[lug] using sed.

[Detlef Brendle]

was das script aber nicht macht ist das original file aendern..
wie geht das nochmal?

----- Original Message -----
From: <rm at mamma.varadinet.de>
To: <lug at lug.boulder.co.us>
Sent: Monday, November 06, 2000 12:42 PM
Subject: Re: [lug] using sed.


> On Mon, Nov 06, 2000 at 12:15:56PM +0100, Detlef Brendle wrote:
> > hi folks
> > I m not a unix crack  and I just cant figure out why it doesnt work..
> > here is what I need todo.
> >
> > a - search a pattern (say "blank") within files located in this folder
and below.
> > b - replace the pattern found (if there is any) with a new text say
"blank extended" (this extension should be put into the file as parameter -
so I can adjust the new string as I need it.
> > c - replace the old file with the file holding the new changes.
> >
> > doesnt that sound pretty easy to u folks ?
> > its not for me ;(
>
> Does it need to be sed? It could be easily done in perl ...
>
> As a perl program you might start like this:
>
> #!/usr/bin/perl
>
>
> while (<>) {                     # <> is perl magic, it'll
>                                  # read lines from std. input
>                  # or from file(s) given as arguments
>
>   s/(blank)/${1}extension/go;    # substitute pattern with
>   print;                         # pattern + extension.
> }
>
> exit 0;
>
> Ok, that's an o.k. start, but we can do it easier.
> Perl has a handfull of commandline switches that
> make short scripts like the above even shorter (try
> 'perl -h' or 'man perl'). The '-p' switch wraps
> a  'while (<>) {[your script here]; print}'
> arround your script. So we get the following:
>
>   perl -p -e 's/(blank)/$1.extension/og;' dir/*
>
> Ah, but we want to substitute 'in place', so
> we need the '-i' switch as well:
>
>  perl -pi -e 's/(blank)/$1.extension/og;' dir/*
>
> But what happens if we change our mind or have
> a typo? The '-i' switch takes an optional
> parameter, the extension that should be added
> to backupfiles (if you don't give an extension
> there won't be any backup files!):
>
>  perl -ip .bu -e 's/(blank)/$1.extension/og;' dir/*
>
>
> Ralf
>
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