1.9 Summary
-  Programs in 
awk consist of pattern–action pairs.
 -  An action without a pattern always runs.  The default
action for a pattern without one is ‘{ print $0 }’.
 -  Use either
‘awk 'program' files’
or
‘awk -f program-file files’
to run 
awk.
 -  You may use the special ‘#!’ header line to create 
awk
programs that are directly executable.
 -  Comments in 
awk programs start with ‘#’ and continue to
the end of the same line.
 -  Be aware of quoting issues when writing 
awk programs as
part of a larger shell script (or MS-Windows batch file).
 -  You may use backslash continuation to continue a source line.
Lines are automatically continued after
a comma, open brace, question mark, colon,
‘||’, ‘&&’, 
do, and else.