Re: possible gawk bug

[Aharon Robbins]

Greetings.  Re this:

> Date: Tue, 17 Dec 2002 09:24:16 +0100
> From: Helge Skrivervik <address@hidden>
> To: address@hidden
> Subject: possible gawk bug
>
> the sub/gsub fundtion does not seem to be able to make the substitution 
> of '&' to '\&', and I have come to the conclusion that this is most 
> likely a bug. From the docs I would expect the correct syntax to be 
> sub(/&/,"\\\&"), but while '\\' and '\&' alone work as substitutions, 
> the combination does not. the gawk version is 3.1.1.(redhat 8)
>
> rgds,
> helge

$ echo 'escape me: & done' | gawk '{ sub(/&/, "\\\\&"); print }'
escape me: \& done

This general issue is discussed in the gawk doc.  There are two levels
of processing: string scanning, and sub/gsub replacement.  For string
scanning, gawk removes 1 level of backslash, thus sub sees the string
containing "\\&".

See node `Gory Details', which is section "More About \ and & with
sub, gsub, and gensub" in the printed doc.

Arnold