file lock

9 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

Lock file creation

Hi, Please let me know how these steps are creating a lock file using echo " ". LOCK_FILE=${LOG_DIR}/${DBNAME}_MD.lock # create lock file if then echo "Another process is running already. Will terminate this one." >> ${LOG_FILE} 2>&1 echo "If the lock file is not needed, please...

2. Shell Programming and Scripting

Lock file creates with '?'

Hi, I am trying to create a lock file with the following code but for some reason after file is created it has wrong name "PASP?.lock??" Please let us know how to get rid of these '??' from file name and from where they are coming? #!/bin/ksh...

3. UNIX for Advanced & Expert Users

Testing privileges -lock lockfile /var/lock/subsys/..- Permission denied

Hi all, I have to test some user priviliges. The goal is to be sure that an unauthorized user can't restart some modules (ssh, mysql etc...). I'm trying to automate it with a shell script but in same cases I got the syslog broadcast message. Is there any way to simply get a return code...

4. Red Hat

Security Question: Lock after invalid login, Session Lock and Required Minimum Password Length

Hello all, If anyone has time, I have a few questions: How do I do the following in Linux. We are using Red Hat and Oracle Enterprise Linux, which is based on Red Hat too. 1. How to lock the account after a few (like 3) invalid password attempts? 2. How do you lock a screen after 30...

5. Red Hat

lock the file in linux

Hi, I want to lock the file in linux and the file cannot be edit or modify by other .I know in perl, there is function flock , but it is not worked. The file can be modifed and edit even if it is locked by flock . Any other way to lock the file and so other cannot edit or modifed it ???? Any...

6. UNIX for Dummies Questions & Answers

Lock File

Hi, We have a lock file being created called lck8c0001 created in Unixware 2.1.2. This is locking a printer. According to some websites, 8c0001 relates to the device name. How does one link 8c0001 to those devices listed in the /dev folder? I have done a ps -lp for all printers and have...

7. UNIX for Dummies Questions & Answers

how to lock keyboard without using lock command

how can I lock my keyboard while I'm away from the computer without using lock command. What other commands gives me the option to lock keyboard device? thanks

8. UNIX for Dummies Questions & Answers

lock file!

I found a lock file like this lrwxrwxr-x 1 sskb apollo 16 Oct 22 22:00 lock -> hostname:2747 (pl. note that hostname is a number like 123.4.5.6) but this was not shown in the file manager eventhough I had selected to show the hidden files. I could not even read the...

9. UNIX for Dummies Questions & Answers

How to lock a file in unix?

We wish to keep a sequence number in a file. When someone wants to get the next sequence number we need to lock the file, get the next number and increment it by one. How do you do that? I know how to get the number and increment it but how do I lock the file and test that it is locked or not...

LEARN ABOUT REDHAT

lockf

LOCKF(3)						     Linux Programmer's Manual							  LOCKF(3)

NAME

       lockf - apply, test or remove a POSIX lock on an open file

SYNOPSIS

       #include <sys/file.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 specified 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 appropriately.

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)

UNIX for Advanced & Expert Users