Working with Linux

Shell scripting for fun and profit
Pipes and subshells are one way of expanding the capabilities of our shell. The ultimate way is by
writing shell scripts. These scenarios must be taken into consideration when dealing with complex
tasks that can't be automated with a one-line command.
The good news is that almost all the tasks can be automated with the use of shell scripts. We won't go
over an introduction to shell scripts. Instead, we will be looking at some more advanced use cases for
writing them.
Let's start our journey into shell scripting! First thing, let's open a file called script.sh and split the
screen so that we can test while writing. Every shell should start with #!, followed by the interpreter
it uses. This line is called a shebang. We will be using bash as our default interpreter.
It's a good idea to use bash, because it's a common interpreter that comes with most Linux
distributions and also OS X:
#!/bin/bash
Let's start with a simple use case: reading the arguments passed into the command line. We will
assign the value of the first command line argument, $1, to a variable called ARG, and then print it
back to the screen:
ARG=${1}
echo ${ARG}
Let's save our script, assign it execution permissions, and then run it with one argument:
./script.sh test