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MKDTEMP(3P) POSIX Programmer's Manual MKDTEMP(3P)
This manual page is part of the POSIX Programmer's Manual. The Linux
implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior), or
the interface may not be implemented on Linux.
mkdtemp, mkstemp — create a unique directory or file
#include <stdlib.h>
char *mkdtemp(char *template);
int mkstemp(char *template);
The mkdtemp() function uses the contents of template to construct a
unique directory name. The string provided in template shall be a
pathname ending with six trailing 'X's. The mkdtemp() function shall
replace each 'X' with a character from the portable filename
character set. The characters are chosen such that the resulting name
does not duplicate the name of an existing file at the time of a call
to mkdtemp(). The unique directory name is used to attempt to create
the directory using mode 0700 as modified by the file creation mask.
The mkstemp() function shall replace the contents of the string
pointed to by template by a unique pathname, and return a file
descriptor for the file open for reading and writing. The mkstemp()
function shall create the file, and obtain a file descriptor for it,
as if by a call to:
open(pathname, O_RDWR|O_CREAT|O_EXCL, S_IRUSR|S_IWUSR)
The function thus prevents any possible race condition between
testing whether the file exists and opening it for use. The string in
template should look like a pathname with six trailing 'X's;
mkstemp() replaces each 'X' with a character from the portable
filename character set. The characters are chosen such that the
resulting name does not duplicate the name of an existing file at the
time of a call to mkstemp().
Upon successful completion, the mkdtemp() function shall return a
pointer to the string containing the directory name if it was
created. Otherwise, it shall return a null pointer and shall set
errno to indicate the error.
Upon successful completion, the mkstemp() function shall return an
open file descriptor. Otherwise, it shall return −1 if no suitable
file could be created.
The mkdtemp() function shall fail if:
EACCES Search permission is denied on a component of the path prefix,
or write permission is denied on the parent directory of the
directory to be created.
EINVAL The string pointed to by template does not end in "XXXXXX".
ELOOP A loop exists in symbolic links encountered during resolution
of the path of the directory to be created.
EMLINK The link count of the parent directory would exceed
{LINK_MAX}.
ENAMETOOLONG
The length of a component of a pathname is longer than
{NAME_MAX}.
ENOENT A component of the path prefix specified by the template
argument does not name an existing directory.
ENOSPC The file system does not contain enough space to hold the
contents of the new directory or to extend the parent
directory of the new directory.
ENOTDIR
A component of the path prefix names an existing file that is
neither a directory nor a symbolic link to a directory.
EROFS The parent directory resides on a read-only file system.
The mkdtemp() function may fail if:
ELOOP More than {SYMLOOP_MAX} symbolic links were encountered during
resolution of the path of the directory to be created.
ENAMETOOLONG
The length of a pathname exceeds {PATH_MAX}, or pathname
resolution of a symbolic link produced an intermediate result
with a length that exceeds {PATH_MAX}.
The error conditions for the mkstemp() function are defined in
open(3p).
The following sections are informative.
Generating a Pathname
The following example creates a file with a 10-character name
beginning with the characters "file" and opens the file for reading
and writing. The value returned as the value of fd is a file
descriptor that identifies the file.
#include <stdlib.h>
...
char template[] = "/tmp/fileXXXXXX";
int fd;
fd = mkstemp(template);
It is possible to run out of letters.
The mkdtemp() and mkstemp() functions need not check to determine
whether the filename part of template exceeds the maximum allowable
filename length.
None.
None.
getpid(3p), mkdir(3p), open(3p), tmpfile(3p), tmpnam(3p)
The Base Definitions volume of POSIX.1‐2008, stdlib.h(0p)
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The Open
Group Base Specifications Issue 7, Copyright (C) 2013 by the
Institute of Electrical and Electronics Engineers, Inc and The Open
Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
applied.) In the event of any discrepancy between this version and
the original IEEE and The Open Group Standard, the original IEEE and
The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.unix.org/online.html .
Any typographical or formatting errors that appear in this page are
most likely to have been introduced during the conversion of the
source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 MKDTEMP(3P)
Pages that refer to this page: stdlib.h(0p), getpid(3p), mkdir(3p), mkstemp(3p), open(3p), tempnam(3p), tmpfile(3p), tmpnam(3p)