awk syntax doubt - trailing 1 value - Shell Programming and Scripting

royalibrahim · #1 (**permalink**) 10-26-2008

In the below awk syntax, what does the value '1' signify?

awk '{....}1' file

some eg:

Code:

awk '{gsub(/[^[:cntrl:]]/,"")}1'
awk 'BEGIN{ORS=""}1'
awk '{ORS=(!(NR%5)?"":"\n")}1'

danmero · #2 (**permalink**) 10-26-2008

awk evaluates the 1 as true and the prints the entire line by default, including a newline.

Code:

echo 'foo' | awk '/foo/{print}1'

Take a look here: http://sunsite.ualberta.ca/Documenta...l#SEC_Contents

royalibrahim · #3 (**permalink**) 10-28-2008

Quote:

Originally Posted by danmero

awk evaluates the 1 as true and the prints the entire line by default, including a newline.

Code:

echo 'foo' | awk '/foo/{print}1'

Take a look here: The GNU Awk User's Guide: Table of Contents

But, what does 1 serve here or what is the role/purpose of 1?
Anyway, the default action of awk is to print the record right, even if the 'print' statement is missing?

danmero · #4 (**permalink**) 10-28-2008

Quote:

Originally Posted by royalibrahim

But, what does 1 serve here or what is the role/purpose of 1?
Anyway, the default action of awk is to print the record right, even if the 'print' statement is missing?

Don't take everything for granted.

Code:

$ echo 'foo' | awk '/foo/'            #default action
foo

$ echo 'foo' | awk '/foo/{print}'     #defined action
foo
$ echo 'foo' | awk '/foo/{$1="bar"}'  #defined action

$ echo 'foo' | awk '/foo/{print}1'    #defined action and default action
foo
foo

$ echo 'foo' | awk '/foo/{$1="bar"}1'
bar

royalibrahim · #5 (**permalink**) 10-28-2008

Thanks danmero, I got the essence !! hat's off

More UNIX and Linux Forum Topics You Might Find Helpful
Thread	Thread Starter	Forum	Replies	Last Post
Remove trailing G	Heathe_Kyle	Shell Programming and Scripting	3	04-14-2008 10:56 AM
How to remove trailing spaces	mahek_bedi	UNIX for Dummies Questions & Answers	2	08-10-2007 07:21 AM
Adding Trailing Spaces to a file	222001459	UNIX for Dummies Questions & Answers	1	11-04-2004 02:23 PM
Leading and Trailing Spaces	sleepster	Shell Programming and Scripting	7	10-29-2003 10:48 PM
re: removing trailing space from lines	oombera	Shell Programming and Scripting	1	06-19-2003 10:12 AM

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Display Modes	Rate This Thread
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode	Rate This Thread: