View source for Command Line Examples: gawk

<code>gawk</code> is a powerful stream editor that can be used in command pipelines to perform special functions that do not have a command written for. The easiest use of gawk (and a very common one) is to manipulate the columns in text stream.

In the examples that follow, assume that a file name <code>test-data.txt</code> exists and contains 3 columns of data.
 <code>
 user@host: $ cat test-data.txt
 1  11  21
 2  12  22
 3  13  23
 4  14  24
 </code>


Print only columns 1 and 2 of the datafile
 <code>
 user@host: $ cat test-data.txt| gawk '{print $1,$2}'
 1 11
 2 12
 3 13
 4 14
 </code>


Print only columns 1 and 3 of the datafile
 <code>
 user@host: $ cat test-data.txt| gawk '{print $1,$3}'
 1 21
 2 22
 3 23
 4 24
 </code>


Print columns in reverse order
 <code>
 user@host: $ cat test-data.txt| gawk '{print $3,$2,$1}'
 21 11 1
 22 12 2
 23 13 3
 24 14 4
 </code>


Print all columns, but multiply column 2 by 100
 <code>
 user@host: $ cat test-data.txt| gawk '{print $1,100*$2,$3}'
 1 1100 21
 2 1200 22
 3 1300 23
 4 1400 24
 </code>


Print column 1 and column 3 squared
 <code>
 user@host: $ cat test-data.txt| gawk '{print $1,$3**2}'    
 1 441
 2 484
 3 529
 4 576
 </code>


Print column 1 and sine of column 1
 <code>
 user@host: $ cat test-data.txt| gawk '{print $1,sin($1)}'
 1 0.841471
 2 0.909297
 3 0.14112
 4 -0.756802
 </code>


Print columns 1 and 3 for all but the first two lines
 user@host: $ cat test-data.txt| gawk 'NR>2{print $1,$3}' 
 3 23
 4 24


Print columns 1 and 3 times some multiplication factor passed in as a varible
 user@host: $ scalefactor=4
 user@host: $ cat test-data.txt| gawk -v scale=${scalefactor} '{print $1,scale*$3}'
 1 84
 2 88
 3 92
 4 96