errno(2)errno(2)NAMEerrno - error indicator for function calls
Many functions in the HP-UX operating system indicate an error condi‐
tion by returning an otherwise out-of-range value (usually Most of
these functions set the symbol that is defined in to a nonzero code
value that more specifically identifies the particular error condition
that was encountered.
In most cases, the manpages for functions that set list those values
and error descriptions in the ERRORS section of the manpages. However,
failures in underlying functions, subsystems, and applications may
return values that are not documented in the calling functions' man‐
The value of is zero immediately after a successful call to any of the
functions described by exec(2), but it is never set to zero by any
other HP-UX function. Functions for which the use of is not described
may nevertheless change its value to a nonzero value.
Since is not cleared on successful function calls, its value should be
checked or used only when an error has been indicated and when the
function's section documents the error codes.
Applications should not attempt to take the address of The practice of
defining as is obsolescent.
The following is a complete list of the error codes. The numeric val‐
ues can be found in but they should not be used in an application pro‐
gram because they can vary from system to system.
[E2BIG] Arg list too long. An argument and or environment list
longer than maximum supported size is presented to a
member of the family. Other possibilities include: mes‐
sage size or number of semaphores exceeds system limit
or too many privileged groups have been set up
[EACCES] Permission denied. An attempt was made to access a file
or IPC object in a way forbidden by the protection sys‐
[EADDRINUSE] Address already in use. Only one usage of each address
is normally permitted.
Cannot assign requested address. Normally results from
an attempt to create a socket with an address not on
[EAFNOSUPPORT] Address family not supported by protocol family. An
address incompatible with the requested protocol was
used. For example, you should not necessarily expect to
be able to use PUP Internet addresses with ARPA Internet
[EAGAIN] Resource temporarily unavailable. This is likely a tem‐
porary condition, and later calls to the same routine
may complete normally.
[EALREADY] Operation already in progress. An operation was
attempted on a nonblocking object which already had an
operation in progress.
[EBADF] Bad file number. Either a file descriptor refers to no
open file, a read (respectively write) request is made
to a file which is open only for writing (respectively
reading), or the file descriptor is not in the legal
range of file descriptors.
[EBUSY] Device or resource busy. An attempt to mount a device
that was already mounted or an attempt was made to dis‐
mount a device on which there is an active file (open
file, current directory, mounted-on file, active text
segment). It will also occur if an attempt is made to
enable accounting when it is already enabled. The
device or resource is currently unavailable, such as
when a nonsharable device file is in use.
[ECHILD] No child processes. A was executed by a process that
had no existing or unwaited-for child processes.
[ECONNABORTED] Software caused connection abort. A connection abort
was caused internal to your host machine.
[ECONNREFUSED] Connection refused. No connection could be made because
the target machine actively refused it. This usually
results from trying to connect to a service that is
inactive on the foreign host.
[ECONNRESET] Connection reset by peer. A connection was forcibly
closed by a peer. This normally results from the peer
executing a call (see shutdown(2)).
[EDEADLK] Resource deadlock would occur. A process which has
locked a system resource would have been put to sleep
while attempting to access another process' locked
[EDESTADDRREQ] Destination address required. A required address was
omitted from an operation on a socket.
[EDOM] Math argument. The argument of a function in the math
package (3M) is out of the domain of the function.
[EEXIST] File exists. An existing file was mentioned in an inap‐
propriate context; e.g.,
[EFAULT] Bad address. The system encountered a hardware fault in
attempting to use an argument of a system call; can also
result from passing the wrong number of parameters to a
system call. The reliable detection of this error is
[EFBIG] File too large. The size of a file exceeded the maximum
file size (for the file system) or was exceeded (see
ulimit(2)), or a bad semaphore number in a call (see
[EHOSTDOWN] Host is down. A socket operation encountered a dead
host. Networking activity on the local host has not
[EHOSTUNREACH] No route to host. A socket operation was attempted to
an unreachable host.
[EIDRM] Identifier Removed. This error is returned to processes
that resume execution due to the removal of an identi‐
fier from the file system's name space (see msgctl(2),
semctl(2), and shmctl(2)).
