Click any command to expand the explanation and examples.
✂️ sed — Stream Editor
s/old/new/ — search and replace sed
# Replace first occurrence per line sed 's/old/new/' file.txtReplace ALL occurrences per line
sed ‘s/old/new/g’ file.txt
Case insensitive
sed ‘s/old/new/gi’ file.txt
Edit file in place
sed -i ‘s/old/new/g’ file.txt # Linux sed -i ” ‘s/old/new/g’ file.txt # macOS
Use different delimiter (useful with paths)
sed ‘s|/usr/local|/opt|g’ file.txt sed ‘s#http://#https://#g’ file.txt
Print, delete, insert lines sed
# Print specific lines sed -n '5p' file.txt # Line 5 sed -n '5,10p' file.txt # Lines 5-10 sed -n '/pattern/p' file.txt # Lines matching patternDelete lines
sed ‘5d’ file.txt # Delete line 5 sed ‘5,10d’ file.txt # Delete lines 5-10 sed ‘/pattern/d’ file.txt # Delete matching lines sed ’/^$/d’ file.txt # Delete empty lines sed ’/^#/d’ file.txt # Delete comment lines
Insert / append
sed ‘3i\New line before 3’ file.txt # Insert before line 3 sed ‘3a\New line after 3’ file.txt # Append after line 3 sed ‘1i\Header line’ file.txt # Add header
Replace entire line
sed ‘/pattern/c\Replacement line’ file.txt
sed one-liners sed
# Remove trailing whitespace sed 's/[[:space:]]*$//' file.txtRemove leading whitespace
sed ‘s/^[[:space:]]*//’ file.txt
Remove blank lines
sed ’/^$/d’ file.txt
Print between two patterns
sed -n ‘/START/,/END/p’ file.txt
Add line numbers
sed = file.txt | sed ‘N;s/\n/\t/’
Replace only on lines matching a pattern
sed ‘/error/s/old/new/g’ file.txt
Multiple operations
sed -e ‘s/foo/bar/g’ -e ‘s/baz/qux/g’ file.txt
📊 awk — Column Processing
Print columns awk
# Print specific columns (space-separated by default)
awk '{print $1}' file.txt # First column
awk '{print $2}' file.txt # Second column
awk '{print $NF}' file.txt # Last column
awk '{print $1, $3}' file.txt # First and third
Custom delimiter
awk -F’,’ ‘{print $1}’ data.csv # Comma
awk -F’:’ ‘{print $1}’ /etc/passwd # Colon
awk -F’\t’ ‘{print $2}’ data.tsv # Tab
Custom output separator
awk -F’,’ ‘{print $1, $2}’ OFS=‘\t’ data.csv
Print entire line
awk ‘{print $0}’ file.txt
awk ‘{print}’ file.txt # Same thing
Filtering rows awk
# Filter by column value awk '$3 > 100' file.txt # Third column > 100 awk '$1 == "Alice"' file.txt # First column is Alice awk '$2 ~ /error/' file.txt # Second column matches regex awk '$2 !~ /test/' file.txt # Doesn't matchFilter by line number
awk ‘NR == 5’ file.txt # Line 5 awk ‘NR >= 5 && NR <= 10’ file.txt # Lines 5-10 awk ‘NR > 1’ file.txt # Skip header
Filter by pattern
awk ‘/error/’ file.txt # Lines containing “error” awk ’!/^#/’ file.txt # Lines not starting with #
Aggregation and math awk
# Sum a column
awk '{sum += $1} END {print sum}' numbers.txt
Average
awk ‘{sum += $1; n++} END {print sum/n}’ numbers.txt
Count lines
awk ‘END {print NR}’ file.txt
Count matching lines
awk ‘/error/ {count++} END {print count}’ log.txt
Min / max
awk ‘NR==1 || $1 > max {max=$1} END {print max}’ numbers.txt
Frequency count
awk ‘{count[$1]++} END {for (k in count) print k, count[k]}’ file.txt | sort -rnk2
awk one-liners awk
# Remove duplicate lines (preserving order) awk '!seen[$0]++' file.txtPrint lines longer than 80 chars
awk ‘length > 80’ file.txt
Swap two columns
awk ‘{print $2, $1}’ file.txt
Add line numbers
awk ‘{print NR, $0}’ file.txt
Join lines with comma
awk ‘{printf “%s%s”, sep, $0; sep=”,”} END {print ""}’ file.txt
Convert CSV to TSV
awk -F’,’ ’{$1=$1; print}’ OFS=‘\t’ data.csv
Print between patterns
awk ‘/START/,/END/’ file.txt