mkstemp(3) - Linux manual page (original) (raw)
mkstemp(3) Library Functions Manual mkstemp(3)
NAME top
mkstemp, mkostemp, mkstemps, mkostemps - create a unique temporary
fileLIBRARY top
Standard C library (_libc_, _-lc_)SYNOPSIS top
**#include <stdlib.h>**
**int mkstemp(char ***_template_**);**
**int mkostemp(char ***_template_**, int** _flags_**);**
**int mkstemps(char ***_template_**, int** _suffixlen_**);**
**int mkostemps(char ***_template_**, int** _suffixlen_**, int** _flags_**);**Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
**mkstemp**():
_XOPEN_SOURCE >= 500
|| /* glibc >= 2.12: */ _POSIX_C_SOURCE >= 200809L
|| /* glibc <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE
**mkostemp**():
_GNU_SOURCE
**mkstemps**():
/* glibc >= 2.19: */ _DEFAULT_SOURCE
|| /* glibc <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE
**mkostemps**():
_GNU_SOURCEDESCRIPTION top
The **mkstemp**() function generates a unique temporary filename from
_template_, creates and opens the file, and returns an open file
descriptor for the file.
The last six characters of _template_ must be "XXXXXX" and these are
replaced with a string that makes the filename unique. Since it
will be modified, _template_ must not be a string constant, but
should be declared as a character array.
The file is created with permissions 0600, that is, read plus
write for owner only. The returned file descriptor provides both
read and write access to the file. The file is opened with the
[open(2)](../man2/open.2.html) **O_EXCL** flag, guaranteeing that the caller is the process
that creates the file.
The **mkostemp**() function is like **mkstemp**(), with the difference
that the following bits—with the same meaning as for [open(2)](../man2/open.2.html)—may
be specified in _flags_: **O_APPEND**, **O_CLOEXEC**, and **O_SYNC**. Note that
when creating the file, **mkostemp**() includes the values **O_RDWR**,
**O_CREAT**, and **O_EXCL** in the _flags_ argument given to [open(2)](../man2/open.2.html);
including these values in the _flags_ argument given to **mkostemp**()
is unnecessary, and produces errors on some systems.
The **mkstemps**() function is like **mkstemp**(), except that the string
in _template_ contains a suffix of _suffixlen_ characters. Thus,
_template_ is of the form _prefixXXXXXXsuffix_, and the string XXXXXX
is modified as for **mkstemp**().
The **mkostemps**() function is to **mkstemps**() as **mkostemp**() is to
**mkstemp**().RETURN VALUE top
On success, these functions return the file descriptor of the
temporary file. On error, -1 is returned, and _[errno](../man3/errno.3.html)_ is set to
indicate the error.ERRORS top
**EEXIST** Could not create a unique temporary filename. Now the
contents of _template_ are undefined.
**EINVAL** For **mkstemp**() and **mkostemp**(): The last six characters of
_template_ were not XXXXXX; now _template_ is unchanged.
For **mkstemps**() and **mkostemps**(): _template_ is less than _(6 +_
_suffixlen)_ characters long, or the last 6 characters before
the suffix in _template_ were not XXXXXX.
These functions may also fail with any of the errors described for
[open(2)](../man2/open.2.html).ATTRIBUTES top
For an explanation of the terms used in this section, see
[attributes(7)](../man7/attributes.7.html).
┌──────────────────────────────────────┬───────────────┬─────────┐
│ **Interface** │ **Attribute** │ **Value** │
├──────────────────────────────────────┼───────────────┼─────────┤
│ **mkstemp**(), **mkostemp**(), **mkstemps**(), │ Thread safety │ MT-Safe │
│ **mkostemps**() │ │ │
└──────────────────────────────────────┴───────────────┴─────────┘STANDARDS top
**mkstemp**()
POSIX.1-2001.
**mkstemps**()
BSD.
**mkostemp**()
**mkostemps**()
GNU.HISTORY top
**mkstemp**()
4.3BSD, POSIX.1-2001.
**mkstemps**()
glibc 2.11. BSD, Mac OS X, Solaris, Tru64.
**mkostemp**()
glibc 2.7.
**mkostemps**()
glibc 2.11.
In glibc versions 2.06 and earlier, the file is created with
permissions 0666, that is, read and write for all users. This old
behavior may be a security risk, especially since other UNIX
flavors use 0600, and somebody might overlook this detail when
porting programs. POSIX.1-2008 adds a requirement that the file
be created with mode 0600.
More generally, the POSIX specification of **mkstemp**() does not say
anything about file modes, so the application should make sure its
file mode creation mask (see [umask(2)](../man2/umask.2.html)) is set appropriately before
calling **mkstemp**() (and **mkostemp**()).SEE ALSO top
[mkdtemp(3)](../man3/mkdtemp.3.html), [mktemp(3)](../man3/mktemp.3.html), [tempnam(3)](../man3/tempnam.3.html), [tmpfile(3)](../man3/tmpfile.3.html), [tmpnam(3)](../man3/tmpnam.3.html)COLOPHON top
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man-pages@man7.orgLinux man-pages 6.10 2024-07-23 mkstemp(3)
Pages that refer to this page:mktemp(1), getpid(2), mkdtemp(3), mktemp(3), pmprintf(3), tempnam(3), tmpfile(3), tmpnam(3), file-hierarchy(7)