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Help in Understanding awk if ( F ) syntax -

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# 1  
Old 05-13-2014
Help in Understanding awk if ( F ) syntax -
Hi Experts,

I was looking at the below link, for finding words next to it, And unable to understand this syntax:
Can any one please explain , what is meaning of this code:



Code:
if ( F )
s = s ? s OFS $i : $i

from:
HTML Code:
https://www.unix.com/unix-for-dummies-questions-and-answers/226523-match-pattern-after-certain-pattern-print-words-next-pattern.html
Thanks..
Last edited by vgersh99; 05-13-2014 at 07:45 PM.. Reason: fixed code tags for better understanding
# 2  
Old 05-13-2014
Code:
if ( F )
  s = s ? s OFS $i : $i

if expression F is true, then concatenate string 's' with value of field 'i' preceded with the output field separator OFS (if s is not empty). If 's' is empty assign the value of field 'i' to it.
It can be re-written as:
Code:
if ( F )
   if (s) 
     s= s OFS $i
   else
     s=$i

This User Gave Thanks to vgersh99 For This Post:
rveri
# 3  
Old 05-13-2014
F can only be true if F is 0 or 1 or has numeric value , is it correct. Thanks..
# 4  
Old 05-14-2014
Quote:
Originally Posted by rveri
F can only be true if F is 0 or 1 or has numeric value , is it correct. Thanks..

In awk, A true is defined as if it contains any non-zero numeric value or any non-empty string.

So in your case, if F is not null or not zero then its true.
# 5  
Old 05-14-2014
Quote:
Originally Posted by rveri
F can only be true if F is 0 or 1 or has numeric value , is it correct. Thanks..
Any non-blank string except 0 is 'true':
0False
1True
2True
 False
aTrue
abctrue
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