Linux Text Processing

Powerful commands for text manipulation and searching.

grep - Search Text

# Search for pattern in file
grep "pattern" file.txt

# Case-insensitive search
grep -i "pattern" file.txt

# Recursive search in directories
grep -r "pattern" /path/to/dir

# Show line numbers
grep -n "pattern" file.txt

# Invert match (show non-matching lines)
grep -v "pattern" file.txt

sed - Stream Editor

# Replace first occurrence per line
sed 's/old/new/' file.txt

# Replace all occurrences
sed 's/old/new/g' file.txt

# Edit file in place
sed -i 's/old/new/g' file.txt

# Delete lines matching pattern
sed '/pattern/d' file.txt

awk - Pattern Processing

# Print specific column
awk '{print $1}' file.txt

# Print multiple columns
awk '{print $1, $3}' file.txt

# Field separator
awk -F':' '{print $1}' /etc/passwd

# Sum a column
awk '{sum += $1} END {print sum}' numbers.txt

Other Useful Commands

# Count lines, words, characters
wc -l file.txt

# Sort lines
sort file.txt

# Remove duplicate lines
sort -u file.txt

# First/last lines
head -n 10 file.txt
tail -n 10 file.txt

# Follow file updates in real-time
tail -f logfile.log