Awk usage (1)

An awk program is composed of a cycle of the main input. A loop is a routine and will be executed repeatedly until some conditions exist to terminate it. The main input loop is a routine. Number of cycles = number of objects.

Awk can write two special routines, begin and end.

 

Cat name

=>

John Robinson, Koren inc., 978 4th Ave., Boston, MA: 01760,696-0987
Phyllis Chapman, Gve Corp., 34 sea drive, amesbury, MA: 01881,879-0900

Bulent green, wR Corp., 46 win, Alameda, MA: 93253,356-3635

Lily Smith, beyondsoft Corp., 28 win, Beijing, BJ: 2535,010-4546

 

Specify a separator in the awk

 

Use the-F parameter

 

Awk-F "/t" '{print $1}' # use a tab as the Separator

 

Use FS system variables

 

Awk 'in in {FS = ","} {print $1} 'name # fs is a space by default.

 

You can also use regular expressions to specify separators.

 

Awk-F "[,:]" '{print $6}' name

 

 

Determine whether the fields match in the awk

Sed-n'/^ $ /! P' name | awk-F "," '$5 !~ /MA/{print $1 "," $6 }'

=>

Lily Smith, 010-4546

 

Use of variables in awk

Awk '/^ $/{x ++} end {print x}' name # Number of printed Spaces

=> 3

 

Cat scre

=>

John 85 92 78 94 88
Andrea 89 90 75 90 86
Jasper 84 88 80 92 84

 

Awk '{Total = $2 + $3 + $4 + $5 + $6; AVG = total/5; print $1, AVG}' score # print the name and average score

=>

John 87.4
Andrea 86
Jason 85.6