Awk

awk parses reports, among other text manipulation

Usage:

awk pattern {action}

Example:

awk '{print}' file.txt prints all of file.txt

awk '{print $3 "\t" $5}' file.txt prints just the third, and fifth columns of file.txt, separated by a tab.

Structure

BEGIN

BEGIN The begin block runs at the start of the awk program, and runs only once. The body block is optional.

BODY

/pattern/ {awk-commands} The body block runs on every line of text (this can be restricted with patterns.) There is no keyword for this block.

END

END {awk-commands} The END command runs once at the end of the program.

Operators

\ The \ tells awk that a special character follows the slash, and to interpret it differently than regular text
Example: \t means a tab character

$ field (column) reference
Example: $2 tells awk to do something to the 2nd field (column) of the input. (Note that awk does not interpret variables inside strings.)

' (single-quote) Specify awk commands inside single quotes at the command line.
Example: awk '{print}' file.txt prints the contents of file.txt to the screen

References

1. awk man page
2. awk tutorial