * Name: Command run by this process.

	      * State: Current state of the process.  One of "R (running)", "S
		(sleeping)", "D (disk  sleep)",	 "T  (stopped)",  "T  (tracing
		stop)", "Z (zombie)", or "X (dead)".

	      * Tgid: Thread group ID (i.e., Process ID).

	      * Pid: Thread ID (see gettid(2)).

	      * PPid: PID of parent process.

	      * TracerPid: PID of process tracing this process (0 if not being
		traced).

	      * Uid, Gid: Real, effective,  saved  set,	 and  filesystem  UIDs
		(GIDs).

	      * FDSize: Number of file descriptor slots currently allocated.

	      * Groups: Supplementary group list.

	      * VmPeak: Peak virtual memory size.

	      * VmSize: Virtual memory size.

	      * VmLck: Locked memory size (see mlock(3)).

	      * VmHWM: Peak resident set size ("high water mark").

	      * VmRSS: Resident set size.

	      * VmData, VmStk, VmExe: Size of data, stack, and text segments.

	      * VmLib: Shared library code size.

	      * VmPTE: Page table entries size (since Linux 2.6.10).

	      * Threads: Number of threads in process containing this thread.

	      * SigQ:  This  field  contains  two slash-separated numbers that
		relate to queued signals for the real user ID of this process.
		The  first  of these is the number of currently queued signals
		for this real user ID, and the second is the resource limit on
		the  number  of	 queued	 signals  for  this  process  (see the
		description of RLIMIT_SIGPENDING in getrlimit(2)).

	      * SigPnd, ShdPnd: Number of signals pending for thread  and  for
		process as a whole (see pthreads(7) and signal(7)).

	      * SigBlk,	  SigIgn,   SigCgt:  Masks  indicating	signals	 being
		blocked, ignored, and caught (see signal(7)).

	      * CapInh, CapPrm,	 CapEff:  Masks	 of  capabilities  enabled  in
		inheritable,  permitted,  and  effective  sets	(see capabili‐
		ties(7)).

	      * CapBnd: Capability Bounding  set  (since  kernel  2.6.26,  see
		capabilities(7)).

	      * Cpus_allowed:  Mask  of	 CPUs  on  which  this process may run
		(since Linux 2.6.24, see cpuset(7)).

	      * Cpus_allowed_list: Same as  previous,  but  in	"list  format"
		(since Linux 2.6.26, see cpuset(7)).

	      * Mems_allowed:  Mask  of	 memory	 nodes allowed to this process
		(since Linux 2.6.24, see cpuset(7)).

	      * Mems_allowed_list: Same as  previous,  but  in	"list  format"
		(since Linux 2.6.26, see cpuset(7)).

	      * voluntary_context_switches,	nonvoluntary_context_switches:
		Number of voluntary and involuntary  context  switches	(since
		Linux 2.6.23).

       /proc/[pid]/task (since Linux 2.6.0-test6)
	      This  is	a  directory  that  contains one subdirectory for each
	      thread in the process.  The name of  each	 subdirectory  is  the
	      numerical	 thread	 ID  ([tid])  of  the  thread (see gettid(2)).
	      Within each of these subdirectories, there is  a	set  of	 files
	      with the same names and contents as under the /proc/[pid] direc‐
	      tories.  For attributes that are shared by all threads, the con‐
	      tents  for each of the files under the task/[tid] subdirectories
	      will be the same as in the  corresponding	 file  in  the	parent
	      /proc/[pid]  directory (e.g., in a multithreaded process, all of
	      the task/[tid]/cwd  files	 will  have  the  same	value  as  the
	      /proc/[pid]/cwd  file  in the parent directory, since all of the
	      threads in a process share a working directory).	For attributes
	      that are distinct for each thread, the corresponding files under
	      task/[tid] may have different values (e.g.,  various  fields  in
	      each  of	the  task/[tid]/status files may be different for each
	      thread).

	      In a multithreaded process, the contents of the /proc/[pid]/task
	      directory	 are not available if the main thread has already ter‐
	      minated (typically by calling pthread_exit(3)).

       /proc/[pid]/wchan (since Linux 2.6.0)
	      The symbolic name corresponding to the location  in  the	kernel
	      where the process is sleeping.

       /proc/apm
	      Advanced	power  management version and battery information when
	      CONFIG_APM is defined at kernel compilation time.

       /proc/bus
	      Contains subdirectories for installed busses.

       /proc/bus/pccard
	      Subdirectory for PCMCIA devices when  CONFIG_PCMCIA  is  set  at
	      kernel compilation time.

       /proc/[pid]/timers (since Linux 3.10)
	      A	 list  of  the	POSIX  timers for this process.	 Each timer is
	      listed with a line that started  with  the  string  "ID:".   For
	      example:

		  ID: 1
		  signal: 60/00007fff86e452a8
		  notify: signal/pid.2634
		  ClockID: 0
		  ID: 0
		  signal: 60/00007fff86e452a8
		  notify: signal/pid.2634
		  ClockID: 1

	      The lines shown for each timer have the following meanings:

	      ID     The ID for this timer.  This is not the same as the timer
		     ID returned by timer_create(2); rather, it	 is  the  same
		     kernel-internal  ID  that is available via the si_timerid
		     field of the siginfo_t structure (see sigaction(2)).

	      signal This is the signal number that this timer uses to deliver
		     notifications   followed	by   a	slash,	and  then  the
		     sigev_value.sival_ptr value supplied to the  signal  han‐
		     dler.  Valid only for timers that notify via a signal.

	      notify The  part	before	the slash specifies the mechanism that
		     this timer uses to deliver notifications, and is  one  of
		     "thread", "signal", or "none".  Immediately following the
		     slash  is	either	the  string  "tid"  for	 timers	  with
		     SIGEV_THREAD_ID  notification,  or	 "pid" for timers that
		     notify by other mechanisms.  Following the "." is the PID
		     of	 the  process  that  will be delivered a signal if the
		     timer delivers notifications via a signal.

	      ClockID
		     This field identifies the clock that the timer  uses  for
		     measuring	time.	For most clocks, this is a number that
		     matches one of the user-space CLOCK_*  constants  exposed
		     via  <time.h>.   CLOCK_PROCESS_CPUTIME_ID	timers display
		     with    a	  value	   of	 -6	in     this	field.
		     CLOCK_THREAD_CPUTIME_ID timers display with a value of -2
		     in this field.

       /proc/bus/pccard/drivers

       /proc/bus/pci
	      Contains various bus subdirectories and pseudo-files  containing
	      information  about  PCI  busses,	installed  devices, and device
	      drivers.	Some of these files are not ASCII.

       /proc/bus/pci/devices
	      Information about PCI devices.  They  may	 be  accessed  through
	      lspci(8) and setpci(8).

       /proc/cmdline
	      Arguments	 passed	 to the Linux kernel at boot time.  Often done
	      via a boot manager such as lilo(8) or grub(8).

       /proc/config.gz (since Linux 2.6)
	      This file exposes the configuration options that	were  used  to
	      build  the  currently running kernel, in the same format as they
	      would be shown in the .config file that resulted when  configur‐
	      ing  the	kernel	(using make xconfig, make config, or similar).
	      The file contents are compressed;	 view  or  search  them	 using
	      zcat(1)  and  zgrep(1).  As long as no changes have been made to
	      the following file, the contents of /proc/config.gz are the same
	      as those provided by :

		  cat /lib/modules/$(uname -r)/build/.config

	      /proc/config.gz  is  provided  only  if the kernel is configured
	      with CONFIG_IKCONFIG_PROC.

       /proc/cpuinfo
	      This is a collection of CPU and  system  architecture  dependent
	      items,  for  each	 supported architecture a different list.  Two
	      common  entries  are  processor  which  gives  CPU  number   and
	      bogomips;	 a  system  constant  that is calculated during kernel
	      initialization.  SMP machines have  information  for  each  CPU.
	      The lscpu(1) command gathers its information from this file.

       /proc/devices
	      Text  listing  of	 major numbers and device groups.  This can be
	      used by MAKEDEV scripts for consistency with the kernel.

       /proc/diskstats (since Linux 2.5.69)
	      This file contains disk I/O statistics  for  each	 disk  device.
	      See  the	Linux kernel source file Documentation/iostats.txt for
	      further information.

       /proc/dma
	      This is a list of the registered ISA DMA (direct memory  access)
	      channels in use.

       /proc/driver
	      Empty subdirectory.

       /proc/execdomains
	      List of the execution domains (ABI personalities).

       /proc/fb
	      Frame buffer information when CONFIG_FB is defined during kernel
	      compilation.

       /proc/filesystems
	      A text listing of the filesystems which  are  supported  by  the
	      kernel,  namely  filesystems which were compiled into the kernel
	      or  whose	 kernel	 modules  are  currently  loaded.   (See  also
	      filesystems(5).)	 If  a filesystem is marked with "nodev", this
	      means that it does not require a	block  device  to  be  mounted
	      (e.g., virtual filesystem, network filesystem).

