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       mkstemp - create a unique temporary file


       #include <stdlib.h>

       int mkstemp(char *template);


       The  mkstemp()  function  generates  a  unique temporary file name from
       template.  The last six characters of template must be XXXXXX and these
       are  replaced with a string that makes the filename unique. The file is
       then created with mode read/write and permissions 0666 (glibc 2.0.6 and
       earlier),  0600  (glibc  2.0.7  and later).  Since it will be modified,
       template must not be a string constant, but should  be  declared  as  a
       character array.  The file is opened with the O_EXCL flag, guaranteeing
       that when mkstemp() returns successfully we are the only user.


       On success, the mkstemp() function returns the file descriptor  of  the
       temporary   file.    On  error,  -1  is  returned,  and  errno  is  set


       EEXIST Could not create a unique temporary filename.  Now the  contents
              of template are undefined.

       EINVAL The  last  six  characters  of  template  were  not XXXXXX.  Now
              template is unchanged.


       The old behaviour (creating a file with mode 0666) may  be  a  security
       risk, especially since other Unix flavours use 0600, and somebody might
       overlook this detail when porting programs.

       More generally, the POSIX specification does  not  say  anything  about
       file  modes,  so  the  application  should  make  sure its umask is set
       appropriately before calling mkstemp().


       4.3BSD, POSIX 1003.1-2001


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

       Don’t  use this function, use tmpfile(3) instead.  It is better defined
       and more portable.


       mkdtemp(3), mktemp(3), tempnam(3), tmpfile(3), tmpnam(3)