Bash For Loop

Bash For Loop

In Bash scripting, the for loop allows you to iterate over a list of items or a range of numbers, executing a block of commands for each item in the list or number in the range.

Syntax

for variable in list; do
    # commands
done

The basic syntax involves using for followed by a variable name, the in keyword, a list of items, and the commands to execute for each item in the list. The loop is ended with done.

Example Bash For Loops

Let's look at some examples of how to use for loops in Bash:

1. For Loop to Iterate Over a List of Strings

This script iterates over a list of names and prints each name.

#!/bin/bash

for name in Alice Bob Charlie; do
    echo "Hello, $name!"
done

In this script, the for loop iterates over the list of names 'Alice', 'Bob', and 'Charlie'. For each name, the loop prints a greeting message.

For loop to iterate over a list of strings in Bash

2. For Loop to Iterate Over a Range of Numbers

This script iterates over a range of numbers from 1 to 5 and prints each number.

#!/bin/bash

for number in {1..5}; do
    echo "Number: $number"
done

In this script, the for loop iterates over the range of numbers from 1 to 5. For each number, the loop prints the number.

For loop to iterate over a range of numbers in Bash

3. For Loop to Iterate Over Files in a Directory

This script iterates over all the files in the current directory and prints the name of each file.

#!/bin/bash

for file in *; do
    echo "File: $file"
done

In this script, the for loop iterates over all the files in the current directory (denoted by *). For each file, the loop prints the file name.

Conclusion

The Bash for loop is a crucial tool for repetitive tasks in shell scripting. Understanding how to use for loops can help you automate and simplify many tasks in your scripts.