	      Incidentally, this file may be used by mount(8) when no filesys‐
	      tem is specified and it didn't manage to determine the  filesys‐
	      tem  type.   Then	 filesystems  contained in this file are tried
	      (excepted those that are marked with "nodev").

       /proc/fs
	      Empty subdirectory.

       /proc/ide
	      This directory exists on systems with the IDE  bus.   There  are
	      directories  for	each  IDE  channel and attached device.	 Files
	      include:

		  cache		     buffer size in KB
		  capacity	     number of sectors
		  driver	     driver version
		  geometry	     physical and logical geometry
		  identify	     in hexadecimal
		  media		     media type
		  model		     manufacturer's model number
		  settings	     drive settings
		  smart_thresholds   in hexadecimal
		  smart_values	     in hexadecimal

	      The hdparm(8) utility provides access to this information	 in  a
	      friendly format.

       /proc/interrupts
	      This  is	used to record the number of interrupts per CPU per IO
	      device.  Since Linux 2.6.24, for the i386 and  x86_64  architec‐
	      tures,  at  least, this also includes interrupts internal to the
	      system (that is, not associated with a device as such), such  as
	      NMI  (nonmaskable	 interrupt),  LOC (local timer interrupt), and
	      for SMP systems, TLB (TLB flush  interrupt),  RES	 (rescheduling
	      interrupt),  CAL	(remote function call interrupt), and possibly
	      others.  Very easy to read formatting, done in ASCII.

       /proc/iomem
	      I/O memory map in Linux 2.4.

       /proc/ioports
	      This is a list of currently registered Input-Output port regions
	      that are in use.

       /proc/kallsyms (since Linux 2.5.71)
	      This  holds  the	kernel exported symbol definitions used by the
	      modules(X) tools to dynamically link and bind loadable  modules.
	      In  Linux	 2.5.47 and earlier, a similar file with slightly dif‐
	      ferent syntax was named ksyms.

       /proc/kcore
	      This file represents the physical memory of the  system  and  is
	      stored  in the ELF core file format.  With this pseudo-file, and
	      an unstripped kernel (/usr/src/linux/vmlinux) binary, GDB can be
	      used to examine the current state of any kernel data structures.

	      The  total  length  of  the  file is the size of physical memory
	      (RAM) plus 4KB.

       /proc/kmsg
	      This file can be used instead of the syslog(2)  system  call  to
	      read  kernel messages.  A process must have superuser privileges
	      to read this file, and only one process should read  this	 file.
	      This  file  should  not  be  read if a syslog process is running
	      which uses the syslog(2) system call facility to log kernel mes‐
	      sages.

	      Information in this file is retrieved with the dmesg(1) program.

       /proc/ksyms (Linux 1.1.23-2.5.47)
	      See /proc/kallsyms.

       /proc/loadavg
	      The  first  three	 fields	 in this file are load average figures
	      giving the number of jobs in the run queue (state R) or  waiting
	      for disk I/O (state D) averaged over 1, 5, and 15 minutes.  They
	      are the same as the load average numbers given by uptime(1)  and
	      other  programs.	The fourth field consists of two numbers sepa‐
	      rated by a slash (/).  The first of these is the number of  cur‐
	      rently runnable kernel scheduling entities (processes, threads).
	      The value after the slash is the	number	of  kernel  scheduling
	      entities that currently exist on the system.  The fifth field is
	      the PID of the process that was most  recently  created  on  the
	      system.

       /proc/locks
	      This  file  shows current file locks (flock(2) and fcntl(2)) and
	      leases (fcntl(2)).

       /proc/malloc (only up to and including Linux 2.2)
	      This file is present only	 if  CONFIG_DEBUG_MALLOC  was  defined
	      during compilation.

       /proc/meminfo
	      This  file  reports statistics about memory usage on the system.
	      It is used by free(1) to report the amount of free and used mem‐
	      ory (both physical and swap) on the system as well as the shared
	      memory and buffers used by the kernel.  Each line	 of  the  file
	      consists	of a parameter name, followed by a colon, the value of
	      the parameter, and an option unit of measurement	(e.g.,	"kB").
	      The  list	 below	describes  the	parameter names and the format
	      specifier required to read the field  value.   Except  as	 noted
	      below,  all of the fields have been present since at least Linux
	      2.6.0.  Some fileds are displayed only if the kernel was config‐
	      ured  with  various options; those dependencies are noted in the
	      list.

	      MemTotal %lu
		     Total usable RAM (i.e., physical RAM minus a few reserved
		     bits and the kernel binary code).

	      MemFree %lu
		     The sum of LowFree+HighFree.

	      Buffers %lu
		     Relatively	 temporary  storage  for  raw disk blocks that
		     shouldn't get tremendously large (20MB or so).

	      Cached %lu
		     In-memory cache for files read from the  disk  (the  page
		     cache).  Doesn't include SwapCached.

	      SwapCached %lu
		     Memory  that once was swapped out, is swapped back in but
		     still also is in the swap file.  (If memory  pressure  is
		     high,  these  pages  don't	 need  to be swapped out again
		     because they are already in the swap  file.   This	 saves
		     I/O.)

	      Active %lu
		     Memory  that  has been used more recently and usually not
		     reclaimed unless absolutely necessary.

	      Inactive %lu
		     Memory which has been less recently  used.	  It  is  more
		     eligible to be reclaimed for other purposes.

	      Active(anon) %lu (since Linux 2.6.28)
		     [To be documented.]

	      Inactive(anon) %lu (since Linux 2.6.28)
		     [To be documented.]

	      Active(file) %lu (since Linux 2.6.28)
		     [To be documented.]

	      Inactive(file) %lu (since Linux 2.6.28)
		     [To be documented.]

	      Unevictable %lu (since Linux 2.6.28)
		     (From  Linux 2.6.28 to 2.6.30, CONFIG_UNEVICTABLE_LRU was
		     required.)	 [To be documented.]

	      Mlocked %lu (since Linux 2.6.28)
		     (From Linux 2.6.28 to 2.6.30, CONFIG_UNEVICTABLE_LRU  was
		     required.)	 [To be documented.]

	      HighTotal %lu
		     (Starting with Linux 2.6.19, CONFIG_HIGHMEM is required.)
		     Total amount of highmem.  Highmem	is  all	 memory	 above
		     ~860MB  of physical memory.  Highmem areas are for use by
		     user-space programs, or for the page cache.   The	kernel
		     must  use	tricks to access this memory, making it slower
		     to access than lowmem.

	      HighFree %lu
		     (Starting with Linux 2.6.19, CONFIG_HIGHMEM is required.)
		     Amount of free highmem.

	      LowTotal %lu
		     (Starting with Linux 2.6.19, CONFIG_HIGHMEM is required.)
		     Total amount of lowmem.  Lowmem is memory	which  can  be
		     used  for everything that highmem can be used for, but it
		     is also available for the kernel's use for its  own  data
		     structures.   Among many other things, it is where every‐
		     thing from Slab is allocated.   Bad  things  happen  when
		     you're out of lowmem.

	      LowFree %lu
		     (Starting with Linux 2.6.19, CONFIG_HIGHMEM is required.)
		     Amount of free lowmem.

	      MmapCopy %lu (since Linux 2.6.29)
		     (CONFIG_MMU is required.)	[To be documented.]

	      SwapTotal %lu
		     Total amount of swap space available.

	      SwapFree %lu
		     Amount of swap space that is currently unused.

	      Dirty %lu
		     Memory which is waiting to get written back to the disk.

	      Writeback %lu
		     Memory which is actively being written back to the disk.

	      AnonPages %lu (since Linux 2.6.18)
		     Non-file backed pages mapped into user-space page tables.

	      Mapped %lu
		     Files which have been mmaped, such as libraries.

	      Shmem %lu (since Linux 2.6.32)
		     [To be documented.]

	      Slab %lu
		     In-kernel data structures cache.

	      SReclaimable %lu (since Linux 2.6.19)
		     Part of Slab, that might be reclaimed, such as caches.

	      SUnreclaim %lu (since Linux 2.6.19)
		     Part of Slab, that cannot be reclaimed  on	 memory	 pres‐
		     sure.

	      KernelStack %lu (since Linux 2.6.32)
		     Amount of memory allocated to kernel stacks.

	      PageTables %lu (since Linux 2.6.18)
		     Amount  of	 memory	 dedicated to the lowest level of page
		     tables.

	      Quicklists %lu (since Linux 2.6.27)
		     (CONFIG_QUICKLIST is required.)  [To be documented.]

	      NFS_Unstable %lu (since Linux 2.6.18)
		     NFS pages sent to the server, but not  yet	 committed  to
		     stable storage.

	      Bounce %lu (since Linux 2.6.18)
		     Memory used for block device "bounce buffers".

	      WritebackTmp %lu (since Linux 2.6.26)
		     Memory used by FUSE for temporary writeback buffers.

