Cron For Win32

One thing about NT that amazed me was the lack of a job scheduler. NT is
supposed to be a wonderous server OS that's supposed to be able to replace
UNIX, but it doesn't have a job scheduler? What's wrong with this picture?

I needed one bad, so I wrote this cron clone in Perl. You'll need the Win32
Perl interpreter to run it.

I've been using this cron on Windows 95, too. Although Windows 95 has the
System Agent, it's an optional extra in the Plus! pack you may not want to
pay for, and old UNIX hands like me prefer the familiar interface of cron.

Download it!

You can:

  1. Download the program!. When you follow this link, do a "select all" in
     your browser (Control-A in Internet Explorer), copy the text, open a
     text editor, paste, and save.

     (Note this is a ".txt" file, because in my experience many browsers
     gag and die on an alien file extension that is not known as a MIME
     type.)
  2. Download Essential 97. Cron is distributed as part of Essential 97.
     This includes HTML format documentation.

Using Cron

If you need information on using cron in general, I recommend a good book
on UNIX system administration.

Usage:

cron <crontab file>

Where is a valid crontab file in the usual UNIX format. (Defaults to file
named "crontab" in current directory.) This is different from regular UNIX
cron.

If you're not familiar with crontab files, they have lines with the
following:

min hour monthday month weekday command

Lines beginning with '#' are comments and are ignored.
The numeric entries can be separated by commas – eg 1,2,3
Ranges for each are as follows:
minute (0-59),
hour (0-23),
day of the month (1-31),
month of the year (1-12),
day of the week (0-6 with 0=Sunday).

More Info On This Cron

Warning: this is not a complete implementation of cron! It's just the
features I needed for my own task automation. It's about 86% authentic,
when you discount the differences in starting it and security between UNIX
and NT.

UNIX cron features I do not support:

   * Ranges in entries (3,4,5,6 is okay, 3-6 is not)
   * Daylight savings time (schedule stuff some other time besides the
     overlap hour, or implement the logic and send me a copy!)
   * Embedded newlines in commands (run multiple commands from a script and
     run the script from cron)
   * Usage is different (on the command line, a crontab file is specified
     or the default "crontab" in the current directory is opened)
   * No security or allow/deny stuff (this implementation of cron assumes
     you're running from a single logged-on NT account)

Wish list for the future:

   * Support for ranges would be nice
   * DST logic
   * In-crontab "pragmas" or command line switches for log file and logging
     level
   * Leading 0 logic for date/times (so you won't see 10:3:4 for 10:03:04)
     – I wrote this once and will have to find it

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