Reading Multiple Arguments with For or While loop
We can use “@” variable to access every parameter passed to the script via the command line. It is a special variable that holds the array of variables in BASH. In this case, we are using it alone, so it contains the array of positional parameters passed in. We can use it to iterate over the parameters passed using loops or while loop as well.
#!/bin/bash
for i in $@
do
echo -e "$i\n"
done
Using loops and @ variable to access the parameters as array elements.
We used a range-based for loop to iterate over till there are elements in the @ array. We simply iterate over the array and print the element. We can simply assign it, modify the values, and make the required changes to the parameters and arguments to achieve the desired outcome from the script.
OR
We can also print the arguments using the while loop and the environmental variables of BASH.
#!/bin/bash
i=$(($#-1))
while [ $i -ge 0 ];
do
echo ${BASH_ARGV[$i]}
i=$((i-1))
done
Using while loop to iterate over the passed parameters.
We are using the variable ‘#‘ as it holds the number of parameters passed in. We initialize the number of parameters and take away one as we are going to use an array to iterate over it. So, as usual, the array’s index starts from 0. As this array is initialized from the last element or parameter passed, we need to decrement the counter until 0 to print every parameter in the order it is passed. We simply use the BASH_ARGV array to access the parameters and print its value. Also, at every iteration, we decrease the value of i- the iterator or counter by one using the arithmetic double braces. From this, we simply print every parameter passed to the script using a while loop as shown from the output screenshot.
How To Pass and Parse Linux Bash Script Arguments and Parameters
Parsing and Passing of Arguments into bash scripts/ shell scripts is quite similar to the way in which we pass arguments to the functions inside Bash scripts. We’ll see the actual process of passing on the arguments to a script and also look at the way to access those arguments inside the script.
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