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How does Awk interpret $0!~

 
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Top Forums UNIX for Dummies Questions & Answers How does Awk interpret $0!~
# 1  
Old 12-28-2010
How does Awk interpret $0!~
I know $0 is the entire file's contents (at least I think that is what it is!), but what exactly is: $0!~

This was a snippet from a larger line
Code:
awk '$0!~/^$/ {print $0}'

This deletes blank lines, but I want to know specifically the $0!~ part... I am guessing /^$/ is regex for blank line... and {print $0} means to print the whole thing to stdout.. Right?
# 2  
Old 12-28-2010
Yes.
~ == >> "match"
!~ == >> "no match"
It prints lines which doesn't match with regular exp ^$ i.e. blank.
So prints all non-blank lines only (i.e. delete blank lines)
# 3  
Old 12-28-2010
$0 is one record (line) from the file. $1 is field #1, $2 is field #2..... depending on your field separator.
# 4  
Old 12-29-2010
How do you search for a regex in awk that is case insensitive?

awk '$0~ /case-insensitive-regex-here/'

Nevermind, I guess I got it, is this the best way?
Code:
 awk 'tolower ($0)~ /case-insensitive-regex-here/'

Last edited by glev2005; 12-29-2010 at 10:53 AM..
# 5  
Old 12-29-2010
Quote:
Originally Posted by glev2005
How do you search for a regex in awk that is case insensitive?

awk '$0 /case-insensitive-regex-here/'
Using next instruction:
Code:
BEGIN { IGNORECASE = 1; }

Regards,
Birei
# 6  
Old 12-29-2010
Quote:
Originally Posted by birei
Using next instruction:
Code:
BEGIN { IGNORECASE = 1; }

Regards,
Birei
Works only with gawk.
 
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