6.2.1 Input from Files

In the following examples, the percent sign is a shell prompt. Please take note: In all examples where the command is nawk, use either awk or gawk if you are on an HP-UX flavor system or using Linux.

FORMAT

% nawk 'pattern' filename % nawk '{action}' filename % nawk 'pattern {action}' filename 

Here is a sample file called employees:

Example 6.1.

% cat employees Tom Jones 4424 5/12/66 543354 Mary Adams 5346 11/4/63 28765 Sally Chang 1654 7/22/54 650000 Billy Black 1683 9/23/44 336500 % nawk '/Mary/' employees Mary Adams 5346 11/4/63 28765 

EXPLANATION

Nawk prints all lines that contain the pattern Mary.

Example 6.2.

% cat employees Tom Jones 4424 5/12/66 543354 Mary Adams 5346 11/4/63 28765 Sally Chang 1654 7/22/54 650000 Billy Black 1683 9/23/44 336500 % nawk '{print $1}' employees Tom Mary Sally Billy 

EXPLANATION

Nawk prints the first field of file employees, where the field starts at the left margin of the line and is delimited by whitespace.

Example 6.3.

% cat employees Tom Jones 4424 5/12/66 543354 Mary Adams 5346 11/4/63 28765 Sally Chang 1654 7/22/54 650000 Billy Black 1683 9/23/44 336500 % nawk '/Sally/{print $1, $2}' employees Sally Chang 

EXPLANATION

Nawk prints the first and second fields of file employees, only if the line contains the pattern Sally. Remember, the field separator is whitespace.

6.2.2 Input from Commands

The output from a UNIX/Linux command or commands can be piped to awk for processing. Shell programs commonly use awk for manipulating commands.

FORMAT

% command | nawk 'pattern' % command | nawk '{action}' % command | nawk 'pattern {action}' 

Example 6.4.

1 % df | nawk '$4 > 75000' /oracle (/dev/dsk/c0t0d057 ):390780 blocks 105756 files /opt (/dev/dsk/c0t0d058 ):1943994 blocks 49187 files 2 % rusers | nawk '/root$/{print $1}' owl crow bluebird 

EXPLANATION