mktemp man page on JazzOS

Man page or keyword search:  
man Server   2339 pages
apropos Keyword Search (all sections)
Output format
JazzOS logo
[printable version]

MKTEMP(1)							     MKTEMP(1)

       mktemp - make temporary filename (unique)

       mktemp [-V] | [-dqtu] [-p directory] [template]

       The  mktemp  utility takes the given filename template and overwrites a
       portion of it to create a unique filename.  The	template  may  be  any
       filename	 with  some  number  of	 `Xs'  appended	 to  it,  for  example
       /tmp/tfile.XXXXXXXXXX.  If  no  template	 is  specified	a  default  of
       tmp.XXXXXXXXXX is used and the -t flag is implied (see below).

       The  trailing  `Xs'  are	 replaced  with	 a  combination of the current
       process number and random letters.  The name chosen depends both on the
       number  of  `Xs'	 in  the  template  and	 the number of collisions with
       pre-existing files.  The number of unique filenames mktemp  can	return
       depends	on the number of `Xs' provided; ten `Xs' will result in mktemp
       testing roughly 26 ** 10 combinations.

       If mktemp can successfully generate a unique  filename,	the  file  (or
       directory)  is created with file permissions such that it is only read‐
       able and writable by its owner (unless the -u flag is  given)  and  the
       filename is printed to standard output.

       mktemp  is  provided  to	 allow	shell  scripts to safely use temporary
       files.  Traditionally, many shell scripts take the name of the  program
       with  the  PID  as a suffix and use that as a temporary filename.  This
       kind of naming scheme is predictable and the race condition it  creates
       is  easy	 for  an  attacker  to	win.   A  safer, though still inferior
       approach is to make a temporary directory using the same naming scheme.
       While  this  does allow one to guarantee that a temporary file will not
       be subverted, it still allows a simple denial of service	 attack.   For
       these reasons it is suggested that mktemp be used instead.

       The options are as follows:

       -V     Print the version and exit.

       -d     Make a directory instead of a file.

       -p directory
	      Use the specified directory as a prefix when generating the tem‐
	      porary filename.	The directory will be overridden by the user's
	      TMPDIR  environment  variable if it is set.  This option implies
	      the -t flag (see below).

       -q     Fail silently if an error occurs.	 This is useful	 if  a	script
	      does not want error output to go to standard error.

       -t     Generate a path rooted in a temporary directory.	This directory
	      is chosen as follows:

	      ·	     If the user's TMPDIR environment  variable	 is  set,  the
		     directory contained therein is used.

	      ·	     Otherwise,	 if the -p flag was given the specified direc‐
		     tory is used.

	      ·	     If none of the above apply, /tmp is used.

       In this mode, the template (if specified) should be a directory	compo‐
       nent  (as  opposed to a full path) and thus should not contain any for‐
       ward slashes.

       -u     Operate in ``unsafe'' mode.  The	temp  file  will  be  unlinked
	      before mktemp exits.  This is slightly better than mktemp(3) but
	      still introduces a race condition.  Use of this  option  is  not

       The mktemp utility exits with a value of 0 on success or 1 on failure.

       TMPDIR  directory in which to place the temporary file when in -t mode

       The  following  sh(1) fragment illustrates a simple use of mktemp where
       the script should quit if it cannot get a safe temporary file.

	      TMPFILE=`mktemp /tmp/example.XXXXXXXXXX` || exit 1
	      echo "program output" >> $TMPFILE

       The same fragment with support for a user's TMPDIR environment variable
       can be written as follows.

	      TMPFILE=`mktemp -t example.XXXXXXXXXX` || exit 1
	      echo "program output" >> $TMPFILE

       This  can  be further simplified if we don't care about the actual name
       of the temporary file.  In this case the -t flag is implied.

	      TMPFILE=`mktemp` || exit 1
	      echo "program output" >> $TMPFILE

       In some cases, it may be desirable to use a default temporary directory
       other than /tmp.	 In this example the temporary file will be created in
       /extra/tmp unless the user's TMPDIR environment variable specifies oth‐

	      TMPFILE=`mktemp -p /extra/tmp example.XXXXXXXXXX` || exit 1
	      echo "program output" >> $TMPFILE

       In some cases, we want the script to catch the error.  For instance, if
       we attempt to create two temporary files and the second	one  fails  we
       need to remove the first before exiting.

	      TMP1=`mktemp -t example.1.XXXXXXXXXX` || exit 1
	      TMP2=`mktemp -t example.2.XXXXXXXXXX`
	      if [ $? -ne 0 ]; then
		   rm -f $TMP1
		   exit 1

       Or  perhaps  you	 don't	want to exit if mktemp is unable to create the
       file.  In this case you can protect that part of the script thusly.

	      TMPFILE=`mktemp -t example.XXXXXXXXXX` && {
		   # Safe to use $TMPFILE in this block
		   echo data > $TMPFILE
		   rm -f $TMPFILE

       mkdtemp(3), mkstemp(3), mktemp(3)

       The mktemp utility appeared in OpenBSD 2.1.

			       30 September 2001		     MKTEMP(1)

List of man pages available for JazzOS

Copyright (c) for man pages and the logo by the respective OS vendor.

For those who want to learn more, the polarhome community provides shell access and support.

[legal] [privacy] [GNU] [policy] [cookies] [netiquette] [sponsors] [FAQ]
Polarhome, production since 1999.
Member of Polarhome portal.
Based on Fawad Halim's script.
Vote for polarhome
Free Shell Accounts :: the biggest list on the net