tmpnam(3)tmpnam(3)NAME
tmpnam, tempnam - Construct the name for a temporary file
SYNOPSIS
#include <stdio.h>
char *tmpnam(
char *s ); char *tempnam(
const char *directory,
const char *prefix );
LIBRARY
Standard C Library (libc)
STANDARDS
Interfaces documented on this reference page conform to industry stan‐
dards as follows:
tmpnam(), tempnam(): XSH4.2
Refer to the standards(5) reference page for more information about
industry standards and associated tags.
PARAMETERS
Specifies the address of an array of at least the number of bytes spec‐
ified by L_tmpnam, a constant defined in the stdio.h header file.
Points to the pathname of the directory in which the file is to be cre‐
ated. Points to an initial letter sequence with which the filename
begins. The prefix parameter can be null, or it can point to a string
of up to 5 bytes to be used as the beginning of the temporary filename.
DESCRIPTION
The tmpnam() and tempnam() functions generate filenames for temporary
files.
The tmpnam() function generates a filename using the pathname defined
as P_tmpdir in the stdio.h header file.
Files created using this function reside in a directory intended for
temporary use, and their names are unique. It is the application's
responsibility to use the unlink() function to remove the files when
they are no longer needed.
Between the time a filename is created and the file is opened, it is
possible for some other process to create a file with the same name.
This should not happen if that other process uses these functions or
the mktemp() function, and if the filenames are chosen to make duplica‐
tion by other means unlikely.
The tempnam() function allows you to control the choice of a directory.
If the directory parameter is null or points to a string that is not a
pathname for an appropriate directory, the pathname defined as P_tmpdir
in the stdio.h header file is used. If that pathname is not accessible,
/tmp is used. You can bypass the selection of a pathname by providing
an environment variable, TMPDIR, in the user's environment. The value
of the TMPDIR variable is a pathname for the desired temporary file
directory.
The prefix parameter can be used to specify a prefix of up to 5 bytes
for the temporary filename.
NOTES
If the s parameter is null, the tmpnam() function places its result
into an internal thread-specific buffer and returns a pointer to that
area. Subsequent calls to this function from the same thread overwrite
this buffer.
The tmpnam() function generates a different filename each time it is
called.
[Tru64 UNIX] If tmpnam() is called more than TMP_MAX times by a single
process, it starts recycling previously used names.
RETURN VALUES
If the s parameter is null, tmpnam() function places its result into an
internal thread-specific buffer and returns a pointer to that area.
If the s parameter is not null, it is assumed to be the address of an
array of at least the number of bytes specified by the L_tmpnam con‐
stant. The tmpnam() function places its results into that array and
returns the value of the s parameter.
Upon successful completion, the tempnam() function returns a pointer to
the generated pathname, suitable for use in a subsequent call to the
free() function. Otherwise, null is returned and errno is set to indi‐
cate the error.
ERRORS
If the tempnam() function fails, errno may be set to the following
value: Insufficient storage space is available.
SEE ALSO
Functions: fopen(3), free(3), malloc(3), mktemp(3), open(2), tmp‐
file(3), unlink(2)
Standards: standards(5)tmpnam(3)
