Understanding Nested Loop working in Linux.
In this post, we will look how nested loop works in Linux Bash shell.
The loop works similar to any other programming language.
Nested loop refers to one or more loop(s) inside a loop.
OR, It can be defined as one or more iteration(s) nested inside an iteration.
OR, It can be defined as one or more iteration(s) nested inside an iteration.
Let us have a look at a nice example to understand how nested loop works.
Nested Loop Example
Create below script with 2 nested loops inside a loop.
[root@nglinux ~]# cat file1
#!/bin/bash
for a in {1..3}
{
for b in {a..c}
{
for c in {x..z}
{
echo "$a$b$c"
}
}
}
[root@nglinux ~]#
Output:
Now lets see the output of the above script on bash shell.
[root@nglinux ~]# ./file1 1ax 1ay 1az 1bx 1by 1bz 1cx 1cy 1cz 2ax 2ay 2az 2bx 2by 2bz 2cx 2cy 2cz 3ax 3ay 3az 3bx 3by 3bz 3cx 3cy 3cz
We can see above how three loops executed and prints the values of all three variables.
We can use the nested loop similarly to accomplish different tasks repeatedly.