Linux Shell Scripting Cookbook - Third Edition

Reading a line explicitly using getline

The awk program reads an entire file by default. The getline function will read one line. This can be used to read header information from a file in the BEGIN block and then process actual data in the main block.

The syntax is getline var. The var variable will contain the line. If getline is called without an argument, we can access the content of the line with $0, $1, and $2.

Consider this example:

    $ seq 5 | awk 'BEGIN { getline; print "Read ahead first line", $0 }     
    { print $0 }'
    Read ahead first line 1 
    2
    3
    4
    5