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mktemp(1) |
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MKTEMP(1) BSD General Commands Manual MKTEMP(1)
NAME
mktemp — make temporary file name (unique)
SYNOPSIS
mktemp [−q] [−u] template
DESCRIPTION
The mktemp utility takes the given file name template 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 six ’Xs’ appended to it, for example /tmp/temp.XXXXXX. The trailing ’Xs’ are replaced with the current process number and/or a unique letter combination.
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.
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 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:
−q
Fail silently if an error occurs. This is useful if a script does not want error output to go to standard error.
−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.
RETURN VALUES
The mktemp utility exits with a value of 0 on success or 1 on failure.
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.
TMPFILE=’mktemp
/tmp/$0.XXXXXX’ || exit 1
echo "program output" >> $TMPFILE
In this case, we want the script to catch the error itself.
TMPFILE=’mktemp
-q /tmp/$0.XXXXXX’
if [ $? -ne 0 ]; then
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echo "$0: Can’t create temp file, exiting..." |
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exit 1 |
fi
SEE ALSO
mkstemp(3), mktemp(3)
HISTORY
The mktemp utility appeared in OpenBSD.
BSD November 20, 1996 BSD
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mktemp(1) | |