NAME
mkstemp, mkostemp, mkstemps, mkostemps - create a unique temporary file SYNOPSIS
#include
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 featuretestmacros(7)): mkstemp(): BSDSOURCE || SVIDSOURCE || XOPENSOURCE >= 500 || XOPENSOURCE && XOPENSOURCEEXTENDED || /* Since glibc 2.12: */ POSIXCSOURCE >= 200112L mkostemp(): GNUSOURCE mkstemps(): BSDSOURCE || SVIDSOURCE mkostemps(): GNUSOURCE DESCRIPTION The mkstemp() function generates a unique temporary filename from tem‐ plate, 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) OEXCL flag, guaranteeing that the caller is the process that creates the file. The mkostemp() function is like mkstemp(), with the difference that flags as for open(2) may be specified in flags (e.g., OAPPEND, OSYNC). 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 On success, these functions return the file descriptor of the temporary file. On error, -1 is returned, and errno is set appropriately. ERRORS 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 tem‐ plate were not XXXXXX; now template is unchanged. For mkstemps() and mkostemps(): template is less than (6 + suf‐ fixlen) 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). VERSIONS mkostemp() is available since glibc 2.7. mkstemps() and mkostemps() are available since glibc 2.11. ATTRIBUTES For an explanation of the terms used in this section, see attributes(7). ┌────────────────────────┬───────────────┬─────────┐ │Interface │ Attribute │ Value │ ├────────────────────────┼───────────────┼─────────┤
│mkstemp(), mkostemp(), │ Thread safety │ MT-Safe │ │mkstemps(), mkostemps() │ │ │ └────────────────────────┴───────────────┴─────────┘ CONFORMING TO
mkstemp(): 4.3BSD, POSIX.1-2001. mkstemps(): unstandardized, but appears on several other systems. mkostemp() and mkostemps(): are glibc extensions. NOTES In glibc versions 2.06 and earlier, the file is created with permis‐ sions 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 any‐ thing about file modes, so the application should make sure its file mode creation mask (see umask(2)) is set appropriately before calling mkstemp() (and mkostemp()). The prototype for mktemp() is in
for libc4, libc5, glibc1; glibc2 follows POSIX.1 and has the prototype in . SEE ALSO mkdtemp(3), mktemp(3), tempnam(3), tmpfile(3), tmpnam(3) COLOPHON This page is part of release 3.53 of the Linux man-pages project. A description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
GNU 2012-12-21 MKSTEMP(3)