search exact string

[Shellmaster]

Hello,

i have a small problem searching an exact String.

i want to make a substitution via sub("old","new") or gsub("old","new"). But i only want to the word "old" to be replaced.

Example :

old
older
gold

after using my awk-script i always get

new
newer
gnew

but what i want is

new
older
gold

can someone help me? I think its just a problem of the right reg. exp. or search string. i tried a lot but cant find it

thanks a lot

 

[feherke]

Hi

[tt]gawk[/tt] can do it :

awk '{gsub(/[highlight]\y[/highlight]old[highlight]\y[/highlight]/,"new")}1' /input/file

But I am afraid, other implementations can not handle the [tt]\y[/tt] metacharacter. Which is usually [tt]\b[/tt] in regular expressions.

Off-topic alternatives :

perl -pe 's/[highlight]\b[/highlight]old[highlight]\b[/highlight]/new/g' /input/file

sed 's/[highlight]\b[/highlight]old[highlight]\b[/highlight]/new/g' /input/file

Feherke.

http://free.rootshell.be/~feherke/

 

[Shellmaster]

Hey feherke,

thank yo very much it works fine to this point

now i want to put a LOOP variable into the regex like

for(i=1;i<=5,i++){

gsub(/\yoldi\y/,"new"i)

}

but it doesnt work, it always makes the i part of the String like "i" and not the reference to the number (1-5) of the variable.


greetings

 

[feherke]

Hi

You can not include variable names in the regular expression literal.

However in AWK you can use strings in place of regular expression literals :

[b]gsub[/b][teal]([/teal][green][i]"[/i][/green][lime][i]\\[/i][/lime][green][i]yold"[/i][/green]i[green][i]"[/i][/green][lime][i]\\[/i][/lime][green][i]y"[/i][/green][teal],[/teal][green][i]"new"[/i][/green][teal])[/teal]

Just pay attention to the metacharacters' backslashes ( \ ) as they must be escaped in string literals.


Feherke.

http://free.rootshell.be/~feherke/