	      CommitLimit %lu (since Linux 2.6.10)
		     Based  on	the  overcommit ratio ('vm.overcommit_ratio'),
		     this is the total amount of  memory  currently  available
		     to	 be allocated on the system.  This limit is adhered to
		     only if strict overcommit accounting is enabled  (mode  2
		     in	 /proc/sys/vm/overcommit_ratio).   The	CommitLimit is
		     calculated using the following formula:

			 CommitLimit =
			     ([total RAM pages] - [total huge TLB pages]) *
			     overcommit_ratio / 100 + [total swap pages]

		     For example, on a system with 1GB of physical RAM and 7GB
		     of	 swap  with  a	overcommit_ratio  of  30, this formula
		     yields a CommitLimit of 7.3GB.  For more details, see the
		     memory overcommit documentation in the kernel source file
		     Documentation/vm/overcommit-accounting.

	      Committed_AS %lu
		     The amount of memory presently allocated on  the  system.
		     The  committed memory is a sum of all of the memory which
		     has been allocated by processes, even if it has not  been
		     "used"  by them as of yet.	 A process which allocates 1GB
		     of memory (using malloc(3) or similar), but touches  only
		     300MB  of that memory will show up as using only 300MB of
		     memory even if it has the address space allocated for the
		     entire  1GB.   This 1GB is memory which has been "commit‐
		     ted" to by the VM and can be used	at  any	 time  by  the
		     allocating	 application.	With strict overcommit enabled
		     on the system  (mode  2  /proc/sys/vm/overcommit_memory),
		     allocations  which would exceed the CommitLimit (detailed
		     above) will not be permitted.   This  is  useful  if  one
		     needs  to	guarantee  that processes will not fail due to
		     lack of memory once that  memory  has  been  successfully
		     allocated.

	      VmallocTotal %lu
		     Total size of vmalloc memory area.

	      VmallocUsed %lu
		     Amount of vmalloc area which is used.

	      VmallocChunk %lu
		     Largest contiguous block of vmalloc area which is free.

	      HardwareCorrupted %lu (since Linux 2.6.32)
		     (CONFIG_MEMORY_FAILURE is required.)  [To be documented.]

	      AnonHugePages %lu (since Linux 2.6.38)
		     (CONFIG_TRANSPARENT_HUGEPAGE   is	 required.)   Non-file
		     backed huge pages mapped into user-space page tables.

	      HugePages_Total %lu
		     (CONFIG_HUGETLB_PAGE is required.)	 The size of the  pool
		     of huge pages.

	      HugePages_Free %lu
		     (CONFIG_HUGETLB_PAGE  is  required.)   The number of huge
		     pages in the pool that are not yet allocated.

	      HugePages_Rsvd %lu (since Linux 2.6.17)
		     (CONFIG_HUGETLB_PAGE is required.)	 This is the number of
		     huge  pages  for  which a commitment to allocate from the
		     pool has been made, but no allocation has yet been	 made.
		     These  reserved  huge pages guarantee that an application
		     will be able to allocate a huge page  from	 the  pool  of
		     huge pages at fault time.

	      HugePages_Surp %lu (since Linux 2.6.24)
		     (CONFIG_HUGETLB_PAGE is required.)	 This is the number of
		     huge   pages   in	 the   pool   above   the   value   in
		     /proc/sys/vm/nr_hugepages.	 The maximum number of surplus
		     huge  pages  is  controlled  by  /proc/sys/vm/nr_overcom‐
		     mit_hugepages.

	      Hugepagesize %lu
		     (CONFIG_HUGETLB_PAGE  is  required.)   The	 size  of huge
		     pages.

       /proc/modules
	      A text list of the modules that have been loaded by the  system.
	      See also lsmod(8).

       /proc/mounts
	      Before  kernel  2.4.19, this file was a list of all the filesys‐
	      tems currently mounted on the system.  With the introduction  of
	      per-process mount namespaces in Linux 2.4.19, this file became a
	      link to /proc/self/mounts, which lists the mount points  of  the
	      process's own mount namespace.  The format of this file is docu‐
	      mented in fstab(5).

       /proc/mtrr
	      Memory Type Range Registers.  See the Linux kernel  source  file
	      Documentation/mtrr.txt for details.

       /proc/net
	      various  net  pseudo-files, all of which give the status of some
	      part of the networking layer.  These files contain ASCII	struc‐
	      tures  and  are,	therefore, readable with cat(1).  However, the
	      standard netstat(8) suite provides much cleaner access to	 these
	      files.

       /proc/net/arp
	      This  holds  an ASCII readable dump of the kernel ARP table used
	      for address resolutions.	It will show both dynamically  learned
	      and preprogrammed ARP entries.  The format is:

	IP address     HW type	 Flags	   HW address	       Mask   Device
	192.168.0.50   0x1	 0x2	   00:50:BF:25:68:F3   *      eth0
	192.168.0.250  0x1	 0xc	   00:00:00:00:00:00   *      eth0

	      Here "IP address" is the IPv4 address of the machine and the "HW
	      type" is the hardware type of the	 address  from	RFC 826.   The
	      flags are the internal flags of the ARP structure (as defined in
	      /usr/include/linux/if_arp.h) and the "HW address"	 is  the  data
	      link layer mapping for that IP address if it is known.

       /proc/net/dev
	      The  dev pseudo-file contains network device status information.
	      This gives the number of received and sent packets,  the	number
	      of  errors and collisions and other basic statistics.  These are
	      used by the ifconfig(8) program to report	 device	 status.   The
	      format is:

 Inter-|   Receive						  |  Transmit
  face |bytes	 packets errs drop fifo frame compressed multicast|bytes    packets errs drop fifo colls carrier compressed
     lo: 2776770   11307    0	 0    0	    0	       0	 0  2776770   11307    0    0	 0     0       0	  0
   eth0: 1215645    2751    0	 0    0	    0	       0	 0  1782404    4324    0    0	 0   427       0	  0
   ppp0: 1622270    5552    1	 0    0	    0	       0	 0   354130    5669    0    0	 0     0       0	  0
   tap0:    7714      81    0	 0    0	    0	       0	 0     7714	 81    0    0	 0     0       0	  0

       /proc/net/dev_mcast
	      Defined in /usr/src/linux/net/core/dev_mcast.c:
		   indx interface_name	dmi_u dmi_g dmi_address
		   2	eth0		1     0	    01005e000001
		   3	eth1		1     0	    01005e000001
		   4	eth2		1     0	    01005e000001

       /proc/net/igmp
	      Internet	   Group     Management	   Protocol.	 Defined    in
	      /usr/src/linux/net/core/igmp.c.

       /proc/net/rarp
	      This file uses the same format as the arp file and contains  the
	      current reverse mapping database used to provide rarp(8) reverse
	      address lookup services.	If RARP is  not	 configured  into  the
	      kernel, this file will not be present.

       /proc/net/raw
	      Holds  a	dump of the RAW socket table.  Much of the information
	      is not of use apart from debugging.  The "sl" value is the  ker‐
	      nel  hash	 slot for the socket, the "local_address" is the local
	      address and protocol number pair.	 "St" is the  internal	status
	      of  the  socket.	The "tx_queue" and "rx_queue" are the outgoing
	      and incoming data queue in terms of kernel  memory  usage.   The
	      "tr", "tm->when", and "rexmits" fields are not used by RAW.  The
	      "uid" field holds the  effective	UID  of	 the  creator  of  the
	      socket.

       /proc/net/snmp
	      This file holds the ASCII data needed for the IP, ICMP, TCP, and
	      UDP management information bases for an SNMP agent.

       /proc/net/tcp
	      Holds a dump of the TCP socket table.  Much of  the  information
	      is  not of use apart from debugging.  The "sl" value is the ker‐
	      nel hash slot for the socket, the "local_address" is  the	 local
	      address  and  port number pair.  The "rem_address" is the remote
	      address and port number pair (if connected).  "St" is the inter‐
	      nal status of the socket.	 The "tx_queue" and "rx_queue" are the
	      outgoing and incoming data  queue	 in  terms  of	kernel	memory
	      usage.  The "tr", "tm->when", and "rexmits" fields hold internal
	      information of the kernel socket state and are only  useful  for
	      debugging.   The "uid" field holds the effective UID of the cre‐
	      ator of the socket.

