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MKTEMP(1)		FreeBSD	General	Commands Manual		     MKTEMP(1)

     mktemp -- make temporary file name	(unique)

     mktemp [-d] [-p tmpdir] [-q] [-t prefix] [-u] template ...
     mktemp [-d] [-p tmpdir] [-q] [-u] -t prefix

     The mktemp	utility	takes each of the given	file name templates and	over-
     writes a portion of it to create a	file name.  This file name is unique
     and suitable for use by the application.  The template may	be any file
     name with some number of `Xs' appended to it, for example /tmp/temp.XXXX.
     The trailing `Xs' are replaced with the current process number and/or a
     unique letter combination.	 The number of unique file names mktemp	can
     return depends on the number of `Xs' provided; six	`Xs' will result in
     mktemp selecting 1	of 56800235584 (62 ** 6) possible file names.

     If	mktemp can successfully	generate a unique file name, the file is cre-
     ated with mode 0600 (unless the -u	flag is	given) and the filename	is
     printed to	standard output.

     If	the -t prefix option is	given, mktemp will generate a template string
     based on the prefix and the TMPDIR	environment variable if	set.  If the
     -p	option is set, then the	given tmpdir will be used if the TMPDIR	envi-
     ronment variable is not set.  Finally, /tmp will be used if neither
     TMPDIR or -p are set and used.  Care should be taken to ensure that it is
     appropriate to use	an environment variable	potentially supplied by	the

     If	no arguments are passed	or if only the -d flag is passed mktemp	be-
     haves as if -t tmp	was supplied.

     Any number	of temporary files may be created in a single invocation, in-
     cluding one based on the internal template	resulting from the -t flag.

     The mktemp	utility	is provided to allow shell scripts to safely use tem-
     porary files.  Traditionally, many	shell scripts take the name of the
     program with the pid as a suffix and use that as a	temporary file name.
     This kind of naming scheme	is predictable and the race condition it cre-
     ates is easy for an attacker to win.  A safer, though still inferior, ap-
     proach 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 available options are as follows:

     -d, --directory
	     Make a directory instead of a file.

     -p	tmpdir,	--tmpdir[=tmpdir]
	     Use tmpdir	for the	-t flag	if the TMPDIR environment variable is
	     not set.  Additionally, any provided template arguments will be
	     interpreted relative to the path specified	as tmpdir.  If tmpdir
	     is	either empty or	omitted, then the TMPDIR environment variable
	     will be used.

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

     -t	prefix
	     Generate a	template (using	the supplied prefix and	TMPDIR if set)
	     to	create a filename template.

     -u, --dry-run
	     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 encour-

     The mktemp	utility	exits 0	on success, and	>0 if an error occurs.

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

	   tempfoo=`basename $0`
	   TMPFILE=`mktemp /tmp/${tempfoo}.XXXXXX` || exit 1
	   echo	"program output" >> $TMPFILE

     To	allow the use of $TMPDIR:

	   tempfoo=`basename $0`
	   TMPFILE=`mktemp -t ${tempfoo}` || exit 1
	   echo	"program output" >> $TMPFILE

     In	this case, we want the script to catch the error itself.

	   tempfoo=`basename $0`
	   TMPFILE=`mktemp -q /tmp/${tempfoo}.XXXXXX`
	   if [	$? -ne 0 ]; then
		   echo	"$0: Can't create temp file, exiting..."
		   exit	1

     mkdtemp(3), mkstemp(3), mktemp(3),	environ(7)

     A mktemp utility appeared in OpenBSD 2.1.	This implementation was	writ-
     ten independently based on	the OpenBSD man	page, and first	appeared in
     FreeBSD 2.2.7.  This man page is taken from OpenBSD.

FreeBSD	13.0			August 4, 2022			  FreeBSD 13.0


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