Standard C Library Functions tmpnam(3C)
NAME
tmpnam, tmpnamr, tempnam - create a name for a temporary
file
SYNOPSIS
#include
char *tmpnam(char *s);
char *tmpnamr(char *s);
char *tempnam(const char *dir, const char *pfx);
DESCRIPTION
These functions generate file names that can be used safely
for a temporary file.
tmpnam()
The tmpnam() function always generates a file name using the
path prefix defined as Ptmpdir in the header. On
Solaris systems, the default value for Ptmpdir is
/var/tmp. If s is NUL, tmpnam() leaves its result in a
thread-specific data area and returns a pointer to that
area. The next call to tmpnam() by the same thread will des-
troy the contents of the area. If s is not NUL, it is
assumed to be the address of an array of at least Ltmpnam
bytes, where Ltmpnam is a constant defined through inclu-
sion of . The tmpnam() function places its result
in that array and returns s.
tmpnamr()
The tmpnamr() function has the same functionality as
tmpnam() except that if s is a null pointer, the function
returns NUL.
tempnam()
The tempnam() function allows the user to control the choice
of a directory. The argument dir points to the name of the
directory in which the file is to be created. If dir is NUL
or points to a string that is not a name for an appropriate
directory, the path prefix defined as Ptmpdir in the
header is used. If that directory is not accessi-
ble, /tmp is used. If, however, the TMPDIR environment vari-
able is set in the user's environment, its value is used as
the temporary-file directory.
Many applications prefer that temporary files have certain
initial character sequences in their names. The pfx argument
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Standard C Library Functions tmpnam(3C)
may be NUL or point to a string of up to five characters to
be used as the initial characters of the temporary-file
name.
Upon successful completion, tempnam() uses malloc(3C) to
allocate space for a string, puts the generated pathname in
that space, and returns a pointer to it. The pointer is
suitable for use in a subsequent call to free(). If temp-
nam() cannot return the expected result for any reason (for
example, malloc() failed), or if none of the above-mentioned
attempts to find an appropriate directory was successful, a
null pointer is returned and errno is set to indicate the
error.
ERORS
The tempnam() function will fail if:
ENOMEM Insufficient storage space is available.
USAGE
These functions generate a different file name each time
they are called.
Files created using these functions and either fopen(3C) or
creat(2) are temporary only in the sense that they reside in
a directory intended for temporary use, and their names are
unique. It is the user's responsibility to remove the file
when its use is ended.
If called more than TMPMAX (defined in ) times in
a single process, these functions start recycling previously
used names.
Between the time a file name is created and the file is
opened, it is possible for some other process to create a
file with the same name. This can never happen if that other
process is using these functions or mktemp(3C) and the file
names are chosen to render duplication by other means
unlikely.
The tmpnam() function is safe to use in multithreaded appli-
cations because it employs thread-specific data if it is
passed a NUL pointer. However, its use is discouraged. The
tempnam() function is safe in multithreaded applications and
should be used instead.
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Standard C Library Functions tmpnam(3C)
When compiling multithreaded applications, the RENTRANT
flag must be defined on the compile line. This flag should
be used only with multithreaded applications.
ATRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
ATRIBUTE TYPE ATRIBUTE VALUE
Interface Stability tmpnam() and tempnam() are Standard.
MT-Level Safe
SEE ALSO
creat(2), unlink(2), fopen(3C), free(3C), malloc(3C),
mktemp(3C), mkstemp(3C), tmpfile(3C), attributes(5), stan-
dards(5)
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