On 4/13/05, John Doe <[EMAIL PROTECTED]> wrote:
> Am Mittwoch, 13. April 2005 10.46 schrieb Ramprasad A Padmanabhan:
> > On Wed, 2005-04-13 at 12:32, Thomas Bätzler wrote:
> > > Ramprasad A Padmanabhan <[EMAIL PROTECTED]> asked:
> > > > I want to write a perl script like "gnu less".
> > > >
> > > > My perl script accepts input on STDIN or filename(s) as arguments.
> > > > If both are missing it should print the error message. How do
> > > > I do this ?
> > >
> > > There is always input on STDIN - even a straight eof could be input,
> > > like in "cat empty_file | ramprasads_less". You should probably try
> > > and check for filename arguments and revert to STDIN processing if
> > > there are none, i.e.
> > >
> > > my @files;
> > >
> > > if( @ARGV ){
> > > @files = @ARGV;
> > > } else {
> > > @files = ("-");
> > > }
> > >
> > > foreach my $file (@files){
> > > # transparent gzip decompression
> > > $file = "/usr/bin/gzip -d < $file|" if $file =~ m/\.gz$/;
> > >
> > > open( IN, $file ) or die "Cam't open '$file': $!";
> > > # do something
> > > close( IN );
> > > }
> > >
> > > HTH,
> > > Thomas
> >
> > That is perfectly ok .. but I require to print usage if there is no
> > input How do I do this ?
> >
> > Thanks
> > Ram
It depends how complex your options are going to be, but if you really
want to do it "like gnu", take a look at Getopt::Std and
Getopt::Long.
--jay
--
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
<http://learn.perl.org/> <http://learn.perl.org/first-response>
