locking mechanism

Shell Programming and Scripting
1

I have a shell script.
How can use some kind of locking mechanism to ensure that the script is not being executed by two people
at the same time?

2

You can use setfacl command to set acl on the file that what user can run it.That what i think maby be some other have better idea

3 
#!/bin/ksh

lockit()
{
     [[ -w /tmp/lockfile ]] ||  > /tmp/lockfile
     let count=0
     echo 'checking lock...'
     while [[ -s /tmp/lockfile ]]
     do
           sleep 30           
           count=#(( count  + 1 ))
           if [[ count -eq 10 ]] ; then
                  echo 'cannot obtain lock'
                  exit 1
           fi
     done
      echo "$$" > /tmp/lockfile
     echo 'got lock'
}

unlock()
{
      > /tmp/lockfile

}
# main --------------------------
lockit

trap '> /tmp/lockfile; kill -9 $$ ' EXIT  HUP  INT

.  /path/to/myscript.sh
STATUS=$?

unlock
trap ' ' EXIT
exit $STATUS

Put your scriptname inside this type of script. If your script has trap commands they may override the ones here. This is just meant as a simple starting point.

4

That is really helpful

Thanks a lot