trap for cleanup on exit in Bash Scripting

Introduction

Use trap to run cleanup code automatically when your script ends or is interrupted. This helps keep things tidy and safe.

You want to delete temporary files when your script finishes or stops.

You need to close network connections or release resources before exiting.

You want to show a goodbye message or log info when the script ends.

You want to handle user pressing Ctrl+C to stop the script safely.

Syntax

Bash Scripting

trap 'commands_to_run' signals

commands_to_run is the code you want to execute on exit or signal.

signals are events like EXIT (script ends) or INT (Ctrl+C).

Examples

Runs 'echo Cleanup done' when the script finishes normally or by exit.

Bash Scripting

trap 'echo Cleanup done' EXIT

Deletes a temporary file when the script ends.

Bash Scripting

trap 'rm -f /tmp/tempfile' EXIT

Prints a message and exits when you press Ctrl+C.

Bash Scripting

trap 'echo Interrupted; exit' INT

Sample Program

This script creates a temp file, sets a trap to delete it when the script ends, then does some work. The cleanup runs automatically on exit.

Bash Scripting

#!/bin/bash

# Create a temp file
tempfile="/tmp/mytempfile.txt"
touch "$tempfile"
echo "Temp file created: $tempfile"

# Define cleanup function
cleanup() {
  echo "Cleaning up..."
  rm -f "$tempfile"
  echo "Cleanup done."
}

# Set trap to call cleanup on script exit
trap cleanup EXIT

# Simulate work
echo "Doing some work..."
sleep 2

echo "Script finished."

Important Notes

The EXIT signal runs the trap code no matter how the script ends (normal exit, error, or Ctrl+C).

You can define a function for cleanup and call it in trap for cleaner code.

Use trap to avoid leaving temporary files or resources behind.

Summary

trap runs commands when your script exits or receives signals.

Use it to clean up files, close connections, or show messages.

It helps keep your system clean and your scripts safe.