[EILSEQ] Illegal byte sequence. A wide character code has been
detected that does not correspond to a valid character,
or a byte sequence does not form a valid wide character
[EINPROGRESS] Operation now in progress. An operation that takes a
long time to complete was attempted on a nonblocking
object (see ioctl(2) and fcntl(2)).
[EINTR] Interrupted system call. An asynchronous signal (such
as interrupt or quit), which the user has elected to
catch, occurred during a system call. If execution is
resumed after processing the signal, it will appear as
if the interrupted system call returned this error con‐
dition unless the system call is restarted (see sig‐
[EINVAL] Invalid argument. Some invalid argument (such as
unmounting a device that is not currently mounted, men‐
tioning an undefined signal in or or reading or writing
a file for which has generated a negative pointer).
Also set by the math functions described in the (3M)
entries of this manual.
[EIO] I/O error − some physical I/O error. This error may in
some cases occur on a call following the one to which it
[EISCONN] Socket is already connected. A request was made on an
already connected socket, or, a or request on a con‐
nected socket specified a destination other than the
[EISDIR] Is a directory. An attempt to open a directory for
[ELOOP] Too many levels of symbolic links were encountered while
resolving a path name. See fs_symlinks(5) for more
[EMFILE] Too many open files. No process may have more than a
system-defined number of file descriptors open at a
[EMLINK] Too many links. An attempt to make more than the maxi‐
mum number of links to a file.
[EMSGSIZE] Message too long. The socket requires that the message
be sent atomically, and the size of the message to be
sent made this impossible.
[ENAMETOOLONG] File name too long. A path specified exceeds the maxi‐
mum path length for the system. The maximum path length
is specified by and is defined in PATH_MAX is guaranteed
to be at least 1023 bytes. This error is also generated
if the length of a path name component exceeds and the
option is in effect for the specified path. Currently,
is in effect only for HFS file systems configured to
allow path name components up to 255 bytes long (see
convertfs(1M)) and therefore only path names referring
to such file systems can generate the error for this
case. The values of and for a particular path name can
be queried by using the system call (see pathconf(2)).
[ENETDOWN] Network is down. A socket operation encountered a dead
[ENETRESET] Network dropped connection on reset. The host you were
connected to crashed and rebooted.
[ENETUNREACH] Network is unreachable. A socket operation was
attempted to an unreachable network.
[ENFILE] File table overflow. The system's table of open files
is full, and temporarily no more can be accepted.
[ENOBUFS] No buffer space available. An operation on a socket was
not performed because the system lacked sufficient buf‐
[ENODEV] No such device. An attempt was made to apply an inap‐
propriate system call to a device (such as read a write-
[ENOENT] No such file or directory. This error occurs when a
file name is specified and the file should exist but
does not, or when one of the directories in a path name
does not exist. It also occurs with and when key does
not refer to any object and the flag is not set.
[ENOEXEC] Exec format error. A request is made to execute a file
which, although it has the appropriate permissions, does
not start with a valid magic number (see a.out(4)), or
the file is too small to have a valid executable file
[ENOLCK] System lock table is full. Too many files have file
locks on them, or there are too many record locks on
files, or there are too many instances of a reading or
writing process sleeping until an enforcement mode lock
clears. This error may also indicate system problems in
handling a lock request on a remote NFS file. This
error is also currently returned for all attempts to
perform locking operations on a remote NFS file that has
its locking enforcement mode bit set, since the state‐
less nature of NFS prevents maintaining the necessary
[ENOLINK] No connection. The link with the device has been severed
[ENOMEM] Not enough space. During a system call such as or a
program asks for more space than the system is able to
supply. This may not be a temporary condition; the max‐
imum space size is a system parameter. The error can
also occur if there is not enough swap space during a
[ENOMSG] No message of desired type. An attempt was made to
receive a message of a type that does not exist on the
specified message queue; see msgop(2).
