How to secure only one running instance of Linux script?

[Bamsefar]

Hi,

So I am trying to get one of my scripts in pfSense to only start once so to speak, just as a precaution. Normal mode would be it starts itself automatic, and well that's just enough. However I like to double check that it is not already running. So I though I code it like:

running=$(ps aux | grep CheckIfHome.sh | grep -v grep | grep -o CheckIfHome.sh | wc -l);

if [ $running > 1 ];
then
  exit
fi

But this will fail with "invalid variable" and for some reason my head seems to be on vacation…? Anyone that might help out?

[Gertjan]

Hi,

No need for anyone. Just one will and you'll be fine.
What about this one : shell script run one instance  ;)

[Bamsefar]

I ended up with something like this:

if [ `pgrep script.sh | wc -l` -gt 1 ];
then
  exit
fi