.\" Copyright (c) 1999 Andries Brouwer (aeb@cwi.nl)
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.TH TEMPNAM 3  "14 June 1999" "" "Linux Programmer's Manual"
.SH NAME
tempnam \- create a name for a temporary file
.SH SYNOPSIS
.nf
.B #include <stdio.h>
.sp
.BI "char *tempnam(const char *" dir ", const char *" pfx );
.fi
.SH DESCRIPTION
The
.B tempnam()
function returns a pointer to a string that is a valid filename,
and such that a file with this name did not exist when
.B tempnam()
checked.
The filename suffix of the pathname generated will start with
.I pfx
in case
.I pfx
is a non-NULL string of at most five bytes.
The directory prefix part of the pathname generated is required to
be `appropriate' (often that at least implies writable).
Attempts to find an appropriate directory go through the following
steps: (i) In case the environment variable TMPDIR exists and
contains the name of an appropriate directory, that is used.
(ii) Otherwise, if the
.I dir
argument is non-NULL and appropriate, it is used.
(iii) Otherwise, P_tmpdir (as defined in
.IR <stdio.h> )
is used when appropriate.
(iv) Finally an implementation-defined directory may be used.
.SH "RETURN VALUE"
The
.B tempnam()
function returns a pointer to a unique temporary 
filename, or NULL if a unique name cannot be generated.
.SH ERRORS
.TP
.B ENOMEM
Allocation of storage failed.
.LP
.SH NOTES
SUSv2 does not mention the use of TMPDIR; glibc will use it only
when the program is not suid.
SVID2 specifies that the directory used under (iv) is
.IR /tmp .
SVID2 specifies that the string returned by
.B tempnam()
was allocated using
.BR malloc (3)
and hence can be freed by
.BR free (3).
.LP
The
.B tempnam()
function generates a different string each time it is called,
up to TMP_MAX (defined in
.IR <stdio.h> )
times. If it is called more than TMP_MAX times,
the behaviour is implementation defined.
.LP
In case the
.I pfx
argument has length larger than five, glibc will use the first
five bytes.
Upon failure to find a unique name, glibc will return EEXIST.
.SH BUGS
The precise meaning of `appropriate' is undefined;
it is unspecified how accessibility of a directory is determined.
Never use this function. Use
.BR mkstemp (3)
instead.
.SH "CONFORMING TO"
SVID 2, BSD 4.3
.SH "SEE ALSO"
.BR mktemp (3),
.BR mkstemp (3),
.BR tmpfile (3),
.BR tmpnam (3)