       /proc/net/udp
	      Holds a dump of the UDP socket table.  Much of  the  information
	      is  not of use apart from debugging.  The "sl" value is the ker‐
	      nel hash slot for the socket, the "local_address" is  the	 local
	      address  and  port number pair.  The "rem_address" is the remote
	      address and port number pair (if connected). "St" is the	inter‐
	      nal status of the socket.	 The "tx_queue" and "rx_queue" are the
	      outgoing and incoming data  queue	 in  terms  of	kernel	memory
	      usage.   The "tr", "tm->when", and "rexmits" fields are not used
	      by UDP.  The "uid" field holds the effective UID of the  creator
	      of the socket.  The format is:

 sl  local_address rem_address	 st tx_queue rx_queue tr rexmits  tm->when uid
  1: 01642C89:0201 0C642C89:03FF 01 00000000:00000001 01:000071BA 00000000 0
  1: 00000000:0801 00000000:0000 0A 00000000:00000000 00:00000000 6F000100 0
  1: 00000000:0201 00000000:0000 0A 00000000:00000000 00:00000000 00000000 0

       /proc/net/unix
	      Lists  the  UNIX	domain	sockets	 present within the system and
	      their status.  The format is:
	      Num RefCount Protocol Flags    Type St Path
	       0: 00000002 00000000 00000000 0001 03
	       1: 00000001 00000000 00010000 0001 01 /dev/printer

	      Here "Num" is the kernel table slot number,  "RefCount"  is  the
	      number of users of the socket, "Protocol" is currently always 0,
	      "Flags" represent the internal kernel flags holding  the	status
	      of the socket.  Currently, type is always "1" (UNIX domain data‐
	      gram sockets are not yet supported in the kernel).  "St" is  the
	      internal state of the socket and Path is the bound path (if any)
	      of the socket.

       /proc/partitions
	      Contains the major and minor numbers of each partition  as  well
	      as the number of 1024-byte blocks and the partition name.

       /proc/pci
	      This  is	a  listing of all PCI devices found during kernel ini‐
	      tialization and their configuration.

	      This file has been deprecated in favor of a new /proc  interface
	      for  PCI	(/proc/bus/pci).   It  became  optional	 in  Linux 2.2
	      (available with CONFIG_PCI_OLD_PROC set at kernel	 compilation).
	      It  became  once more nonoptionally enabled in Linux 2.4.	 Next,
	      it was deprecated	 in  Linux  2.6	 (still	 available  with  CON‐
	      FIG_PCI_LEGACY_PROC  set),  and finally removed altogether since
	      Linux 2.6.17.

       /proc/profile (since Linux 2.4)
	      This file is present only if the kernel was booted with the pro‐
	      file=1  command-line option.  It exposes kernel profiling infor‐
	      mation in a binary format for use	 by  readprofile(1).   Writing
	      (e.g.,  an empty string) to this file resets the profiling coun‐
	      ters; on some architectures, writing a binary integer "profiling
	      multiplier"  of  size  sizeof(int)  sets the profiling interrupt
	      frequency.

       /proc/scsi
	      A directory with the scsi mid-level pseudo-file and various SCSI
	      low-level driver directories, which contain a file for each SCSI
	      host in this system, all of which give the status of  some  part
	      of  the SCSI IO subsystem.  These files contain ASCII structures
	      and are, therefore, readable with cat(1).

	      You can also write to some of the files to reconfigure the  sub‐
	      system or switch certain features on or off.

       /proc/scsi/scsi
	      This  is a listing of all SCSI devices known to the kernel.  The
	      listing is similar to the one seen  during  bootup.   scsi  cur‐
	      rently  supports only the add-single-device command which allows
	      root to add a hotplugged device to the list of known devices.

	      The command

		  echo 'scsi add-single-device 1 0 5 0' > /proc/scsi/scsi

	      will cause host scsi1 to scan on SCSI channel 0 for a device  on
	      ID  5 LUN 0.  If there is already a device known on this address
	      or the address is invalid, an error will be returned.

       /proc/scsi/[drivername]
	      [drivername]  can	 currently  be	NCR53c7xx,  aha152x,  aha1542,
	      aha1740, aic7xxx, buslogic, eata_dma, eata_pio, fdomain, in2000,
	      pas16, qlogic, scsi_debug, seagate, t128,	 u15-24f,  ultrastore,
	      or  wd7000.  These directories show up for all drivers that reg‐
	      istered at least one SCSI HBA.   Every  directory	 contains  one
	      file  per	 registered  host.  Every host-file is named after the
	      number the host was assigned during initialization.

	      Reading these files will usually show driver and host configura‐
	      tion, statistics, and so on.

	      Writing  to  these  files	 allows	 different things on different
	      hosts.  For example, with the latency  and  nolatency  commands,
	      root  can	 switch on and off command latency measurement code in
	      the eata_dma driver.  With the lockup and unlock commands,  root
	      can control bus lockups simulated by the scsi_debug driver.

       /proc/self
	      This  directory  refers  to  the	process	 accessing  the	 /proc
	      filesystem, and is identical to the /proc directory named by the
	      process ID of the same process.

       /proc/slabinfo
	      Information  about  kernel caches.  Since Linux 2.6.16 this file
	      is present only if the CONFIG_SLAB kernel	 configuration	option
	      is enabled.  The columns in /proc/slabinfo are:

		  cache-name
		  num-active-objs
		  total-objs
		  object-size
		  num-active-slabs
		  total-slabs
		  num-pages-per-slab

	      See slabinfo(5) for details.

       /proc/stat
	      kernel/system  statistics.   Varies  with	 architecture.	Common
	      entries include:

	      cpu  3357 0 4313 1362393
		     The  amount  of  time,  measured  in  units  of   USER_HZ
		     (1/100ths	 of   a	 second	 on  most  architectures,  use
		     sysconf(_SC_CLK_TCK) to obtain the right value), that the
		     system spent in various states:

		     user   (1) Time spent in user mode.

		     nice   (2)	 Time  spent  in  user	mode with low priority
			    (nice).

		     system (3) Time spent in system mode.

		     idle   (4) Time spent  in	the  idle  task.   This	 value
			    should  be	USER_HZ	 times the second entry in the
			    /proc/uptime pseudo-file.

		     iowait (since Linux 2.5.41)
			    (5) Time waiting for I/O to complete.

		     irq (since Linux 2.6.0-test4)
			    (6) Time servicing interrupts.

		     softirq (since Linux 2.6.0-test4)
			    (7) Time servicing softirqs.

		     steal (since Linux 2.6.11)
			    (8) Stolen time, which is the time spent in	 other
			    operating  systems	when  running in a virtualized
			    environment

		     guest (since Linux 2.6.24)
			    (9) Time spent running a  virtual  CPU  for	 guest
			    operating  systems	under the control of the Linux
			    kernel.

		     guest_nice (since Linux 2.6.33)
			    (10) Time spent running a niced guest (virtual CPU
			    for	 guest	operating systems under the control of
			    the Linux kernel).

	      page 5741 1808
		     The number of pages the system paged in  and  the	number
		     that were paged out (from disk).

	      swap 1 0
		     The  number  of  swap pages that have been brought in and
		     out.

	      intr 1462898
		     This line shows counts of interrupts serviced since  boot
		     time,  for	 each  of the possible system interrupts.  The
		     first column is the total	of  all	 interrupts  serviced;
		     each  subsequent  column  is  the	total for a particular
		     interrupt.

	      disk_io: (2,0):(31,30,5764,1,2) (3,0):...
		     (major,disk_idx):(noinfo,	   read_io_ops,	    blks_read,
		     write_io_ops, blks_written)
		     (Linux 2.4 only)

	      ctxt 115315
		     The number of context switches that the system underwent.

	      btime 769041601
		     boot   time,  in  seconds	since  the  Epoch,  1970-01-01
		     00:00:00 +0000 (UTC).

	      processes 86031
		     Number of forks since boot.

	      procs_running 6
		     Number of processes in  runnable  state.	(Linux	2.5.45
		     onward.)

	      procs_blocked 2
		     Number  of processes blocked waiting for I/O to complete.
		     (Linux 2.5.45 onward.)

       /proc/swaps
	      Swap areas in use.  See also swapon(8).

       /proc/sys
	      This directory (present since 1.3.57) contains a number of files
	      and  subdirectories  corresponding  to  kernel variables.	 These
	      variables can be read and sometimes  modified  using  the	 /proc
	      filesystem, and the (deprecated) sysctl(2) system call.

       /proc/sys/abi (since Linux 2.4.10)
	      This  directory may contain files with application binary infor‐
	      mation.	See  the   Linux   kernel   source   file   Documenta‐
	      tion/sysctl/abi.txt for more information.

       /proc/sys/debug
	      This directory may be empty.

       /proc/sys/dev
	      This   directory	contains  device-specific  information	(e.g.,
	      dev/cdrom/info).	On some systems, it may be empty.

       /proc/sys/fs
	      This directory contains the files and subdirectories for	kernel
	      variables related to filesystems.

       /proc/sys/fs/binfmt_misc
	      Documentation  for  files	 in this directory can be found in the
	      Linux kernel sources in Documentation/binfmt_misc.txt.

       /proc/sys/fs/dentry-state (since Linux 2.2)
	      This file contains information about the status of the directory
	      cache  (dcache).	 The  file  contains  six  numbers, nr_dentry,
	      nr_unused,  age_limit  (age  in  seconds),   want_pages	(pages
	      requested by system) and two dummy values.

	      * nr_dentry   is	 the  number  of  allocated  dentries  (dcache
		entries).  This field is unused in Linux 2.2.

	      * nr_unused is the number of unused dentries.

	      * age_limit is the age in seconds after which dcache entries can
		be reclaimed when memory is short.

