sed inside awk Post: 302927287

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Top Forums UNIX for Dummies Questions & Answers sed inside awk Post 302927287 by Don Cragun on Tuesday 2nd of December 2014 12:20:29 AM

12-02-2014

Registered User

Quote:

Originally Posted by bakunin

... ... ...
Like RudiC rightfully said, awk can perform "global substitutions" (->gsub()) which do about the same as the "s/.../.../" (substitute) command in sed. It even uses the same regexps so the conversion of your sed statement should be pretty straightforward.
... ... ...

For the RE used in this example, the RE used by sed and the RE used by awk sub(...) are the same. In general, they aren't quite the same. The REs used by sed are defined to be basic regular expressions and the REs used by awk are defined to be extended regular expressions; so in some cases you can't directly use a sed substitute command BRE as an awk sub() or gsub() ERE.

Quote:

Originally Posted by RavinderSingh13

... ... ...

Code:

awk '{gsub(/.*\_/,X,$2);print $0}' Input_file

... ... ...

There is no need for the backslash in this ERE since underscore is not a special character in an ERE (nor in a BRE). And, there can't be more than one match for the ERE .*_ so gsub() isn't needed here; sub() will work just as well. And print $0 is longhand for print, so this can be simplified to:

Code:

awk '{sub(/.*_/,X,$2);print}' Input_file
        or even
awk '{sub(/.*_/,X,$2)}1' Input_file

Last edited by Don Cragun; 12-02-2014 at 01:22 AM.. Reason: Fix typo s/on/one/.

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