xargs — Execute Commands from Input

xargs reads input and passes it as arguments to a command.

Why xargs?

Some commands don't accept stdin as arguments. xargs bridges the gap.

Basic usage

find . -name "*.txt" | xargs cat          # Cat all .txt files
find . -name "*.log" | xargs rm           # Delete all .log files
echo "file1 file2 file3" | xargs ls -la

Safer with null delimiter

find . -name "*.txt" -print0 | xargs -0 rm

-print0 and -0 use null bytes as delimiters — safe for filenames with spaces.

Parallel execution

cat urls.txt | xargs -P 4 wget           # Download 4 at a time
find . -name "*.jpg" | xargs -P 8 -I{} convert {} {}.png

-I{} placeholder

find . -name "*.txt" | xargs -I{} cp {} /backup/{}
cat names.txt | xargs -I{} echo "Hello, {}!"

Limit arguments per invocation

xargs -n 1 command    # One arg per command call
xargs -n 3 command    # Three args per call

Practical examples

# Compress all logs older than 7 days
find /var/log -name '*.log' -mtime +7 | xargs gzip

# Count lines in all Python files
find . -name '*.py' | xargs wc -l

# Search for text in all .conf files
find /etc -name '*.conf' | xargs grep -l 'ServerName'