Bash — Pipes

Basic pipes

#!/bin/bash

# Chain commands
ls -la | grep ".txt" | wc -l

# Count words in file
cat file.txt | wc -w

# Find large files
du -sh * | sort -rh | head -10

Pipe operators

#!/bin/bash

# Pipe
command1 | command2

# Pipe with error
command1 2>&1 | command2

# Tee (write to file and stdout)
echo "Hello" | tee file.txt
echo "World" | tee -a file.txt  # Append

Process substitution

#!/bin/bash

# Compare directory contents
diff <(ls dir1) <(ls dir2)

# Compare files
diff <(sort file1) <(sort file2)

Named pipes (FIFO)

#!/bin/bash

# Create named pipe
mkfifo /tmp/mypipe

# Writer (in one terminal)
echo "Hello" > /tmp/mypipe

# Reader (in another terminal)
cat /tmp/mypipe

Mini Practice

Write Bash code that:

1. Chains commands with pipes
2. Uses tee to write to file and stdout
3. Uses process substitution for comparison
4. Creates and uses a named pipe

Up Next

In the next lesson, you'll learn about Commands — essential Bash commands.