Bash Loops

Bash Loop Statements are used to execute a block of statements repeatedly based on a condition, or execute a block of statements for each element in a collection.

Bash Loops Tutorials

The following tutorials cover looping statements in Bash with detailed explanation and examples.

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Other Tutorials using Bash Loops

The following tutorials cover some of the scenarios where bash loops are used.

  • Bash While True

Examples

The following examples demonstrate how to use For, While and Until loop statements in bash scripting.

Bash For Loop

In the following script, we use For loop to iterate over elements of an array and execute a set of statement(s) for each item in the array.

Example.sh

arr=( "apple" "banana" "cherry" )
 
for i in "${arr[@]}"
do
    echo "Fruit : $i"
done

Output

Fruit : apple
Fruit : banana
Fruit : cherry

Bash While Loop

In the following script, we use While loop to print numbers from 0 to 9.

Example.sh

count=10
i=0

while [ $i -lt $count ];
do
   echo "$i"
   let i++
done

Output

0
1
2
3
4
5
6
7
8
9

Bash Until Loop

In the following script, we use for loop to iterate over elements of an array and execute a set of statement(s) for each item in the array.

Example.sh

count=10
i=0

until [ $i -gt $count ];
do
   echo "$i"
   let i++
done

Output

0
1
2
3
4
5
6
7
8
9
10

Difference Between While and Until Loops

The basic difference between While and Until loops is that: While loop stops when the condition is false, but, Until loop stops when the condition is true.

Conclusion

In this Bash Tutorial, we have learnt about the looping statements in Bash scripting, with examples.