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.

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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.

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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.

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.

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.

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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.