Using xargs to Execute Commands Line by Line in Unix/Linux

Summary: Learn how to use xargs to execute a command once for each line of input in Unix/Linux systems. This guide covers basic usage, options, and examples to streamline your command-line operations.
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In Unix/Linux environments, xargs is a powerful command used to build and execute command lines from standard input. By default, xargs consolidates input and executes the command as few times as possible, but there are scenarios where you might want to execute the command once for each line of input. This guide will show you how to achieve this behavior.

Basic Usage of xargs

The typical syntax for xargs is:

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Executing a Command for Each Line

To make xargs execute a command once per line, the -L (or --max-lines) option is used. This option specifies the number of lines from the input that should be passed to each command execution. To process one line at a time, set -L to 1.

Here’s the general form:

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Practical Examples

Example 1: Removing Files Listed in a File

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You can use xargs to remove each file one by one:

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Example 2: Printing Each Line with a Prefix

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Use the following command:

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Here, the -I {} option replaces {} with the current line being processed.

Handling Edge Cases

Example 3: Handling Empty Lines

If your input contains empty lines and you want to skip them, you can use grep to filter them out before passing to xargs:

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Summary

Using xargs with the -L 1 option allows you to execute a command once per line of input, providing fine-grained control over command execution in scripts and command-line operations. Whether you're handling files, processing text, or performing batch operations, this technique can significantly enhance your workflow in Unix/Linux environments.