Bash Scripting For Loop

Hacking Truth

In Linux, all tasks from execution of services to loading and unloading of modules are carried out by programs and all programs need to be executed. You use the commands to access all the basic features of kernel. Shell scripting is a way to automate such tasks, and bash is one of the language, that has capabilities enough to be called as scripting as well as a language that can be used for programming on the POSIX platform, for small tasks.

Using For Loop:

The basic for loop declaration is shown in the following example. Create a file named ‘’ and add the following script using for loop. Here, for loop will iterate for 10 times and print all values of the variable, counter in single line.

Bash Scripting For Loop


for (( counter=10; counter>0; counter-- ))
echo -n "$counter "
printf "\n"

Run the file with bash command.

$ bash

Example-2: Reading Array Variable

You can use for loop to iterate the values of an array. Create a new bash file named with the following code.

ColorList=("Blue Green Pink White Red")
for color in $ColorList
if [ $color == 'Pink' ]
echo "My favorite color is $color"

In this example, the loop retrieves the values from an array variable named ColorList and it will print the output only if Pink value is found in the array elements.

Run the file with bash command.

$ bash

Example-4: Finding odd and even number using three expressions

The most common syntax of for loop is three expression syntax. First expression indicates initialization, second expression indicates termination condition and third expression indicates increment or decrement. Create a new file named to check the script.

for (( n=1; n<=5; n++ ))
if (( $n%2==0 ))
echo "$n is even"
echo "$n is odd"

The loop will iterate for 5 times from the value 1 to 5 and it will check and print even and odd numbers. You will get the following output after executing the script.

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