awk utility vid
awk vs cat/grep vid
Description
mawk is an interpreter for the AWK Programming Language. The AWK language is
useful for manipulation of data files, text retrieval and processing, and for
prototyping and experimenting with algorithms. mawk is a new awk meaning it
implements the AWK language as defined in Aho, Kernighan and Weinberger, The
AWK Programming Language, Addison-Wesley Publishing, 1988 (hereafter referred
to as the AWK book.) mawk conforms to the POSIX 1003.2 (draft 11.3) defini‐
tion of the AWK language which contains a few features not described in the
AWK book, and mawk provides a small number of extensions.
An AWK program is a sequence of pattern {action} pairs and function defini‐
tions. Short programs are entered on the command line usually enclosed in ’ ’
to avoid shell interpretation. Longer programs can be read in from a file
with the -f option. Data input is read from the list of files on the command
line or from standard input when the list is empty. The input is broken into
records as determined by the record separator variable, RS. Initially, RS =
“\n” and records are synonymous with lines. Each record is compared against
each pattern and if it matches, the program text for {action} is executed.
Options
Given:
Frank
Testing 1
Hello World
TesT
123 Testing
1, $2, … are split column numbers
Then:
awk '{ print }' test.txt -> Raw output
awk '{ print $1}' test.txt -> First row of every line
awk '{ print $2}' test.txt -> Second row of every line or blank
awk '{ print $1,$2}' test.txt -> First and second row of every line, with ',' indicating a space between
awk '{ print $1.$2}' test.txt -> First and second row of every line, with '.' indicating direct concatenation
awk '/Test/ { print }' test.txt -> Print lines that have "Test" in it as a regex match
awk '{ if ($1 ~ /123/) print }' test.txt -> Print line if the first column matches 123
awk 'tolower($0) ~ /dir' test.txt -> Prints all lines with dir in the first column, caseless check
awk -F: '{print $2}' test.txt -> Uses -F flag to use F to seperate columns instead of whitespace
- Supports regex shortening,
[0-9], [a-z], ^, $,