The OP is after a portable solution, so lets test for executable /usr/bin/flock
and use that when available but revert to the mkdir method on systems without it:
These 2 Users Gave Thanks to Chubler_XL For This Post:
Hi,
I am writing a shell script to invoke a C++ program. Before I start the C++ program (oi7loadbalancer), I am checking if the process is already running. I start the process only if it is not already running. I have the following check in my script.
proccount=`ps -f -u $USER_NAME | grep... (8 Replies)
Alright, I think I know what I am doing with sed(which probably means I don't). But I cant figure out how to replace just the first occurance of a string. I have tried sed, ed, and grep but can't seem to figure it out. If you have any suggestions I am open to anything! (3 Replies)
Hi,
PHP user here. I'm using an endless loop to perform to mimic a cron. The script does something every 20 minutes. It sleep()s in the meantime.
I have various checks that ensure that only instance can run, including a "gentleman agreement" locked file.
However, I'd like to make sure... (2 Replies)
Hello.
I have a status command in AIX box, which provides output as below:
$ status
You are running the application on pegasus2
----Program Name------|--Avail / Total---------|
MQ | 1/2 |
ORACLE | 10/10 |
TMADMIN ... (3 Replies)
Hi All,
After reading that the sort command in Linux can be made to use many processor cores just by using a simple script which I found on the internet, I was wondering if I can use similar techniques for programs like the awk and sed?
#!/bin/bash
# Usage: psort filename <chunksize>... (7 Replies)
I have run 10 instances of the process eg, process name is BG
nohup /WP01IRB1_irbapp/IRBWPROD/RB/bin/BG -c 1 -t 23 -a '-caTop TESTBILLCYCLE='5FEB13_81PT19NPT''>a.txt &
nohup /WP01IRB1_irbapp/IRBWPROD/RB/bin/BG -c 2 -t 23 -a '-caTop TESTBILLCYCLE='5FEB13_81PT19NPT''>b.txt &
nohup... (3 Replies)
Hi,
I want to write one program in C in Unix OS which will check the running status of a process time to time. If the process is stopped somehow by any means, it will ensure that the process is restarted and only one copy of the process image should run in memory at any point of time for the user.... (2 Replies)
Hello All,
Greetings !!
I have a query here to all is as follows:
Question: Let's say we are running a script in a UNIX box and we have opened an another session and then made changes in script of some statements NOT to be print some values(just an example) so when I am monitoring the... (5 Replies)
Hi Guys,
I have a main_script.sh which runs every day and scheduled in crontab.
in the main script i read data from config file
test.config
apple
mango
orange
main_script.sh
for i in `cat test.config`
do
if
then
echo 'Apple' (3 Replies)
Discussion started by: Master_Mind
3 Replies
LEARN ABOUT SUSE
flock
FLOCK(1) H. Peter Anvin FLOCK(1)NAME
flock - Manage locks from shell scripts
SYNOPSIS
flock [-sxon] [-w timeout] lockfile [-c] command...
flock [-sxon] [-w timeout] lockdir [-c] command...
flock [-sxun] [-w timeout] fd
DESCRIPTION
This utility manages flock(2) locks from within shell scripts or the command line.
The first and second forms wraps the lock around the executing a command, in a manner similar to su(1) or newgrp(1). It locks a specified
file or directory, which is created (assuming appropriate permissions), if it does not already exist.
The third form is convenient inside shell scripts, and is usually used the following manner:
(
flock -s 200
# ... commands executed under lock ...
) 200>/var/lock/mylockfile
The mode used to open the file doesn't matter to flock; using > or >> allows the lockfile to be created if it does not already exist, how-
ever, write permission is required; using < requires that the file already exists but only read permission is required.
By default, if the lock cannot be immediately acquired, flock waits until the lock is available.
OPTIONS -s, --shared
Obtain a shared lock, sometimes called a read lock.
-x, -e, --exclusive
Obtain an exclusive lock, sometimes called a write lock. This is the default.
-u, --unlock
Drop a lock. This is usually not required, since a lock is automatically dropped when the file is closed. However, it may be
required in special cases, for example if the enclosed command group may have forked a background process which should not be hold-
ing the lock.
-n, --nb, --nonblock
Fail (with an exit code of 1) rather than wait if the lock cannot be immediately acquired.
-w, --wait, --timeout seconds
Fail (with an exit code of 1) if the lock cannot be acquired within seconds seconds. Decimal fractional values are allowed.
-o, --close
Close the file descriptor on which the lock is held before executing command. This is useful if command spawns a child process
which should not be hold ing the lock.
-c, --command command
Pass a single command to the shell with -c.
-h, --help
Print a help message.
AUTHOR
Written by H. Peter Anvin <hpa@zytor.com>.
COPYRIGHT
Copyright (C) 2003-2006 H. Peter Anvin.
This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICU-
LAR PURPOSE.
SEE ALSO flock(2)AVAILABILITY
The flock command is part of the util-linux-ng package and is available from ftp://ftp.kernel.org/pub/linux/utils/util-linux-ng/.
flock utility 4 Feb 2006 FLOCK(1)