AWK is a powerful text processing language, ideal for data extraction, reporting, and data-reformatting. This cheatsheet provides quick commands and usage examples for various AWK tasks.
1. Basic Syntax
1.1 Print Entire File
awk '{print}' file.txt
# Prints every line of the file.1.2 Print Specific Columns
awk '{print $1, $3}' file.txt
# Prints the first and third columns of each line.2. Field Separator
2.1 Specify Field Separator
awk -F',' '{print $2}' file.csv
# Uses comma as the field separator and prints the second column.2.2 Multiple Field Separators
awk -F'[,:]' '{print $1, $2}' file.txt
# Uses either a comma or colon as the field separator.3. Pattern Matching
3.1 Print Lines Matching Pattern
awk '/pattern/ {print}' file.txt
# Prints lines that match 'pattern'.3.2 Print Lines Not Matching Pattern
awk '!/pattern/ {print}' file.txt
# Prints lines that do not match 'pattern'.4. Built-in Variables
4.1 Number of Records
awk 'END {print NR}' file.txt
# Prints the number of records processed.4.2 Filename
awk 'FNR==1 {print "Processing file:", FILENAME}' *.txt
# Prints filename of each file being processed.5. Conditional Statements
5.1 If-Else
awk '{if ($1 > 50) print $1, "High"; else print $1, "Low"}' file.txt
# Prints 'High' if the first column is greater than 50, otherwise 'Low'.5.2 Complex Conditions
awk '$1 > 50 && /pattern/ {print}' file.txt
# Prints lines where the first column is greater than 50 and 'pattern' is matched.6. Arrays
6.1 Using Arrays
awk '{array[$1]++}' END {for (i in array) print i, array[i]}' file.txt
# Counts occurrences of each unique value in the first column.7. String Functions
7.1 Length of String
awk '{print length($1)}' file.txt
# Prints the length of the first column.7.2 Substring
awk '{print substr($1, 1, 3)}' file.txt
# Prints the first three characters of the first column.8. Mathematical Functions
8.1 Random Number
awk 'BEGIN {srand(); print int(rand()*100)}'
# Prints a random number between 0 and 99.9. File Inclusion
9.1 Include Another AWK Script
awk -f script.awk file.txt
# Executes commands from 'script.awk' on 'file.txt'.