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AWK Command Cheatsheet

Table of Contents

Basic Syntax

Terminal window
awk 'pattern { action }' file
  • pattern: Condition to match (optional)
  • action: Operation to perform when pattern matches
  • file: Input file (optional, can use stdin)

Built-in Variables

Terminal window
$0      # Entire current line
$1-$n   # Field numbers (columns)
NF      # Number of fields in current record
NR      # Current record (line) number
FNR     # Record number in current file
FILENAME # Current input filename

Field Operations

Terminal window
# Print specific fields
awk '{print $1, $3, $NF}'          # First, third, and last fields
awk '{print $(NF-1)}'              # Second-to-last field
awk '{print NF}'                   # Number of fields in line


# Field manipulation
awk '{$1=$1; print}'               # Force field recalculation
awk '{$2="new"; print}'            # Change second field

Text Processing

Terminal window
# Match in specific field
awk '$1 ~ /pattern/'               # Pattern in first field
awk '$NF ~ /pattern/'              # Pattern in last field


# Multiple patterns
awk '/pattern1/ && /pattern2/'
awk '$1 ~ /pattern/ || $2 > 100'

Advanced Field Processing

Terminal window
# Custom field separator
awk -F',' '{print $1, $2}'         # CSV files
awk -F':' '{print $1, $NF}'        # System files


# Multiple separators
awk -F'[,:;]' '{print $1, $2}'


# Change separator for output
awk 'BEGIN{OFS=","} {print $1, $2}'

Practical Examples

Log File Processing

Terminal window
# Count HTTP status codes
awk '$9 ~ /^[0-9]/ {codes[$9]++}
     END {for (code in codes)
          print code, codes[code]}' access.log


# Find error messages
awk '$3 == "ERROR" {print $0}' logfile.txt


# Time-based filtering
awk '$1 > "2023-01-01" {print $0}' dated_log.txt

Data Analysis

Terminal window
# Column statistics
awk '{
    sum += $1
    sumsq += $1 * $1
}
END {
    print "Count:", NR
    print "Sum:", sum
    print "Average:", sum/NR
    print "Std Dev:", sqrt(sumsq/NR - (sum/NR)^2)
}' data.txt


# Frequency count
awk '{count[$1]++}
     END {for (word in count)
          printf "%-20s %d\n", word, count[word]}'

File Operations

Terminal window
# Numbered output
awk '{printf "%5d : %s\n", NR, $0}'


# Format CSV as table
awk -F',' '{printf "%-20s %-10s %s\n", $1, $2, $3}'


# Remove duplicate lines
awk '!seen[$0]++'