On Apache/1.3.41 (Unix) PHP/5.2.5 mod_perl/1.30 mod_gzip/1.3.26.1a
Under GNU General Public License
2009-01-09 09:21 @38.103.63.58 CrawledBy CCBot/1.0 (+http://www.commoncrawl.org/bot.html)
LOCKF(3) Linux Programmer’s Manual LOCKF(3)
NAME
lockf - apply, test or remove a POSIX lock on an open file
SYNOPSIS
#include <unistd.h>
int lockf(int fd, int cmd, off_t len);
DESCRIPTION
Apply, test or remove a POSIX lock on a section of an open file. The file is spec-
ified by fd, a file descriptor open for writing, the action by cmd, and the section
consists of byte positions pos..pos+len-1 if len is positive, and pos-len..pos-1 if
len is negative, where pos is the current file position, and if len is zero, the
section extends from the current file position to infinity, encompassing the
present and future end-of-file positions. In all cases, the section may extend
past current end-of-file.
On Linux, this call is just an interface for fcntl(2). (In general, the relation
between lockf and fcntl is unspecified.)
Valid operations are given below:
F_LOCK Set an exclusive lock on the specified section of the file. If (part of)
this section is already locked, the call blocks until the previous lock is
released. If this section overlaps an earlier locked section, both are
merged. File locks are released as soon as the process holding the locks
closes some file descriptor for the file. A child process does not inherit
these locks.
F_TLOCK
Same as F_LOCK but the call never blocks and returns an error instead if the
file is already locked.
F_ULOCK
Unlock the indicated section of the file. This may cause a locked section
to be split into two locked sections.
F_TEST Test the lock: return 0 if the specified section is unlocked or locked by
this process; return -1, set errno to EACCES, if another process holds a
lock.
RETURN VALUE
On success, zero is returned. On error, -1 is returned, and errno is set appropri-
ately.
ERRORS
EAGAIN The file is locked and F_TLOCK or F_TEST was specified, or the operation is
prohibited because the file has been memory-mapped by another process.
EBADF fd is not an open file descriptor.
EDEADLK
The command was T_LOCK and this lock operation would cause a deadlock.
EINVAL An invalid operation was specified in fd.
ENOLCK Too many segment locks open, lock table is full.
CONFORMING TO
SYSV, POSIX 1003.1-2001
SEE ALSO
fcntl(2), flock(2)
There are also locks.txt and mandatory.txt in /usr/src/linux/Documentation.
Linux 2.0 2002-04-22 LOCKF(3)
Generated by $Id: phpMan.php,v 4.55 2007/09/05 04:42:51 chedong Exp $ Author: Che Dong
On Apache/1.3.41 (Unix) PHP/5.2.5 mod_perl/1.30 mod_gzip/1.3.26.1a
Under GNU General Public License
2009-01-09 09:21 @38.103.63.58 CrawledBy CCBot/1.0 (+http://www.commoncrawl.org/bot.html)