Linux

grep / sed / awk

The essential text processing trio — search, stream-edit and field-based processing on the command line.

grep – Search

grep "pattern" fileSearch for pattern in file

grep -r "pattern" ./dirSearch recursively in directory

grep -i "pattern" fileCase-insensitive search

grep -n "pattern" fileShow line numbers in output

grep -v "pattern" fileInvert match (lines NOT matching)

grep -c "pattern" fileCount matching lines

grep -l "pattern" *.logList files that have matches

grep -E "foo|bar" fileExtended regex — alternation

grep -o "pattern" filePrint only the matched part

grep -A 3 "pattern" fileShow 3 lines after each match

grep -B 3 "pattern" fileShow 3 lines before each match

grep -C 3 "pattern" fileShow 3 lines before and after

sed 's/old/new/' fileReplace first occurrence per line

sed 's/old/new/g' fileReplace all occurrences

sed 's/old/new/gi' fileReplace all, case-insensitive

sed -i 's/old/new/g' fileEdit file in-place

sed -i.bak 's/old/new/g' fileIn-place edit with .bak backup

sed -n '5,10p' filePrint lines 5 to 10

sed '3d' fileDelete line 3

sed '/pattern/d' fileDelete lines matching pattern

sed 's/^/ /' fileIndent every line by 2 spaces

sed 's/ *$//' fileStrip trailing whitespace

awk '{print $1}' filePrint first field of each line

awk '{print $NF}' filePrint last field

awk -F',' '{print $2}' fileSet comma as field separator

awk 'NR==5' filePrint line 5

awk 'NR>=5 && NR<=10' filePrint lines 5 to 10

awk '/pattern/' filePrint lines matching pattern

awk '{sum+=$1} END{print sum}' fileSum first column

awk '{print NR, $0}' filePrepend line numbers

awk '!seen[$0]++' fileRemove duplicate lines

awk '{print $2, $1}' fileSwap first two fields

awk 'length($0) > 80' filePrint lines longer than 80 chars