[ENOPROTOOPT] Protocol option not available. This may be returned for
a or call (see getsockopt(2)) if the user specified an
option that the local system does not support or for any
system call that causes the local system to send a net‐
work protocol option that a remote system does not sup‐
port, including a system call that operates on an NFS
[ENOSPC] No space left on device. During a to an ordinary file,
there is no free space left on the device; or no space
in system table during or while flag is set.
[ENOSYM] Symbol does not exist in executable. The dynamic loader
was unable to resolve a symbolic reference in a shared
library during a call to one of the dynamic loader
interface routines (see shl_load(3X). The program may
be in an inconsistent state and should be terminated
[ENOSYS] Function is not available. The requested function or
operation is not implemented or not configured in the
[ENOTBLK] Block device required. A nonblock file was mentioned
where a block device was required, such as in
[ENOTCONN] Socket is not connected. A request to send or receive
data was disallowed because the socket was not con‐
[ENOTDIR] Not a directory. A nondirectory was specified where a
directory is required, such as in a path prefix or as an
[ENOTEMPTY] Directory not empty. An attempt was made to remove a
[ENOTSOCK] Socket operation on nonsocket. An operation was
attempted on something that is not a socket.
[ENOTTY] Not a typewriter. The command is inappropriate to the
selected device type.
[ENXIO] No such device or address. I/O on a special file refers
to a subdevice that does not exist, or is beyond the
limits of the device. It can also occur when, for exam‐
ple, a tape drive is not on line or no disk pack is
loaded on a drive.
[EOPNOTSUPP] Operation not supported. The requested operation on a
socket or NFS file is either invalid or unsupported.
For example, this might occur when an attempt to a con‐
nection on a datagram socket fails.
[EPERM] Not owner. Typically, this error indicates an attempt
to modify a file in some way forbidden except to its
owner or the superuser, such as to change its mode. It
is also returned for attempts by ordinary users to do
things for which they need, but lack, a special privi‐
[EPFNOSUPPORT] Protocol family not supported. The protocol family has
not been configured into the system or no implementation
for it exists. The socket is not connected.
[EPIPE] Broken pipe. Data has been written to a pipe for which
the other (reading) end has been closed. This most
often occurs when the reading process exits before the
writing process. This condition also generates the sig‐
nal the error is returned if the signal is ignored.
Protocol not supported. The protocol has not been con‐
figured into the system or no implementation for it
[EPROTOTYPE] Protocol wrong type for socket. A protocol was speci‐
fied that does not support the semantics of the socket
type requested. For example, ARPA Internet UDP protocol
cannot be used with type
[ERANGE] Result too large. The value of a function in the math
package (3M) is not representable within machine preci‐
sion, or a call would cause either a semaphore value or
a semaphore adjust value to exceed it system-imposed
[EROFS] Read-only file system. An attempt to modify a file or
directory was made on a device mounted read-only.
[ESHUTDOWN] Cannot send after socket shutdown. A request to send
data was disallowed because the socket had already been
shut down with a previous call.
Socket type not supported. The support for the socket
type has not been configured into the system or no
implementation for it exists.
[ESPIPE] Illegal seek. An was issued to a pipe.
[ESRCH] No such process. No process can be found corresponding
to that specified by pid in or or the process is not
[ETIMEDOUT] Connection timed out. A request failed because the con‐
nected party did not properly respond after a period of
time (timeout period varies, depending on the communica‐
[ETXTBSY] Text file busy. An attempt to execute an executable
file which is currently open for writing (or reading).
Also, an attempt to open for writing an otherwise
writable file which is currently open for execution.
[EWOULDBLOCK] Operation would block. An operation which would cause a
process to block was attempted on an object in nonblock‐
ing mode (see ioctl(2) and fcntl(2)).
[EXDEV] Cross-device link. A link to a file on another device
The following NFS errors are also defined:
[EREFUSED] The same error as The external variable is
defined as for NFS compatibility.
[EREMOTE] Too many levels of remote in path. An attempt
was made to remotely mount an NFS file system
into a path which already has a remotely mounted
NFS file system component.
[ESTALE] Stale NFS file handle. A client referenced an
open file, but the file was previously deleted.