AWK Command Examples for Text Processing

AWK is a powerful text-processing utility that excels at pattern scanning and processing. It reads input line by line and performs actions based on specified patterns. This cheat-sheet provides common AWK command examples to help you efficiently process and manipulate text data.

Basic Pattern Matching and Printing

Command	Description
awk '/pattern/ {print $1}'	Prints the first field of lines matching 'pattern' in standard Unix shells.
awk '/pattern/ {print "$1"}'	Prints the first field of lines matching 'pattern' when compiled with DJGPP, Cygwin.
awk "/pattern/ {print \"$1\"}"	Prints the first field of lines matching 'pattern' for GnuWin32, UnxUtils, Mingw.

Formatting and Spacing Text

Command	Description
awk '1;{print ""}'	Doubles the spacing of a file by printing a blank line after each original line.
awk 'BEGIN{ORS="\n\n"};1'	Another method to double-space a file using the Output Record Separator (ORS).
awk 'NF{print $0 "\n"}'	Doubles the spacing of a file that already contains blank lines, ensuring consistent spacing.
awk '1;{print "\n"}'	Triples the spacing of a file by printing two blank lines after each original line.

Line Numbering and Counting

Command	Description
awk '{print FNR "\t" $0}' files*	Prepends each line with its line number within its respective file (FNR).
awk '{print NR "\t" $0}' files*	Prepends each line with its line number across all files processed together (NR).
awk '{printf("%5d : %s\n", NR,$0)}'	Numbers each line of a file with right-aligned, padded numbers.
awk 'NF{$0=++a " :" $0};1'	Numbers each non-blank line of a file, prepending the line number.
awk 'END{print NR}'	Counts the total number of lines in the input, emulating wc -l.
awk '/Beth/{n++}; END {print n+0}' file	Counts the total number of lines that contain the pattern "Beth".

Field Manipulation and Calculations

Command	Description
awk '{s=0; for (i=1; i<=NF; i++) s=s+$i; print s}'	Prints the sum of all fields for each line.
awk '{for (i=1; i<=NF; i++) s=s+$i}; END{print s}'	Calculates and prints the sum of all fields across all lines in the input.
awk '{for (i=1; i<=NF; i++) if ($i < 0) $i = -$i; print }'	Replaces each negative field with its absolute value and prints the modified line.
awk '{for (i=1; i<=NF; i++) $i = ($i < 0) ? -$i : $i; print }'	An alternative way to replace negative fields with their absolute values.
awk '{ total = total + NF }; END {print total}' file	Prints the total count of fields (words) across all lines in a file.
awk '$1 > max {max=$1; maxline=$0}; END{ print max, maxline}'	Finds and prints the largest value in the first field and the entire line containing it.
awk '{ print NF ":" $0 }'	Prints the number of fields followed by the content of each line.
awk '{ print $NF }'	Prints only the last field of each line.
awk '{ field = $NF }; END{ print field }'	Prints the last field of the very last line of the input.
awk 'NF > 4'	Prints lines that contain more than 4 fields.
awk '$NF > 4'	Prints lines where the value of the last field is greater than 4.

Further Resources

• GNU AWK Manual
• MDN Web Docs: Date (for context on date/time processing)
• Stack Overflow: AWK Questions