Hi Chris,
Thanks for your detailed email and for your time. I
think my second email crossed your email. The book I
read on Perl did not mention anything about first and
second half, and that didnt explain, me that we were
replacing all upsto last / by nothing. I thought it is
replacing with / itself.
anyway I will look into the tutorial, you have
mentioned in your email, before asking basic questions
like this.
if you know, any additional good book/tutorial let me
know.
thanks once again,
meena,
--- Chris Devers <[EMAIL PROTECTED]> wrote:
> On Sun, 19 Jun 2005, MEENA SELVAM wrote:
>
> > can anyone please explain?
>
> See `perldoc perlre`, or `man perlre`, or a book
> like _Learning Perl_ or
> _Mastering Regular Expressions_ for this kind of
> thing.
>
> It's really an introductory question that any decent
> introductory text
> should be able to cover for you.
>
> But, that said...
>
> > In the following code snippet, what is the meaning
> of
> > the pattern match
> > s/^.*\///
>
> The s/// is the substitution operator. It takes
> whatever is in the first
> half and replaces it with whatever is in the second
> half.
>
> In this case, the first half is the following
> pattern:
>
> /^.*\//
>
> Or, stripped of the forward-slashes that delimit the
> pattern:
>
> ^.*\/
>
> This means to match...
>
> ^ the start of the textt
> . a single character (basically, see references
> above for details)
> * zero or more of that which precedes
> \ an escape character; nullifies the special
> meaning of that which
> comes immediately afterward
> / a forward-slash
>
> Thus, it matches from the start of the string,
> matching anything at all
> (including nothing) from there to a '/' character.
> Because the match is
> being done greedily, if there are several '/'
> characters, it will match
> from the beginning up until the last foward-slash.
>
> The second half of the substitution is:
>
> //
>
> Or, stripped of the forward-slashes that delimit the
> pattern:
>
>
>
> That is, nothing at all.
>
> Thus, whenever the pattern in the first half is
> detected, it is deleted.
>
> Thus, since you're dealing with the program name
> (from $0), this code
> strips out the path information, leaving only the
> name of the program
> itself. Something like "/usr/local/bin/my_script.pl"
> will be reduced to
> simply "my_script.pl".
>
>
> Beyond this though, you really ought to be looking
> over some tutorials
> such as _Learning Perl_. They can do a very good job
> of answering all
> kinds of questions like this.
>
>
>
> --
> Chris Devers
>
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