Linux Pipelines

Think of Linux pipelines like a factory assembly line. Just as raw materials move from one station to another, getting transformed at each step, data flows through a series of commands, getting processed and transformed along the way. The pipe symbol (|) is like the conveyor belt that moves the data from one command to the next.

When to Use Pipelines

Use pipelines when you want to:

• Combine multiple commands to perform complex tasks
• Process data step by step without creating temporary files
• Filter and transform data in a single command
• Create powerful one-liners for data analysis
• Build custom data processing workflows

Basic Pipeline Concepts

A pipeline connects commands using the pipe symbol (|). The output of the command on the left becomes the input for the command on the right. Think of it like a chain of commands, where each link processes the data in some way.

Common Pipeline Patterns

Practical Examples

# Find all text files containing "error"
ls *.txt | grep "error"

# Count how many Python files are in a directory
ls *.py | wc -l

# Sort files by size
ls -l | sort -k5 -n

# Convert text to uppercase and count lines
cat file.txt | tr '[:lower:]' '[:upper:]' | wc -l

# Extract usernames from /etc/passwd
cat /etc/passwd | cut -d: -f1 | sort

# Find unique IP addresses in a log file
grep "IP:" access.log | cut -d' ' -f2 | sort -u

# Show top 5 memory-consuming processes
ps aux | sort -k4 -nr | head -n 5

# Monitor disk usage
df -h | grep "/dev/sd" | sort -k5 -nr

# Count running processes for a user
ps aux | grep username | wc -l

Tips for Success

• Start simple: Begin with two commands and add more as needed
• Test each step: Run each command separately first
• Use comments: Add comments to explain complex pipelines
• Break it down: Build pipelines step by step

Common Mistakes to Avoid

• Forgetting that some commands don't work well in pipelines
• Not checking if the first command produces the expected output
• Creating overly complex pipelines when a simpler solution exists
• Not using proper quoting for special characters

Best Practices

• Keep pipelines readable by using line breaks for long commands
• Use meaningful variable names when storing pipeline output
• Add comments to explain complex pipelines
• Test each part of the pipeline separately
• Use proper error handling

Advanced Pipeline Techniques

# Find and process specific files
find . -name "*.log" | xargs grep "error" | sort | uniq -c

# Monitor system resources
top -b -n 1 | head -n 10 | tee system_stats.txt

# Process CSV data
cat data.csv | cut -d',' -f1,3 | sort | uniq -c | sort -nr