NAME
tmpnam, tmpnamr - create a name for a temporary file SYNOPSIS
#include
char *tmpnam(char *s); DESCRIPTION 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 pathname that is created, has a directory prefix Ptmpdir. (Both Ltmpnam and Ptmpdir are defined in , just like the TMPMAX mentioned below.) RETURN VALUE The tmpnam() function returns 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 │ ├───────────┼───────────────┼──────────────────────────┤
│tmpnamr() │ Thread safety │ MT-Safe │ └───────────┴───────────────┴──────────────────────────┘ CONFORMING TO
SVr4, 4.3BSD, C89, C99, POSIX.1-2001. POSIX.1-2008 marks tmpnam() as obsolete. NOTES The tmpnam() function generates a different string each time it is called, up to TMPMAX times. If it is called more than TMPMAX times, the behavior is implementation defined. Although tmpnam() generates names that are difficult to guess, it is nevertheless possible that between the time that tmpnam() returns a pathname, 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) OEXCL 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 POSIXTHREADS or POSIXTHREADSAFEFUNCTIONS is defined. A POSIX draft proposed to use a function tmpnamr() defined by char * tmpnamr(char *s) { return s ? tmpnam(s) : NULL; } apparently as a warning not to use NULL. A few systems implement it. To get a glibc prototype for this function from
, define SVIDSOURCE or BSDSOURCE (before including any header file). BUGS Never use this function. Use mkstemp(3) or tmpfile(3) instead. SEE ALSO mkstemp(3), mktemp(3), tempnam(3), tmpfile(3) COLOPHON This page is part of release 3.53 of the Linux man-pages project. A description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
2013-06-21 TMPNAM(3)