Open Source Software

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
   template.  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
   attributes(7).

   
   Interface  Attribute      Value   
   
   mktemp()   Thread safety  MT-Safe

CONFORMING TO

   4.3BSD,  POSIX.1-2001.   POSIX.1-2008  removes  the  specification   of
   mktemp().

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
   testing  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 4.09 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/.



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