#!/usr/bin/perl

#----------------------------------------------------------------------------
# Copyright (C) 2001-2003 Ed Halley
#----------------------------------------------------------------------------

=head1 NAME

peek - eat lines of standard input; output a one-line preview instead

=head1 SYNOPSIS

    tar jcvf home.tar.bz2 /home | peek

=head1 DESCRIPTION

The peek process reads line-oriented text from the standard input, and
outputs each line atop each other on the standard output.  This is useful
for reducing visual clutter in large list-oriented processing while
keeping some visual feedback of the progress.

There are a few options to customize the style, but the defaults are
usually quite sufficient.

=cut

#-----------------------------------------------------------------------------

use Getopt::Long;

use warnings;
use strict;

my $wide = 79;
my $keep = 0;

my %options =
    ( 'wide|width=i' => \$wide,
      'keep!' => \$keep,
      );

GetOptions(%options) or die;

$wide = 0 if $wide < 1;

#-----------------------------------------------------------------------------

$| = 1;
while (<>)
{
    chomp;
    tr{\n\t}{\r };
    printf "%-${wide}.${wide}s\r", $_;
}
print ' 'x$wide, "\r" if not $keep;
print "\n" if $keep;
exit(0);

__END__

#-----------------------------------------------------------------------------

=head1 OPTIONS

=over 4

=item B<--width>=[integer]

Truncates the output lines to the given width, so as to avoid any line
wrapping issues.  Default is 79 characters wide.

=item B<--keep>

The final line of output is left visible on the display.

=head1 BUGS

The --width should default to the current terminal width, if it can be
determined.

This animation assumes that a carriage return (as opposed to a newline or
linefeed) will not erase the current line, but will return the output
cursor to the beginning of the current line.  This is a common convention
and holds true for many POSIX-styled terminals, but may not work for all
output devices.

=head1 LICENSE

Copyright (C) 2001-2003  Ed Halley  <ed@halley.cc>

This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.  For details on the Perl Artistic
License, read the F<http://www.perl.com/language/misc/Artistic.html>
page.

=cut