MKTEMP(1)						    BSD General Commands Manual 						 MKTEMP(1)

NAME

     mktemp -- make temporary file name (unique)

SYNOPSIS

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

DESCRIPTION

     The mktemp utility takes each of the given file name templates and overwrites 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) pos-
     sible file names.	On case-insensitive file systems, the effective number of unique names is significantly less; given six 'Xs', mktemp will
     instead select 1 of 2176782336 (36 ** 6) possible unique file names.

     If mktemp can successfully generate a unique file name, the file is created 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 _CS_DARWIN_USER_TEMP_DIR configuration
     variable if available.  Fallback locations if _CS_DARWIN_USER_TEMP_DIR is not available are TMPDIR and /tmp.  Care should be taken to ensure
     that it is appropriate to use an environment variable potentially supplied by the user.

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

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

     The mktemp utility 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 file name.  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.

OPTIONS

     The available options are as follows:

     -d      Make a directory instead of a file.

     -q      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      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 encouraged.

EXIT STATUS

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

EXAMPLES

     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
	   fi

SEE ALSO

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

HISTORY

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

BSD
								 December 30, 2005							       BSD