tmpnam(3) - Linux manual page (original) (raw)

tmpnam(3) Library Functions Manual tmpnam(3)

NAME top

   tmpnam, tmpnam_r - create a name for a temporary file

LIBRARY top

   Standard C library (_libc_, _-lc_)

SYNOPSIS top

   **#include <stdio.h>**

   **[[deprecated]] char *tmpnam(char ***_s_**);**
   **[[deprecated]] 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 top

   **Note:** avoid using these functions; use [mkstemp(3)](../man3/mkstemp.3.html) or [tmpfile(3)](../man3/tmpfile.3.html)
   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
   _Ltmpnam_) pointed to by _s_ and the value _s_ is returned in case of
   success.

   The created pathname has a directory prefix _Ptmpdir_.  (Both
   _Ltmpnam_ and _Ptmpdir_ 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 top

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

ERRORS top

   No errors are defined.

ATTRIBUTES top

   For an explanation of the terms used in this section, see
   [attributes(7)](../man7/attributes.7.html).
   ┌─────────────────────┬───────────────┬──────────────────────────┐
   │ **Interface** │ **Attribute** │ **Value** │
   ├─────────────────────┼───────────────┼──────────────────────────┤
   │ **tmpnam**()            │ Thread safety │ MT-Unsafe race:tmpnam/!s │
   ├─────────────────────┼───────────────┼──────────────────────────┤
   │ **tmpnam_r**()          │ Thread safety │ MT-Safe                  │
   └─────────────────────┴───────────────┴──────────────────────────┘

STANDARDS top

   **tmpnam**()
          C11, POSIX.1-2008.

   **tmpnam_r**()
          None.

HISTORY top

   **tmpnam**()
          SVr4, 4.3BSD, C89, POSIX.1-2001.  Obsolete in POSIX.1-2008.

   **tmpnam_r**()
          Solaris.

NOTES top

   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)](../man2/open.2.html), or
   create it as a symbolic link.  This can lead to security holes.
   To avoid such possibilities, use the [open(2)](../man2/open.2.html) **O_EXCL** flag to open
   the pathname.  Or better yet, use [mkstemp(3)](../man3/mkstemp.3.html) or [tmpfile(3)](../man3/tmpfile.3.html).

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

BUGS top

   Never use these functions.  Use [mkstemp(3)](../man3/mkstemp.3.html) or [tmpfile(3)](../man3/tmpfile.3.html) instead.

SEE ALSO top

   [mkstemp(3)](../man3/mkstemp.3.html), [mktemp(3)](../man3/mktemp.3.html), [tempnam(3)](../man3/tempnam.3.html), [tmpfile(3)](../man3/tmpfile.3.html)

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Linux man-pages 6.10 2024-07-23 tmpnam(3)

Pages that refer to this page:getpid(2), mkdtemp(3), mkstemp(3), mktemp(3), stdio(3), tempnam(3), tmpfile(3)