mktemp(3)



MKTEMP(3)                  Linux Programmer's Manual                 MKTEMP(3)

NAME
       mktemp - make a unique temporary filename

SYNOPSIS
       #include <stdlib.h>

       char *mktemp(char *template);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       mktemp():
           Since glibc 2.12:
               (_XOPEN_SOURCE >= 500) && ! (_POSIX_C_SOURCE >= 200112L)
                   || /* Glibc since 2.19: */ _DEFAULT_SOURCE
                   || /* Glibc <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE
           Before glibc 2.12:
               _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500

DESCRIPTION
       Never use this function; see BUGS.

       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.

RETURN VALUE
       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
       string, and errno is set to indicate the error.

ERRORS
       EINVAL The last six characters of template were not XXXXXX.

ATTRIBUTES
       For  an  explanation  of  the  terms  used  in  this  section,  see at-
       tributes(7).

       +----------+---------------+---------+
       |Interface | Attribute     | Value   |
       +----------+---------------+---------+
       |mktemp()  | Thread safety | MT-Safe |
       +----------+---------------+---------+
CONFORMING TO
       4.3BSD, POSIX.1-2001.  POSIX.1-2008 removes the  specification  of  mk-
       temp().

BUGS
       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) and mkdtemp(3).

SEE ALSO
       mktemp(1), mkdtemp(3), mkstemp(3), tempnam(3), tmpfile(3), tmpnam(3)

COLOPHON
       This page is part of release 4.16 of the Linux  man-pages  project.   A
       description  of  the project, information about reporting bugs, and the
       latest    version    of    this    page,    can     be     found     at
       https://www.kernel.org/doc/man-pages/.

GNU                               2017-09-15                         MKTEMP(3)

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