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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:
               _BSD_SOURCE || _SVID_SOURCE ||
                   (_XOPEN_SOURCE >= 500 ||
                        _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED) &&
                   !(_POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE >= 600)
           Before glibc 2.12:
               _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500 ||
               _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED

DESCRIPTION

       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.

ERRORS

       EINVAL The last six characters of template were not XXXXXX.

CONFORMING TO

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

NOTES

       The prototype is in <unistd.h> for libc4, libc5, glibc1; glibc2 follows
       the Single UNIX Specification and has the prototype in <stdlib.h>.

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).

SEE ALSO

       mkstemp(3), tempnam(3), tmpfile(3), tmpnam(3)

COLOPHON

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