How to pipe commands together in Linux

Pipes in Linux, represented by |, pass output from one command as input to another. For example, ls -l | grep ".txt" lists files and filters for .txt entries. Common uses include cat file.txt | sort for sorting text, ps aux | grep nginx to find nginx processes, df -h | awk '{print $5}' to extract disk usage, and history | tail -10 to show recent commands. Multiple pipes can be chained: ps aux | grep python | awk '{print $2}' | sort -u finds Python processes, extracts PIDs, and removes duplicates. Best practices include testing commands individually, filtering early with grep, and combining with redirection like ls | grep ".log" > logs.txt. Pipes enable efficient, script-free workflows by linking simple tools.

Chaining commands in Linux using pipes allows you to take the output of one command and use it as input for another. This is a powerful feature that enables efficient text processing and automation directly from the terminal.

Understanding the Pipe Operator

The pipe operator is represented by the vertical bar |. It redirects the standard output (stdout) of the command on its left to the standard input (stdin) of the command on its right.

ls -l | grep ".txt"
This lists all files in long format and then filters to show only lines containing .txt.

Common Use Cases and Examples

Pipes are widely used with text-processing tools. Here are practical combinations:

• cat file.txt | sort – Display contents of file.txt sorted alphabetically
• ps aux | grep nginx – Find running processes related to nginx
• df -h | awk '{print $5}' – Extract disk usage percentages from disk space report
• history | tail -10 – Show the last 10 commands from your command history

Combining Multiple Pipes

You can chain more than two commands together, processing data step by step.

ps aux | grep python | awk '{print $2}' | sort -u
This finds all Python processes, extracts their PIDs, then removes duplicates with sort -u.

Each stage refines the data further, letting you build complex operations from simple tools.

Best Practices and Tips

Pipes work best when each command does one thing well. Follow these tips for reliable results:

• Test each command separately before combining them
• Use grep early to reduce data passed through the pipeline
• Be aware that some commands buffer output, which may delay display
• Combine with redirection: ls | grep ".log" > logs.txt saves filtered output to a file

Basically, pipes help you turn small utilities into powerful workflows without temporary files or scripts.

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