A while back I created a TODO file to keep track of things I wanted to get done. This way I would not have to think about everything I wanted to do because it was noted somewhere. I had a cron job mail the file to me every morning at 7:00.

I thought about writing a tool to allow me to add and remove items. I realized that it would be easy to setup a shell alias to edit a file. I made it so I just had to type "todo" instead of "emacs ~/TODO". Eventually I shortened it to the single letter command "t".

After a while I noticed I wanted to be able to list the items without opening and exiting an editor. It would be reasonable to want to run "t -l" to list the file. That lead to the following script. The usage message looks like:

[frink@truth:~]$ t -h

usage: /home/frink/code/scripts/todo.pl [options]

where [options] are:
   -e , --editor  specify an alternate editor like "vi"
   -h , --help    this usage message
   -l , --list    list the file contents instead of editing
   -p , --pager   specify an alternate pager program like "more" or "cat"

examples:
   todo.pl
   todo.pl -l
   todo.pl -e vi
   todo.pl -l -p head
   todo.pl -l -p cat
   todo.pl -l -p more
   todo.pl -l -p "mail -S \"TODO reminders\" me@domain.com"

#!/usr/bin/perl -w
#
# file: /home/frink/code/scripts/todo.pl
# purpose: manage my TODO file.
#
# chad c d clark < email: frink-todo.pl *at* superfrink *dot* com >
# created: 2005-03-26
# updated: 2006-01-24 added -e , -h , -l , -p
# $Id$

use strict;
use Getopt::Long;

sub list_file($);
sub usage_mesage();

# -- set the global settings -- 
my %G;
$G{editor}      = "emacs";            # editor to use
$G{todo_file}   = "/home/chad/TODO";  # TODO file
$G{usage_only}  = 0;                  # display usage message
$G{list_only}   = 0;                  # dump file contents
$G{list_pager}  = "less";             # output pager program

# -- get the command line args -- 
GetOptions ("e|editor=s" => \$G{editor},
            "h|help"     => \$G{usage_only},
            "l|list"     => \$G{list_only},
            "p|pager=s"  => \$G{list_pager})
    or die("Problem with command line options.  $!\n");


# -- now take the requested action --

# if a usage message was requests print one and exit
if($G{usage_only}) { usage_mesage(); exit(0); }

# if a contents list was requested then list the file and exit
if($G{list_only}) { list_file($G{todo_file}); exit(0); }

# -- if we get here we need to open the file for editing --

# make sure the file exists.
unless(-e $G{todo_file}) { `touch $G{todo_file}`; }

# open the file for editing.
my $cmd = "$G{editor} $G{todo_file}";
print $cmd, "\n";
exec $cmd;

# -- we should never get here --
die("$0 : exec($cmd) failed.  $!\n");


# -- subroutines ----------------------------------------------------

sub usage_mesage() {

    # try to get a shorter version of the current program name.
    # (some people might not have File::Basename.)
    my $me = $0;
    if ($0 =~ m/^(.*\/)(.*)$/) { $me = $2; }

print qq{
usage: $0 [options]

where [options] are:
   -e , --editor  specify an alternate editor like "vi"
   -h , --help    this usage message
   -l , --list    list the file contents instead of editing
   -p , --pager   specify an alternate pager program like "more" or "cat"

examples:
   $me
   $me -l
   $me -e vi
   $me -l -p head
   $me -l -p cat
   $me -l -p more
   $me -l -p "mail -S \\\"TODO reminders\\\" me\@domain.com"

};
}

sub list_file($) {
# purpose: dump the file using an optional pager program
# globals used:
#   $G{list_pager} - pager program, eg "less" or "cat"

    my $fname = shift;
    unless ($fname)    { die ("No file specified.\n"); }
    unless (-e $fname) { die ("File does not exist '$fname'.\n"); }
    unless (-r $fname) { die ("File is not readable '$fname'.\n"); }

    # open the input file
    open FH , "<" , $fname or die("Unable to open file '$fname'.  $!\n");

    # if there is a pager program then use it
    if($G{list_pager}) {

        open PAGER , "|-" , $G{list_pager}
            or die("Unable to open file '$G{list_pager}'.  $!\n");

        while() { print PAGER; }

        close PAGER;

    # else there is no pager program so just print the file contents
    } else {

        while() { print; }
    }

    # close the input file
    close FH;
}