	      * want_pages   is	  nonzero   when   the	 kernel	  has	called
		shrink_dcache_pages() and the dcache isn't pruned yet.

       /proc/sys/fs/dir-notify-enable
	      This file can be used to disable or enable the dnotify interface
	      described	 in  fcntl(2) on a system-wide basis.  A value of 0 in
	      this file disables the interface, and a value of 1 enables it.

       /proc/sys/fs/dquot-max
	      This file shows the maximum number of cached disk quota entries.
	      On some (2.4) systems, it is not present.	 If the number of free
	      cached disk quota entries is very low and you have some  awesome
	      number of simultaneous system users, you might want to raise the
	      limit.

       /proc/sys/fs/dquot-nr
	      This file shows the number of allocated disk quota  entries  and
	      the number of free disk quota entries.

       /proc/sys/fs/epoll (since Linux 2.6.28)
	      This  directory contains the file max_user_watches, which can be
	      used to limit the amount of kernel memory consumed by the	 epoll
	      interface.  For further details, see epoll(7).

       /proc/sys/fs/file-max
	      This  file  defines  a  system-wide  limit on the number of open
	      files for all processes.	(See also setrlimit(2), which  can  be
	      used  by	a process to set the per-process limit, RLIMIT_NOFILE,
	      on the number of files it may open.)  If you get lots  of	 error
	      messages	in  the	 kernel	 log about running out of file handles
	      (look for "VFS: file-max limit <number> reached"), try  increas‐
	      ing this value:

		  echo 100000 > /proc/sys/fs/file-max

	      The  kernel constant NR_OPEN imposes an upper limit on the value
	      that may be placed in file-max.

	      Privileged processes (CAP_SYS_ADMIN) can override	 the  file-max
	      limit.

       /proc/sys/fs/file-nr
	      This  (read-only)	 file  contains	 three	numbers: the number of
	      allocated file handles (i.e.,  the  number  of  files  presently
	      opened); the number of free file handles; and the maximum number
	      of file handles (i.e., the same value as /proc/sys/fs/file-max).
	      If the number of allocated file handles is close to the maximum,
	      you should consider increasing the maximum.  Before  Linux  2.6,
	      the  kernel  allocated  file  handles dynamically, but it didn't
	      free them again.	Instead the free file handles were kept	 in  a
	      list  for	 reallocation; the "free file handles" value indicates
	      the size of that list.  A large  number  of  free	 file  handles
	      indicates	 that  there was a past peak in the usage of open file
	      handles.	Since Linux 2.6, the kernel does deallocate freed file
	      handles, and the "free file handles" value is always zero.

       /proc/sys/fs/inode-max (only present until Linux 2.2)
	      This file contains the maximum number of in-memory inodes.  This
	      value should be 3-4 times larger than  the  value	 in  file-max,
	      since  stdin,  stdout  and network sockets also need an inode to
	      handle them.  When you regularly run out of inodes, you need  to
	      increase this value.

	      Starting	with  Linux  2.4, there is no longer a static limit on
	      the number of inodes, and this file is removed.

       /proc/sys/fs/inode-nr
	      This file contains the first two values from inode-state.

       /proc/sys/fs/inode-state
	      This file contains  seven	 numbers:  nr_inodes,  nr_free_inodes,
	      preshrink, and four dummy values (always zero).

	      nr_inodes	 is  the  number  of  inodes the system has allocated.
	      nr_free_inodes represents the number of free inodes.

	      preshrink is nonzero when the nr_inodes > inode-max and the sys‐
	      tem  needs  to  prune the inode list instead of allocating more;
	      since Linux 2.4, this field is a dummy value (always zero).

       /proc/sys/fs/inotify (since Linux 2.6.13)
	      This     directory     contains	  files	    max_queued_events,
	      max_user_instances,  and	max_user_watches,  that can be used to
	      limit the amount of kernel memory consumed by the inotify inter‐
	      face.  For further details, see inotify(7).

       /proc/sys/fs/lease-break-time
	      This file specifies the grace period that the kernel grants to a
	      process holding a file lease (fcntl(2)) after it has sent a sig‐
	      nal to that process notifying it that another process is waiting
	      to open the file.	 If the lease holder does not remove or	 down‐
	      grade  the  lease	 within this grace period, the kernel forcibly
	      breaks the lease.

       /proc/sys/fs/leases-enable
	      This  file  can  be  used	 to  enable  or	 disable  file	leases
	      (fcntl(2))  on  a	 system-wide basis.  If this file contains the
	      value 0, leases are disabled.  A nonzero value enables leases.

       /proc/sys/fs/mqueue (since Linux 2.6.6)
	      This  directory  contains	 files	 msg_max,   msgsize_max,   and
	      queues_max,  controlling	the  resources	used  by POSIX message
	      queues.  See mq_overview(7) for details.

       /proc/sys/fs/overflowgid and /proc/sys/fs/overflowuid
	      These files allow you to change the value of the fixed  UID  and
	      GID.   The  default  is  65534.	Some  filesystems support only
	      16-bit UIDs and GIDs, although in Linux UIDs  and	 GIDs  are  32
	      bits.   When  one	 of  these  filesystems is mounted with writes
	      enabled, any UID or GID that would exceed 65535 is translated to
	      the overflow value before being written to disk.

       /proc/sys/fs/pipe-max-size (since Linux 2.6.35)
	      The  value  in  this file defines an upper limit for raising the
	      capacity of a pipe using the  fcntl(2)  F_SETPIPE_SZ  operation.
	      This  limit applies only to unprivileged processes.  The default
	      value for this file is 1,048,576.	 The value  assigned  to  this
	      file  may	 be  rounded  upward,  to  reflect  the value actually
	      employed for a  convenient  implementation.   To	determine  the
	      rounded-up  value,  display  the	contents  of  this  file after
	      assigning a value to it.	The minimum value that can be assigned
	      to this file is the system page size.

       /proc/sys/fs/protected_hardlinks (since Linux 3.6)
	      When  the value in this file is 0, no restrictions are placed on
	      the creation of hard links (i.e., this is the historical	behav‐
	      iour  before  Linux  3.6).   When the value in this file is 1, a
	      hard link can be created to a target file only  if  one  of  the
	      following conditions is true:

	      *	 The caller has the CAP_FOWNER capability.

	      *	 The  filesystem  UID of the process creating the link matches
		 the owner (UID) of the target file (as described  in  creden‐
		 tials(7),  a process's filesystem UID is normally the same as
		 its effective UID).

	      *	 All of the following conditions are true:

		  ·  the target is a regular file;

		  ·  the target file does not have its set-user-ID  permission
		     bit enabled;

		  ·  the  target  file does not have both its set-group-ID and
		     group-executable permission bits enabled; and

		  ·  the caller has permission to read and  write  the	target
		     file  (either  via the file's permissions mask or because
		     it has suitable capabilities).

	      The default value in this file is 0.  Setting  the  value	 to  1
	      prevents a longstanding class of security issues caused by hard-
	      link-based time-of-check, time-of-use races, most commonly  seen
	      in  world-writable  directories such as /tmp.  The common method
	      of exploiting this flaw is to cross  privilege  boundaries  when
	      following a given hard link (i.e., a root process follows a hard
	      link created by another user).  Additionally, on systems without
	      separated	 partitions,  this stops unauthorized users from "pin‐
	      ning" vulnerable	set-user-ID  and  set-group-ID	files  against
	      being  upgraded  by  the	administrator,	or  linking to special
	      files.

       /proc/sys/fs/protected_symlinks (since Linux 3.6)
	      When the value in this file is 0, no restrictions are placed  on
	      following symbolic links (i.e., this is the historical behaviour
	      before Linux 3.6).  When the value in this file is  1,  symbolic
	      links are followed only in the following circumstances:

	      *	 the  filesystem UID of the process following the link matches
		 the owner (UID) of the symbolic link (as described in creden‐
		 tials(7),  a process's filesystem UID is normally the same as
		 its effective UID);

	      *	 the link is not in a sticky world-writable directory; or

	      *	 the symbolic link and its  parent  directory  have  the  same
		 owner (UID)

	      A	 system	 call  that fails to follow a symbolic link because of
	      the above restrictions returns the error EACCES in errno.

	      The default value in this file is 0.  Setting  the  value	 to  1
	      avoids a longstanding class of security issues based on time-of-
	      check, time-of-use races when accessing symbolic links.

       /proc/sys/fs/suid_dumpable (since Linux 2.6.13)
	      The value in this file determines whether core  dump  files  are
	      produced	for  set-user-ID  or otherwise protected/tainted bina‐
	      ries.  Three different integer values can be specified:

	      0 (default)
		     This provides the traditional (pre-Linux  2.6.13)	behav‐
		     ior.   A  core  dump  will	 not be produced for a process
		     which has changed	credentials  (by  calling  seteuid(2),
		     setgid(2),	 or  similar, or by executing a set-user-ID or
		     set-group-ID program) or whose binary does not have  read
		     permission enabled.

