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mktemp(3) — Linux manual page

NAME \|LIBRARY \|SYNOPSIS \|DESCRIPTION \|RETURN VALUE \|ERRORS \|ATTRIBUTES \|STANDARDS \|HISTORY \|BUGS \|SEE ALSO \|COLOPHON

mktemp(3)                Library Functions Manualmktemp(3)

NAME top

       mktemp - make a unique temporary filename

LIBRARY top

       Standard C library (libc,-lc)

SYNOPSIS top

#include <stdlib.h>char *mktemp(char *template);   Feature Test Macro Requirements for glibc (seefeature_test_macros(7)):mktemp():           Since glibc 2.12:               (_XOPEN_SOURCE >= 500) && ! (_POSIX_C_SOURCE >= 200112L)                   || /* glibc >= 2.19: */ _DEFAULT_SOURCE                   || /* glibc <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE           Before glibc 2.12:               _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500

DESCRIPTION top

Never use this function; see BUGS.       Themktemp() function generates a unique temporary filename fromtemplate.  The last six characters oftemplate 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.

RETURN VALUE top

       Themktemp() function always returnstemplate.  If a unique name       was created, the last six bytes oftemplate 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 string, anderrno is set to indicate the       error.

ERRORS top

EINVALThe last six characters oftemplate were not XXXXXX.

ATTRIBUTES top

       For an explanation of the terms used in this section, seeattributes(7).       ┌──────────────────────────────────────┬───────────────┬─────────┐       │Interface│Attribute│Value│       ├──────────────────────────────────────┼───────────────┼─────────┤       │mktemp()                             │ Thread safety │ MT-Safe │       └──────────────────────────────────────┴───────────────┴─────────┘

STANDARDS top

       None.

HISTORY top

       4.3BSD, POSIX.1-2001.  Removed in POSIX.1-2008.

BUGS top

       Never usemktemp().  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 testing whether the name exists and opening the file,       every use ofmktemp() is a security risk.  The race is avoided bymkstemp(3) andmkdtemp(3).

COLOPHON top

       This page is part of theman-pages (Linux kernel and C library       user-space interface documentation) project.  Information about       the project can be found at        ⟨https://www.kernel.org/doc/man-pages/⟩.  If you have a bug report       for this manual page, see       ⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.       This page was obtained from the tarball man-pages-6.15.tar.gz       fetched from       ⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on       2025-08-11.  If you discover any rendering problems in this HTML       version of the page, or you believe there is a better or more up-       to-date source for the page, or you have corrections or       improvements to the information in this COLOPHON (which isnot       part of the original manual page), send a mail to       man-pages@man7.orgLinux man-pages 6.15            2025-05-17mktemp(3)

Pages that refer to this page:mktemp(1), mkdtemp(3), mkstemp(3), pmrecord(3), stdio(3), tempnam(3), tmpfile(3), tmpnam(3)

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