MKTEMP(3) Linux Programmer's Manual MKTEMP(3)
mktemp - make a unique temporary filename
char *mktemp(char *template);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
mktemp(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500
The mktemp() function generates a unique temporary filename from tem-
plate. The last six characters of template must be XXXXXX and these
are replaced with a string that makes the filename unique. Since it
will be modified, template must not be a string constant, but should be
declared as a character array.
The mktemp() function always returns template. If a unique name was
created, the last six bytes of template will have been modified in such
a way that the resulting name is unique (i.e., does not exist already)
If a unique name could not be created, template is made an empty
EINVAL The last six characters of template were not XXXXXX.
4.3BSD, POSIX.1-2001. POSIX.1-2008 removes the specification of
The prototype is in for libc4, libc5, glibc1; glibc2 follows
the Single Unix Specification and has the prototype in .
Never use mktemp(). Some implementations follow 4.3BSD and replace
XXXXXX by the current process ID and a single letter, so that at most
26 different names can be returned. Since on the one hand the names
are easy to guess, and on the other hand there is a race between test-
ing whether the name exists and opening the file, every use of mktemp()
is a security risk. The race is avoided by mkstemp(3).
mkstemp(3), tempnam(3), tmpfile(3), tmpnam(3)
This page is part of release 3.22 of the Linux man-pages project. A
description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
GNU 2008-08-06 MKTEMP(3)