Passing Command Line Arguments to Bash Scripts

To pass an argument to your Bash script, your just need to write it after the name of your script:

./script.sh my_argument

In our Bash script, there are several reserved/pre-defined variables which we can use to recall the user-defined parameters. The first argument is stored in $1, the second in $2, the third in $3…and so on. We cannot use $0 as that references your Bash script itself.

Let’s see how this works using an example script:

#!/usr/bin/env bash
 
echo "The first fruit is: $1"
echo "The second fruit is: $2"
echo "The third fruit is: $3"

If we run our script and don’t give an argument, we will see no output for our pre-defined variables:

./script.sh
The first fruit is:
The second fruit is:
The third fruit is:

Alternatively, if we provide three fruits, our script detects these and will return those values back to use via the pre-defined variables.

./fruit.sh apple pear orange
The first fruit is: apple
The second fruit is: pear
The third fruit is: orange

Sometimes, we may want to access all of the arguments. We can do this using $@.

Let’s update our example script to return all of the fruits provided as arguments to the script as well:

#!/usr/bin/env bash
 
echo "The first fruit is: $1"
echo "The second fruit is: $2"
echo "The third fruit is: $3"
echo "All fruits are: $@"

When we run our script, you can see that we now have an extra output which lists all of the fruits we gave to our script on the command line.

./fruit.sh apple pear orange
The first fruit is: apple
The second fruit is: pear
The third fruit is: orange
All fruits are: apple pear orange