# Display file contents
cat file.txt
# Display multiple files
cat file1.txt file2.txt file3.txt
# Concatenate files into new file
cat file1.txt file2.txt > combined.txt
# Number lines
cat -n file.txt
# Show line endings and tabs
cat -A file.txt
# Remove blank lines
cat -s file.txt # Squeeze multiple blank lines to one
# Create file with cat (Ctrl+D to end)
cat > newfile.txt
This is content
More content
^D
# Save to file AND display
command | tee output.txt
# Save to multiple files
command | tee file1.txt file2.txt
# Append to file
command | tee -a logfile.txt
# Practical examples
ps aux | tee processes.txt | grep firefox
ls -la | tee directory_listing.txt | wc -l
cat /etc/passwd | tee users_backup.txt | head -5
Next: → Grep Pattern Matching Master
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Lesson Home: ↑ Lesson 7: Filters & Pipelines
Course Home: ⌂ Introduction to Linux