On Aug 13, 10:47 pm, [EMAIL PROTECTED] (Chas Owens) wrote:
> On 8/13/07, Jeff Pang <[EMAIL PROTECTED]> wrote:
>
>
>
> > -----Original Message-----
> > >From: [EMAIL PROTECTED]
> > >Sent: Aug 14, 2007 3:20 AM
> > >To: [EMAIL PROTECTED]
> > >Subject: piping and reading stdin
>
> > >I want to read from a pipe in my perl script invoked like:
>
> > >date | perl myperlscript.pl
>
> > >I understand that this puts the text outputted from the date program
> > >into the stdin. How could I check the buffer contained by the stdin
> > >without it blocking for you to input anything from the keyboard if
> > >nothing was piped in to the command.
>
> > >my perlscript contains something like:
>
> > >#this part im unsure about so im using functions that dont exist
> > >if(buffer_has_stuff_in_it(STDIN)){
> > > while(<STDIN>){
> > > print "$_\n";
> > > }
> > >}
> > >else{
> > > print "You didnt pipe anything into this program!\n";
> > >}
>
> > Hi,
>
> > You need an IO::Select object to be monitored,if it's timeouted,then die or
> > exit.
> > Just show my sample codes,hope this helps.
>
> > use strict;
> > use IO::Select;
>
> > my $timeout=1; # wait for 1 second
>
> > open PIPE,'cat|' or die $!; # since 'cat' doesn't input anything,program
> > would die after 1 sec.
> > my $oldhd=select PIPE;$|++;select $oldhd;
> > my $s = IO::Select->new();
> > $s->add(\*PIPE);
> > if (my @ready = $s->can_read($timeout)) {
> > my @content=<PIPE>;
> > print @content;
> > }else {
> > die "no input\n";
> > }
> > close PIPE;
>
> snip
>
> Another method is to use turn off blocking for STDIN. The following
> code should be run like this
>
> perl script.pl send | perl script.pl
>
> #!/usr/bin/perl
>
> use strict;
> use warnings;
> use IO::File;
>
> if (defined $ARGV[0] and $ARGV[0] eq 'send') {
> STDOUT->autoflush(1);
> for my $i (1 .. 10) {
> print "sending $i\n";
> sleep 3;
> }
> exit;
>
> }
>
> STDIN->blocking(0);
> my $timeout = 10;
> my $timer;
> while (1) {
> last if $timer++ > $timeout;
> local $_ = <STDIN>;
> if (defined) {
> print;
> $timer = 0;
> }
> sleep 1;
> print localtime() ."\n";
>
> }
Its not really making sense to me why you are adding sleep to this.
Cant I do this as fast as possible?
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