	      1 ("debug")
		     All  processes dump core when possible.  The core dump is
		     owned by the filesystem user ID of	 the  dumping  process
		     and  no security is applied.  This is intended for system
		     debugging situations only.	 Ptrace is unchecked.

	      2 ("suidsafe")
		     Any binary which normally would not be  dumped  (see  "0"
		     above)  is dumped readable by root only.  This allows the
		     user to remove the core dump file but  not	 to  read  it.
		     For  security  reasons  core  dumps in this mode will not
		     overwrite one another  or	other  files.	This  mode  is
		     appropriate  when	administrators are attempting to debug
		     problems in a normal environment.

		     Additionally, since Linux 3.6, /proc/sys/kernel/core_pat‐
		     tern  must	 either be an absolute pathname or a pipe com‐
		     mand, as detailed in core(5).  Warnings will  be  written
		     to	 the  kernel log if core_pattern does not follow these
		     rules, and no core dump will be produced.

       /proc/sys/fs/super-max
	      This file controls the maximum number of superblocks,  and  thus
	      the  maximum  number of mounted filesystems the kernel can have.
	      You need increase only super-max	if  you	 need  to  mount  more
	      filesystems than the current value in super-max allows you to.

       /proc/sys/fs/super-nr
	      This file contains the number of filesystems currently mounted.

       /proc/sys/kernel
	      This  directory  contains	 files	controlling  a range of kernel
	      parameters, as described below.

       /proc/sys/kernel/acct
	      This file contains three numbers: highwater, lowwater, and  fre‐
	      quency.  If BSD-style process accounting is enabled these values
	      control its behavior.  If free space on filesystem where the log
	      lives  goes below lowwater percent accounting suspends.  If free
	      space gets above highwater  percent  accounting  resumes.	  fre‐
	      quency determines how often the kernel checks the amount of free
	      space (value is in seconds).  Default values are 4,  2  and  30.
	      That  is, suspend accounting if 2% or less space is free; resume
	      it if 4% or more	space  is  free;  consider  information	 about
	      amount of free space valid for 30 seconds.

       /proc/sys/kernel/cap_last_cap (since Linux 3.2)
	      See capabilities(7).

       /proc/sys/kernel/cap-bound (from Linux 2.2 to 2.6.24)
	      This  file holds the value of the kernel capability bounding set
	      (expressed as a signed  decimal  number).	  This	set  is	 ANDed
	      against	the   capabilities   permitted	to  a  process	during
	      execve(2).  Starting with Linux 2.6.25, the system-wide capabil‐
	      ity  bounding  set disappeared, and was replaced by a per-thread
	      bounding set; see capabilities(7).

       /proc/sys/kernel/core_pattern
	      See core(5).

       /proc/sys/kernel/core_uses_pid
	      See core(5).

       /proc/sys/kernel/ctrl-alt-del
	      This file controls the handling of Ctrl-Alt-Del  from  the  key‐
	      board.   When  the  value	 in  this  file	 is 0, Ctrl-Alt-Del is
	      trapped and sent to the init(8) program  to  handle  a  graceful
	      restart.	 When the value is greater than zero, Linux's reaction
	      to a Vulcan Nerve Pinch (tm) will be an immediate reboot,	 with‐
	      out  even syncing its dirty buffers.  Note: when a program (like
	      dosemu) has the keyboard in  "raw"  mode,	 the  ctrl-alt-del  is
	      intercepted by the program before it ever reaches the kernel tty
	      layer, and it's up to the program to decide what to do with it.

       /proc/sys/kernel/dmesg_restrict (since Linux 2.6.37)
	      The value in this file determines who can see kernel syslog con‐
	      tents.   A  value of 0 in this file imposes no restrictions.  If
	      the value is 1, only privileged users can read the  kernel  sys‐
	      log.   (See  syslog(2) for more details.)	 Since Linux 3.4, only
	      users with the CAP_SYS_ADMIN capability may change the value  in
	      this file.

       /proc/sys/kernel/domainname and /proc/sys/kernel/hostname
	      can  be  used  to	 set the NIS/YP domainname and the hostname of
	      your box in exactly the same way as the  commands	 domainname(1)
	      and hostname(1), that is:

		  # echo 'darkstar' > /proc/sys/kernel/hostname
		  # echo 'mydomain' > /proc/sys/kernel/domainname

	      has the same effect as

		  # hostname 'darkstar'
		  # domainname 'mydomain'

	      Note,  however, that the classic darkstar.frop.org has the host‐
	      name "darkstar" and DNS (Internet Domain Name Server) domainname
	      "frop.org", not to be confused with the NIS (Network Information
	      Service) or YP (Yellow  Pages)  domainname.   These  two	domain
	      names  are  in general different.	 For a detailed discussion see
	      the hostname(1) man page.

       /proc/sys/kernel/hotplug
	      This file contains the path for the hotplug policy  agent.   The
	      default value in this file is /sbin/hotplug.

       /proc/sys/kernel/htab-reclaim
	      (PowerPC	only) If this file is set to a nonzero value, the Pow‐
	      erPC htab (see kernel  file  Documentation/powerpc/ppc_htab.txt)
	      is pruned each time the system hits the idle loop.

       /proc/sys/kernel/kptr_restrict (since Linux 2.6.38)
	      The  value  in this file determines whether kernel addresses are
	      exposed via /proc files and other interfaces.  A value of	 0  in
	      this  file  imposes  no restrictions.  If the value is 1, kernel
	      pointers printed using the %pK format specifier will be replaced
	      with  zeros  unless  the user has the CAP_SYSLOG capability.  If
	      the value is 2, kernel pointers printed  using  the  %pK	format
	      specifier	 will  be replaced with zeros regardless of the user's
	      capabilities.  The initial default value for this	 file  was  1,
	      but  the	default was changed to 0 in Linux 2.6.39.  Since Linux
	      3.4, only users with the CAP_SYS_ADMIN capability can change the
	      value in this file.

       /proc/sys/kernel/l2cr
	      (PowerPC	only)  This  file contains a flag that controls the L2
	      cache of G3 processor boards.  If	 0,  the  cache	 is  disabled.
	      Enabled if nonzero.

       /proc/sys/kernel/modprobe
	      This  file  contains the path for the kernel module loader.  The
	      default value is /sbin/modprobe.	The file is  present  only  if
	      the  kernel  is  built  with  the CONFIG_MODULES (CONFIG_KMOD in
	      Linux 2.6.26 and earlier) option enabled.	 It  is	 described  by
	      the  Linux  kernel  source  file Documentation/kmod.txt (present
	      only in kernel 2.4 and earlier).

       /proc/sys/kernel/modules_disabled (since Linux 2.6.31)
	      A toggle value indicating if modules are allowed to be loaded in
	      an  otherwise  modular kernel.  This toggle defaults to off (0),
	      but can be set true (1).	Once  true,  modules  can  be  neither
	      loaded nor unloaded, and the toggle cannot be set back to false.
	      The file is present only if the kernel is built  with  the  CON‐
	      FIG_MODULES option enabled.

       /proc/sys/kernel/msgmax
	      This  file  defines  a  system-wide limit specifying the maximum
	      number of bytes in a single message written on a System  V  mes‐
	      sage queue.

       /proc/sys/kernel/msgmni (since Linux 2.4)
	      This file defines the system-wide limit on the number of message
	      queue identifiers.

       /proc/sys/kernel/msgmnb
	      This file defines a system-wide parameter used to initialize the
	      msg_qbytes setting for subsequently created message queues.  The
	      msg_qbytes setting specifies the maximum number  of  bytes  that
	      may be written to the message queue.

       /proc/sys/kernel/ngroups_max (since Linux 2.6.4)
	      This  is	a  read-only file that displays the upper limit on the
	      number of a process's group memberships.

       /proc/sys/kernel/ostype and /proc/sys/kernel/osrelease
	      These files give substrings of /proc/version.

       /proc/sys/kernel/overflowgid and /proc/sys/kernel/overflowuid
	      These files duplicate  the  files	 /proc/sys/fs/overflowgid  and
	      /proc/sys/fs/overflowuid.

       /proc/sys/kernel/panic
	      This  file  gives	 read/write  access  to	 the  kernel  variable
	      panic_timeout.  If this is zero,	the  kernel  will  loop	 on  a
	      panic; if nonzero it indicates that the kernel should autoreboot
	      after this number of seconds.  When you use the software	watch‐
	      dog device driver, the recommended setting is 60.

       /proc/sys/kernel/panic_on_oops (since Linux 2.5.68)
	      This  file controls the kernel's behavior when an oops or BUG is
	      encountered.  If this file contains 0, then the system tries  to
	      continue	operation.  If it contains 1, then the system delays a
	      few seconds (to give klogd time to record the oops  output)  and
	      then panics.  If the /proc/sys/kernel/panic file is also nonzero
	      then the machine will be rebooted.

