Section (3) tmpnam
tmpnam, tmpnam_r — create a name for a temporary file
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
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
The created pathname has a directory prefix
P_tmpdir are defined in
just like the
performs the same task as
tmpnam(), but returns NULL (to indicate an
These functions return a pointer to a unique temporary filename, or NULL if a unique name cannot be generated.
For an explanation of the terms used in this section, see attributes(7).
||Thread safety||MT-Unsafe race:tmpnam/!s|
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.
generates a different string each time it is called, up to
TMP_MAX times. If it is called
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
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Copyright (c) 1999 Andries Brouwer (aebcwi.nl)
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2003-11-15, aeb, added tmpnam_r