tmpnam(3)

NAME

   tmpnam, tmpnam_r - create a name for a temporary file

SYNOPSIS

   #include <stdio.h>

   char *tmpnam(char *s);
   char *tmpnam_r(char *s);

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

   tmpnam_r()
       Since glibc 2.19:
           _DEFAULT_SOURCE
       Up to and including glibc 2.19:
           _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION

   Note:  avoid  using  these  functions;  use  mkstemp(3)  or  tmpfile(3)
   instead.

   The tmpnam() function returns a pointer to a string  that  is  a  valid
   filename,  and  such  that  a file with this name did not exist at some
   point in time, so that naive programmers may think it a  suitable  name
   for  a  temporary  file.   If  the  argument  s  is  NULL, this name is
   generated in an internal static buffer and may be  overwritten  by  the
   next  call  to  tmpnam().   If s is not NULL, the name is copied to the
   character array (of length at least L_tmpnam) pointed to by s  and  the
   value s is returned in case of success.

   The  created  pathname has a directory prefix P_tmpdir.  (Both L_tmpnam
   and P_tmpdir are defined in <stdio.h>, just like the TMP_MAX  mentioned
   below.)

   The tmpnam_r() function performs the same task as tmpnam(), but returns
   NULL (to indicate an error) if s is NULL.

RETURN VALUE

   These functions return a pointer to a  unique  temporary  filename,  or
   NULL if a unique name cannot be generated.

ERRORS

   No errors are defined.

ATTRIBUTES

   For   an   explanation   of   the  terms  used  in  this  section,  see
   attributes(7).

   
   Interface   Attribute      Value                    
   
   tmpnam()    Thread safety  MT-Unsafe race:tmpnam/!s 
   
   tmpnam_r()  Thread safety  MT-Safe                  
   

CONFORMING TO

   tmpnam(): SVr4, 4.3BSD, C89,  C99,  POSIX.1-2001.   POSIX.1-2008  marks
   tmpnam() as obsolete.

   tmpnam_r()  is  a nonstandard extension that is also available on a few
   other systems.

NOTES

   The tmpnam() function generates a different  string  each  time  it  is
   called,  up to TMP_MAX times.  If it is called more than TMP_MAX times,
   the behavior is implementation defined.

   Although these functions generate names that are difficult to guess, it
   is  nevertheless  possible  that  between the time that the pathname is
   returned and the time that the program opens it, another program  might
   create  that  pathname  using open(2), or create it as a symbolic link.
   This can lead to security holes.  To avoid such possibilities, use  the
   open(2)  O_EXCL  flag  to  open  the  pathname.   Or  better  yet,  use
   mkstemp(3) or tmpfile(3).

   Portable applications that use threads cannot call tmpnam() with a NULL
   argument  if  either  _POSIX_THREADS or _POSIX_THREAD_SAFE_FUNCTIONS is
   defined.

BUGS

   Never use these functions.  Use mkstemp(3) or tmpfile(3) instead.

SEE ALSO

   mkstemp(3), mktemp(3), tempnam(3), tmpfile(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/.

                              2016-12-12                         TMPNAM(3)

---

More Linux Commands

---