       /proc/sys/kernel/pid_max (since Linux 2.5.34)
	      This file specifies the value at which PIDs wrap	around	(i.e.,
	      the  value  in  this  file is one greater than the maximum PID).
	      The default value for this file,	32768,	results	 in  the  same
	      range of PIDs as on earlier kernels.  On 32-bit platforms, 32768
	      is the maximum value for pid_max.	 On  64-bit  systems,  pid_max
	      can be set to any value up to 2^22 (PID_MAX_LIMIT, approximately
	      4 million).

       /proc/sys/kernel/powersave-nap (PowerPC only)
	      This file contains a flag.  If set, Linux-PPC will use the "nap"
	      mode of powersaving, otherwise the "doze" mode will be used.

       /proc/sys/kernel/printk
	      The  four values in this file are console_loglevel, default_mes‐
	      sage_loglevel,	minimum_console_level,	  and	  default_con‐
	      sole_loglevel.   These  values  influence printk() behavior when
	      printing or logging error messages.  See syslog(2) for more info
	      on  the  different  loglevels.   Messages with a higher priority
	      than console_loglevel will be printed to the console.   Messages
	      without  an  explicit  priority  will  be	 printed with priority
	      default_message_level.  minimum_console_loglevel is the  minimum
	      (highest)	  value	  to   which   console_loglevel	 can  be  set.
	      default_console_loglevel	is  the	  default   value   for	  con‐
	      sole_loglevel.

       /proc/sys/kernel/pty (since Linux 2.6.4)
	      This directory contains two files relating to the number of UNIX
	      98 pseudoterminals (see pts(4)) on the system.

       /proc/sys/kernel/pty/max
	      This file defines the maximum number of pseudoterminals.

       /proc/sys/kernel/pty/nr
	      This read-only file indicates how many pseudoterminals are  cur‐
	      rently in use.

       /proc/sys/kernel/random
	      This directory contains various parameters controlling the oper‐
	      ation of the file /dev/random.  See random(4) for further infor‐
	      mation.

       /proc/sys/kernel/random/uuid (since Linux 2.4)
	      Each  read from this read-only file returns a randomly generated
	      128-bit UUID, as a string in the standard UUID format.

       /proc/sys/kernel/real-root-dev
	      This file is documented in the Linux kernel source file Documen‐
	      tation/initrd.txt.

       /proc/sys/kernel/reboot-cmd (Sparc only)
	      This  file  seems	 to  be a way to give an argument to the SPARC
	      ROM/Flash boot loader.  Maybe  to	 tell  it  what	 to  do	 after
	      rebooting?

       /proc/sys/kernel/rtsig-max
	      (Only  in	 kernels  up to and including 2.6.7; see setrlimit(2))
	      This file can be used to tune the maximum number of POSIX	 real-
	      time (queued) signals that can be outstanding in the system.

       /proc/sys/kernel/rtsig-nr
	      (Only  in	 kernels  up to and including 2.6.7.)  This file shows
	      the number POSIX real-time signals currently queued.

       /proc/sys/kernel/sched_rr_timeslice_ms (since Linux 3.9)
	      See sched_rr_get_interval(2).

       /proc/sys/kernel/sem (since Linux 2.4)
	      This file contains 4 numbers defining limits for	System	V  IPC
	      semaphores.  These fields are, in order:

	      SEMMSL  The maximum semaphores per semaphore set.

	      SEMMNS  A	 system-wide  limit on the number of semaphores in all
		      semaphore sets.

	      SEMOPM  The maximum number of operations that may	 be  specified
		      in a semop(2) call.

	      SEMMNI  A	 system-wide  limit on the maximum number of semaphore
		      identifiers.

       /proc/sys/kernel/sg-big-buff
	      This file shows the size of the generic SCSI device (sg) buffer.
	      You  can't  tune it just yet, but you could change it at compile
	      time by editing include/scsi/sg.h	 and  changing	the  value  of
	      SG_BIG_BUFF.   However,  there shouldn't be any reason to change
	      this value.

       /proc/sys/kernel/shm_rmid_forced (since Linux 3.1)
	      If this file is set to 1, all System V  shared  memory  segments
	      will be marked for destruction as soon as the number of attached
	      processes falls to zero; in other words, it is no longer	possi‐
	      ble to create shared memory segments that exist independently of
	      any attached process.

	      The effect is as though a shmctl(2) IPC_RMID is performed on all
	      existing	segments as well as all segments created in the future
	      (until this file is reset to 0).	Note  that  existing  segments
	      that  are	 attached  to no process will be immediately destroyed
	      when this file is set to	1.   Setting  this  option  will  also
	      destroy  segments	 that  were  created, but never attached, upon
	      termination  of  the  process  that  created  the	 segment  with
	      shmget(2).

	      Setting  this file to 1 provides a way of ensuring that all Sys‐
	      tem V shared memory segments are counted	against	 the  resource
	      usage  and  resource limits (see the description of RLIMIT_AS in
	      getrlimit(2)) of at least one process.

	      Because setting this file to 1 produces behavior	that  is  non‐
	      standard and could also break existing applications, the default
	      value in this file is 0.	Only set this file to 1 if you have  a
	      good  understanding  of  the semantics of the applications using
	      System V shared memory on your system.

       /proc/sys/kernel/shmall
	      This file contains the system-wide limit on the total number  of
	      pages of System V shared memory.

       /proc/sys/kernel/shmmax
	      This file can be used to query and set the run-time limit on the
	      maximum (System V IPC) shared memory segment size	 that  can  be
	      created.	 Shared memory segments up to 1GB are now supported in
	      the kernel.  This value defaults to SHMMAX.

       /proc/sys/kernel/shmmni (since Linux 2.4)
	      This file specifies the system-wide maximum number of  System  V
	      shared memory segments that can be created.

       /proc/sys/kernel/sysrq
	      This  file  controls  the functions allowed to be invoked by the
	      SysRq key.  By default, the file contains 1 meaning  that	 every
	      possible	SysRq  request	is  allowed (in older kernel versions,
	      SysRq was disabled by default, and you were required to specifi‐
	      cally enable it at run-time, but this is not the case any more).
	      Possible values in this file are:

		 0 - disable sysrq completely
		 1 - enable all functions of sysrq
		>1 - bit mask of allowed sysrq functions, as follows:
			2 - enable control of console logging level
			4 - enable control of keyboard (SAK, unraw)
			8 - enable debugging dumps of processes etc.
		       16 - enable sync command
		       32 - enable remount read-only
		       64 - enable signaling of processes  (term,  kill,  oom-
	      kill)
		      128 - allow reboot/poweroff
		      256 - allow nicing of all real-time tasks

	      This  file is present only if the CONFIG_MAGIC_SYSRQ kernel con‐
	      figuration option is enabled.  For further details see the Linux
	      kernel source file Documentation/sysrq.txt.

       /proc/sys/kernel/version
	      This file contains a string like:

		  #5 Wed Feb 25 21:49:24 MET 1998

	      The  "#5"	 means	that  this is the fifth kernel built from this
	      source base and the date behind it indicates the time the kernel
	      was built.

       /proc/sys/kernel/threads-max (since Linux 2.3.11)
	      This  file  specifies  the  system-wide  limit  on the number of
	      threads (tasks) that can be created on the system.

       /proc/sys/kernel/zero-paged (PowerPC only)
	      This file contains a flag.  When	enabled	 (nonzero),  Linux-PPC
	      will  pre-zero  pages  in	 the  idle  loop, possibly speeding up
	      get_free_pages.

       /proc/sys/net
	      This directory contains networking stuff.	 Explanations for some
	      of  the  files  under  this directory can be found in tcp(7) and
	      ip(7).

       /proc/sys/net/core/somaxconn
	      This file defines a ceiling value for the	 backlog  argument  of
	      listen(2); see the listen(2) manual page for details.

       /proc/sys/proc
	      This directory may be empty.

       /proc/sys/sunrpc
	      This  directory  supports	 Sun remote procedure call for network
	      filesystem (NFS).	 On some systems, it is not present.

       /proc/sys/vm
	      This directory contains files for memory management tuning, buf‐
	      fer and cache management.

       /proc/sys/vm/drop_caches (since Linux 2.6.16)
	      Writing  to  this	 file  causes the kernel to drop clean caches,
	      dentries, and inodes from memory, causing that memory to	become
	      free.  This can be useful for memory management testing and per‐
	      forming reproducible filesystem benchmarks.  Because writing  to
	      this  file  causes  the  benefits	 of caching to be lost, it can
	      degrade overall system performance.

	      To free pagecache, use:

		  echo 1 > /proc/sys/vm/drop_caches

	      To free dentries and inodes, use:

		  echo 2 > /proc/sys/vm/drop_caches

	      To free pagecache, dentries and inodes, use:

		  echo 3 > /proc/sys/vm/drop_caches

	      Because writing to this file is a nondestructive	operation  and
	      dirty  objects  are  not	freeable,  the user should run sync(8)
	      first.

       /proc/sys/vm/legacy_va_layout (since Linux 2.6.9)
	      If nonzero, this disables the new 32-bit memory-mapping  layout;
	      the kernel will use the legacy (2.4) layout for all processes.

