sourcecode
halley
<code>
#!/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
</code>
Some commands give visual feedback that is either feast or flood. They either remain blissfully silent while they work on a long task, or they blather endlessly about every step of their progress.
<p>Many times, it'd be handy to have feedback somewhere in between. You can still see it's running, but it doesn't scroll your terminal out of sight.
<p>This is essentially a Perl one-liner, written to a script. It's trivial. It's not about how tough the task is, but whether you find it useful.
<p><b>Update</b>: printf and --keep suggestions implemented
Utility Scripts
Ed Halley <ed@halley.cc> This program is free software; you can redistribute it and/or modify it under the same terms as Perl