This chapter shows how to create and call subroutines in a script.
The topics covered in this chapter are as follows:
- Show some simple subroutines.
- Show more advanced routines.
- Mention return codes again and how they work in scripts.
In the previous chapters we have seen mostly simple scripts that were not very complicated. Scripts can actually do a whole lot more which we are about to see.
First, let's start with a selection of simple but powerful scripts. These are mainly shown to give the reader an idea of just what can be done quickly with a script.
The tput clear terminal command can be used to clear the current command-line session. You could type tput clear all the time, but wouldn't just cls be nicer?
Here's a simple script that clears the current screen:
#!/bin/sh # # 5/8/2017 # tput clear
Notice that this was so simple I didn't even bother to include a Usage message or return code. Remember, to make this a command on your system do this:
cd $HOME/bin- create/edit a file named
cls - copy and paste the preceding code into this file
- save the file
- run
chmod 755 cls
You can now type cls from any terminal (under that user) and your screen will clear. Try it.