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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
     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  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).