Instead of telling us how you want to do it, like find a pid, how about file existence?
I do not see why an approach like this will not work. It does have issues if your script fails a lot or if you reboot during the time the script is running. But. You can easily add an ignore option, myscript.sh -I, so that it runs regardless of the exitence of the file.
Thank you for your input. This is what I think I'm going to do. I can't get the counter to work right, but I'll keep messing with it.
#!/bin/sh
EMAIL1="djoy3@nomail.com"
count=0
until ls myscript2.sh.trg >>/dev/null 2>&1
do
count=count+1
if [ count -gt 16 ]
then
echo "Max wait time exceeded for myscript2.sh job" | mailx -s "myscript2.sh job error - `date`" ${EMAIL1}
exit 1
fi
sleep 20
done
#do other processing here
echo "Other processing running"
touch myscript2.sh.trg
I would like to allow only one instance of a script to run at any moment.
I've tried the following solution to count the instances but the result is always the number of running instances plus one and I can't find the problem
ps -ef | grep $0 | sed '/^$/ d' | sed '/grep/ d' | wc -l
Please... (2 Replies)
Hello all,
I currently connect to several servers multiple times a day. Most of the time I connect via SSH through the terminal emulator poderosa (my personal favorite), but sometimes I connect via telnet through xstart because I need it to export a GUI.
What I want to do is add something to... (3 Replies)
Hi all,
I encountered a problem where my script stops running the remaining checks after becoming an admin that is written within the script.
For example:
=========================================
#!/bin/sh
check 1 # Runs successfully
check 2 # Runs successfully
/com/bin/admin #... (1 Reply)
Hi All,
I have a requirement to perform the following checks.
Input file is a "|" delimited file and looks like this.
A|c1|c2|c3|....
B|G1|G2|G3....
C|H1|H2|H3...
A|c4|c5|c6|....
B|G4|G5|G6....
C|H4|H5|H6...
Now the check is to see if all the "A" records have a corresponding B... (7 Replies)
Hi.
I'm triyng to make a Bash Script that checks (recursively) the MD5 from all the files in a certain directory and compare them against some other check that should be already done and saved in a file.
I've reached to the point where i have the MD5 from the file and the MD5 that the script... (1 Reply)
Hello to all @here,
as Iīm new to this forum, I will try to start in a easy way for my first post. Iīm not beginner in scripting, but also not a proffessional. So please keep easy, if I donīt understand your explanation at once ;) I donīt mean it in a bad way!
Here is the Problem:
There were... (2 Replies)
I'm likely going to explain this clumsily, so apologies in advance:
I have the following script:
#!/bin/bash
pidPrefix="logGen"
checkPrime ()
{
if /sbin/ifconfig eth0:0|/bin/grep -wq inet;then isPrime=1;else isPrime=0;fi
}
killScript ()
{
/usr/bin/find /var/run -name... (4 Replies)
Hi ,
I need a script which performs below activity
I have one file named "testfile" in 9 different directories with same name.
I want to perform below action with each testfile of each directory.
if ; then
mv listfiles listfiles_`date +%b%y`
else
echo No Such files
fi
... (4 Replies)
Hi ,
I need a script for processing below scenario.
I have to check daily by doing ftp IP to check it is logging or not.
So i want this activity to be automated such that if login succesful i will get "FTP LOGIN SUCCESS" in a log file and if fails i want the error message in the same log... (1 Reply)
Hi All,
I have a cron job set up which is set to run every 10 seconds.
What I need to do is have the script do a check to see if it is already running such that if it is running it wont fire up additional instances and processes according to its normal process.
For example if I have a script... (4 Replies)
Discussion started by: landossa
4 Replies
LEARN ABOUT MINIX
flock
FLOCK(1) User Commands FLOCK(1)NAME
flock - manage locks from shell scripts
SYNOPSIS
flock [options] file|directory command [arguments]
flock [options] file|directory -c command
flock [options] number
DESCRIPTION
This utility manages flock(2) locks from within shell scripts or from the command line.
The first and second of the above forms wrap the lock around the execution of a command, in a manner similar to su(1) or newgrp(1). They
lock a specified file or directory, which is created (assuming appropriate permissions) if it does not already exist. By default, if the
lock cannot be immediately acquired, flock waits until the lock is available.
The third form uses an open file by its file descriptor number. See the examples below for how that can be used.
OPTIONS -c, --command command
Pass a single command, without arguments, to the shell with -c.
-E, --conflict-exit-code number
The exit code used when the -n option is in use, and the conflicting lock exists, or the -w option is in use, and the timeout is
reached. The default value is 1.
-F, --no-fork
Do not fork before executing command. Upon execution the flock process is replaced by command which continues to hold the lock.
This option is incompatible with --close as there would otherwise be nothing left to hold the lock.
-e, -x, --exclusive
Obtain an exclusive lock, sometimes called a write lock. This is the default.
-n, --nb, --nonblock
Fail rather than wait if the lock cannot be immediately acquired. See the -E option for the exit code used.
-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 holding the lock.
-s, --shared
Obtain a shared lock, sometimes called a read lock.
-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.
-w, --wait, --timeout seconds
Fail if the lock cannot be acquired within seconds. Decimal fractional values are allowed. See the -E option for the exit code
used. The zero number of seconds is interpreted as --nonblock.
--verbose
Report how long it took to acquire the lock, or why the lock could not be obtained.
-V, --version
Display version information and exit.
-h, --help
Display help text and exit.
EXAMPLES
shell1> flock /tmp -c cat
shell2> flock -w .007 /tmp -c echo; /bin/echo $?
Set exclusive lock to directory /tmp and the second command will fail.
shell1> flock -s /tmp -c cat
shell2> flock -s -w .007 /tmp -c echo; /bin/echo $?
Set shared lock to directory /tmp and the second command will not fail. Notice that attempting to get exclusive lock with second
command would fail.
shell> flock -x local-lock-file echo 'a b c'
Grab the exclusive lock "local-lock-file" before running echo with 'a b c'.
(
flock -n 9 || exit 1
# ... commands executed under lock ...
) 9>/var/lock/mylockfile
The form is convenient inside shell scripts. The mode used to open the file doesn't matter to flock; using > or >> allows the lock-
file to be created if it does not already exist, however, write permission is required. Using < requires that the file already
exists but only read permission is required.
[ "${FLOCKER}" != "$0" ] && exec env FLOCKER="$0" flock -en "$0" "$0" "$@" || :
This is useful boilerplate code for shell scripts. Put it at the top of the shell script you want to lock and it'll automatically
lock itself on the first run. If the env var $FLOCKER is not set to the shell script that is being run, then execute flock and grab
an exclusive non-blocking lock (using the script itself as the lock file) before re-execing itself with the right arguments. It
also sets the FLOCKER env var to the right value so it doesn't run again.
EXIT STATUS
The command uses sysexits.h return values for everything, except when using either of the options -n or -w which report a failure to
acquire the lock with a return value given by the -E option, or 1 by default.
When using the command variant, and executing the child worked, then the exit status is that of the child command.
AUTHOR
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 package and is available from Linux Kernel Archive <https://www.kernel.org/pub/linux/utils
/util-linux/>.
util-linux July 2014 FLOCK(1)