How do I make sure only one instance of a bash script runs?

How do I make sure only one instance of a bash script runs?

1. Introduction. In this tutorial, we’ll discuss different ways of ensuring only one instance of a bash script is running.
2. Using flock. We can use flock to create a lock on a file.
3. Using lockfile.
4. Writing the PID to a File.
5. Using a Directory.
6. Searching for the Process.
7. Conclusion.

Does Linux lock files?

File locking is a mechanism to restrict access to a file among multiple processes. This is because Linux usually doesn’t automatically lock open files. However, Linux supports two kinds of file locks: advisory locks and mandatory locks.

How do you lock a file in Linux?

Using gpg, you would do the following.

1. Open a terminal window.
2. Change to the ~/Documents directory with the command cd ~/Documents.
3. Encrypt the file with the command gpg -c important. docx.
4. Enter a unique password for the file and hit Enter.
5. Verify the newly typed password by typing it again and hitting Enter.

How to make sure only one instance of a bash?

A solution that does not require additional tools would be prefered. Almost like nsg’s answer: use a lock directory. Directory creation is atomic under linux and unix and *BSD and a lot of other OSes.

How to ensure only one instance of a given script is running?

Closed 3 years ago. What is the simplest/best way to ensure only one instance of a given script is running – assuming it’s Bash on Linux? it doesn’t let me run the same script from separate accounts – which I would like sometimes. Of course, I can write my own pidfile handling, but I sense that there should be a simple way to do it.

What’s the best way to exit a shell script?

For shell scripts, I tend to go with the mkdir over flock as it makes the locks more portable. Either way, using set -e isn’t enough. That only exits the script if any command fails. Your locks will still be left behind.

How to create a read only file descriptor in Bash?

This is a modified version of Anselmo’s Answer. The idea is to create a read only file descriptor using the bash script itself and use flock to handle the lock.