On Tue, Dec 30, 2008 at 11:07:05PM +0200, Giorgos Keramidas wrote:
> On Tue, 30 Dec 2008 12:51:31 -0800, Gary Kline <kl...@thought.org> wrote:
> >     All right, then is this the right syntax.  In other words, do
> >     I need the double quotes to match the "http:" string?
> >
> >   perl -pi.bak -e 'print unless "/m/http:/" || eof; close ARGV if eof' *
> 
> Close, but not exactly right...
> 
> You have to keep in mind that the argument to -e is a Perl expression,
> i.e. something you might type as part of a script that looks like this:
> 
>     #!/usr/bin/perl
> 
>     while (<STDIN>) {
>         YOUR-EXPRESSION-HERE;
>         print $_;
>     }
> 
> One of the ways to print only the lines that do *not* match the
> "http://"; pattern is:
> 
>     print unless (m/http:\/\//);
> 
> Note how the '/' characters that are part of the m/.../ expression need
> extra backslashes to quote them.  You can avoid this by using another
> character for the m/.../ expression delimiter, like:


        i've used '%' rather than bangs because i wasn't sure if the
        bang might make the shell have a fit; great to know it
        won't:_)   [i try to avoid escapes when i can... .]


> 
>     print unless (m!http://!);
> 
> But you are not still done.  The while loop above already contains a
> print statement _outside_ of your expression.  So if you add this to a
> perl -p -e '...' invocation you are asking Perl to run this code:
> 
>     #!/usr/bin/perl
> 
>     while (<STDIN>) {
>         print unless (m!http://!);
>         print $_;
>     }
> 
> Each line of input will be printed _anyway_, but you will be duplicating
> all the non-http lines.  Use -n instead of -p to fix that:
> 
>     perl -n -e 'print unless (m!http://!)'
> 


        ahhhm, that's what happened last night.  i would up with dup
        lines (2) pointing me to different links.  had no clue.
        fortunately i had the .bak!


> A tiny detail that may be useful is that "http://"; is not required to be
> lowercase in URIs.  It may be worth adding the 'i' modifier after the
> second '!' of the URI matching expression:
> 
>     perl -n -e 'print unless (m!http://!i)'
> 
> Once you have that sort-of-working, it may be worth investigating more
> elaborate URI matching regexps, because this will match far too much
> (including, for instance, all the non-URI lines of this email that
> contain the regexp example itself).

        i shall check try a grep -ri http * >/usr/tmp/g.out
        and see what turns up.  thanks much,

        gary

> 

-- 
 Gary Kline  kl...@thought.org  http://www.thought.org  Public Service Unix
        http://jottings.thought.org   http://transfinite.thought.org
    The 2.17a release of Jottings: http://jottings.thought.org/index.php

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