Linux Shell Scripting Essentials

Traps

When a process is running and in between we kill the process, the process terminates instantly without doing anything further. A programmer who writes a program may want to do some tasks before a program actually terminates; for example, a clean up of the temporary directories created, saving applications' state, saving logs, and so on. In such a case, a programmer would like to listen to signals and do the required task before actually allowing you to terminate the process.

Consider the following shell script example:

#!/bin/bash # Filename: my_app.sh # Description: Reverse a file echo "Enter file to be reversed" read filename tmpfile="/tmp/tmpfile.txt" # tac command is used to print a file in reverse order tac $filename > $tmpfile cp $tmpfile ...