       /proc/sys/vm/memory_failure_early_kill (since Linux 2.6.32)
	      Control  how  to kill processes when an uncorrected memory error
	      (typically a 2-bit error in a memory module) that cannot be han‐
	      dled  by	the  kernel is detected in the background by hardware.
	      In some cases (like the page still having a valid copy on disk),
	      the kernel will handle the failure transparently without affect‐
	      ing any applications.  But if there is no other up-to-date  copy
	      of  the data, it will kill processes to prevent any data corrup‐
	      tions from propagating.

	      The file has one of the following values:

	      1:  Kill all processes that have	the  corrupted-and-not-reload‐
		  able	page  mapped  as  soon	as the corruption is detected.
		  Note this is not supported for a few types  of  pages,  like
		  kernel  internally  allocated	 data  or  the swap cache, but
		  works for the majority of user pages.

	      0:  Only unmap the corrupted page from all  processes  and  kill
		  only a process that tries to access it.

	      The  kill is performed using a SIGBUS signal with si_code set to
	      BUS_MCEERR_AO.  Processes can handle this if they want  to;  see
	      sigaction(2) for more details.

	      This  feature  is	 active	 only  on architectures/platforms with
	      advanced machine check handling  and  depends  on	 the  hardware
	      capabilities.

	      Applications  can override the memory_failure_early_kill setting
	      individually with the prctl(2) PR_MCE_KILL operation.

	      Only present if  the  kernel  was	 configured  with  CONFIG_MEM‐
	      ORY_FAILURE.

       /proc/sys/vm/memory_failure_recovery (since Linux 2.6.32)
	      Enable memory failure recovery (when supported by the platform)

	      1:  Attempt recovery.

	      0:  Always panic on a memory failure.

	      Only  present  if	 the  kernel  was  configured with CONFIG_MEM‐
	      ORY_FAILURE.

       /proc/sys/vm/oom_dump_tasks (since Linux 2.6.25)
	      Enables a system-wide task dump (excluding kernel threads) to be
	      produced	when  the  kernel  performs  an OOM-killing.  The dump
	      includes	the  following	information  for  each	task  (thread,
	      process): thread ID, real user ID, thread group ID (process ID),
	      virtual memory size, resident set size, the CPU that the task is
	      scheduled	  on,	oom_adj	  score	  (see	 the   description  of
	      /proc/[pid]/oom_adj), and command	 name.	 This  is  helpful  to
	      determine	 why  the  OOM-killer  was invoked and to identify the
	      rogue task that caused it.

	      If this contains the value zero, this information is suppressed.
	      On  very	large  systems	with thousands of tasks, it may not be
	      feasible to dump the memory  state  information  for  each  one.
	      Such systems should not be forced to incur a performance penalty
	      in OOM situations when the information may not be desired.

	      If this is set to nonzero, this information  is  shown  whenever
	      the OOM-killer actually kills a memory-hogging task.

	      The default value is 0.

       /proc/sys/vm/oom_kill_allocating_task (since Linux 2.6.24)
	      This enables or disables killing the OOM-triggering task in out-
	      of-memory situations.

	      If this is set to zero, the OOM-killer  will  scan  through  the
	      entire  tasklist	and select a task based on heuristics to kill.
	      This normally selects a rogue memory-hogging task that frees  up
	      a large amount of memory when killed.

	      If  this is set to nonzero, the OOM-killer simply kills the task
	      that triggered the out-of-memory condition.  This avoids a  pos‐
	      sibly expensive tasklist scan.

	      If  /proc/sys/vm/panic_on_oom  is	 nonzero,  it takes precedence
	      over whatever value is  used  in	/proc/sys/vm/oom_kill_allocat‐
	      ing_task.

	      The default value is 0.

       /proc/sys/vm/overcommit_memory
	      This  file  contains  the kernel virtual memory accounting mode.
	      Values are:

		     0: heuristic overcommit (this is the default)
		     1: always overcommit, never check
		     2: always check, never overcommit

	      In mode 0, calls of mmap(2) with MAP_NORESERVE are not  checked,
	      and  the default check is very weak, leading to the risk of get‐
	      ting a process "OOM-killed".  Under Linux 2.4 any nonzero	 value
	      implies  mode  1.	  In  mode  2 (available since Linux 2.6), the
	      total virtual address space on the system is limited  to	(SS  +
	      RAM*(r/100)), where SS is the size of the swap space, and RAM is
	      the size of the physical memory, and r is the  contents  of  the
	      file /proc/sys/vm/overcommit_ratio.

       /proc/sys/vm/overcommit_ratio
	      See the description of /proc/sys/vm/overcommit_memory.

       /proc/sys/vm/panic_on_oom (since Linux 2.6.18)
	      This enables or disables a kernel panic in an out-of-memory sit‐
	      uation.

	      If this file is set to the value 0, the kernel's OOM-killer will
	      kill  some  rogue	 process.   Usually, the OOM-killer is able to
	      kill a rogue process and the system will survive.

	      If this file is set to the value 1,  then	 the  kernel  normally
	      panics when out-of-memory happens.  However, if a process limits
	      allocations to certain nodes  using  memory  policies  (mbind(2)
	      MPOL_BIND)  or  cpusets (cpuset(7)) and those nodes reach memory
	      exhaustion status, one process may be killed by the  OOM-killer.
	      No panic occurs in this case: because other nodes' memory may be
	      free, this means the system as a whole may not have  reached  an
	      out-of-memory situation yet.

	      If  this	file  is  set to the value 2, the kernel always panics
	      when an out-of-memory condition occurs.

	      The default value is 0.  1 and 2 are for failover of clustering.
	      Select either according to your policy of failover.

       /proc/sys/vm/swappiness
	      The value in this file controls how aggressively the kernel will
	      swap memory pages.  Higher values increase aggressiveness, lower
	      values decrease aggressiveness.  The default value is 60.

       /proc/sysrq-trigger (since Linux 2.4.21)
	      Writing  a  character to this file triggers the same SysRq func‐
	      tion as typing ALT-SysRq-<character>  (see  the  description  of
	      /proc/sys/kernel/sysrq).	This file is normally writable only by
	      root.  For further details see the Linux kernel source file Doc‐
	      umentation/sysrq.txt.

       /proc/sysvipc
	      Subdirectory  containing	the  pseudo-files  msg,	 sem  and shm.
	      These files list the System V Interprocess  Communication	 (IPC)
	      objects  (respectively:  message	queues, semaphores, and shared
	      memory) that currently exist on the  system,  providing  similar
	      information  to  that  available	via ipcs(1).  These files have
	      headers and are formatted (one IPC object	 per  line)  for  easy
	      understanding.   svipc(7)	 provides  further  background	on the
	      information shown by these files.

       /proc/tty
	      Subdirectory containing the pseudo-files and subdirectories  for
	      tty drivers and line disciplines.

       /proc/uptime
	      This  file  contains two numbers: the uptime of the system (sec‐
	      onds), and the amount of time spent in idle process (seconds).

       /proc/version
	      This string identifies the kernel version that is currently run‐
	      ning.   It  includes  the	 contents  of /proc/sys/kernel/ostype,
	      /proc/sys/kernel/osrelease  and  /proc/sys/kernel/version.   For
	      example:
	    Linux version 1.0.9 (quinlan@phaze) #1 Sat May 14 01:51:54 EDT 1994

       /proc/vmstat (since Linux 2.6)
	      This file displays various virtual memory statistics.

       /proc/zoneinfo (since Linux 2.6.13)
	      This  file display information about memory zones.  This is use‐
	      ful for analyzing virtual memory behavior.

NOTES
       Many strings (i.e., the environment and command line) are in the inter‐
       nal  format, with subfields terminated by null bytes ('\0'), so you may
       find that things are more readable if you use od -c or tr  "\000"  "\n"
       to read them.  Alternatively, echo `cat <file>` works well.

       This manual page is incomplete, possibly inaccurate, and is the kind of
       thing that needs to be updated very often.

SEE ALSO
       cat(1), dmesg(1), find(1), free(1), ps(1), tr(1), uptime(1), chroot(2),
       mmap(2), readlink(2), syslog(2), slabinfo(5), hier(7), time(7), arp(8),
       hdparm(8), ifconfig(8), init(8),	 lsmod(8),  lspci(8),  mount(8),  net‐
       stat(8), procinfo(8), route(8), sysctl(8)

       The Linux kernel source files: Documentation/filesystems/proc.txt Docu‐
       mentation/sysctl/fs.txt,	 Documentation/sysctl/kernel.txt,   Documenta‐
       tion/sysctl/net.txt, and Documentation/sysctl/vm.txt.

COLOPHON
       This  page  is  part of release 3.63 of the Linux man-pages project.  A
       description of the project, and information about reporting  bugs,  can
       be found at http://www.kernel.org/doc/man-pages/.

Linux				  2014-03-17			       PROC(5)
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