Typo

[linux_from_scratch_hints.git] / OLD / fcrond-hint.txt

TITLE:          Fcron Scheduling Daemon
LFS VERSION:    4.0 (or older versions, with minor changes)
AUTHOR:         Lyle Vogtmann <vogtmann@pioneernet.net>
MAINTAINER:     Robert Park <rbpark@ualberta.ca>

SYNOPSIS:
        How to set up the fcron scheduling daemon on an LFS system.

HINT:

Changelog
---------

Revision 1.8  2003/01/22 07:55:04  feztaa
Updated cronmail script to version 1.6

Revision 1.7  2002/12/24 08:30:05  feztaa
Updated to fcron 2.9.3.

Revision 1.6  2002/09/15 05:38:52  feztaa
Changed email address, among other misc fixes.

Revision 1.5  2002/06/09 04:14:05  feztaa
Added some notes, changed style of code blocks, and fixed a couple typos.

Revision 1.4  2002/05/02 00:05:36  feztaa
Fixed a problem with the cronmail script improperly delivering mail,
clarified some abiguities, and reduced some redundancy in the fcrontabs.

Revision 1.3  2002/04/27 19:28:08  feztaa
Fixed various typos and other grammatical errors (oops ;)

Revision 1.2  2002/04/27 19:17:48  feztaa
I've taken over maintenance of this hint from Lyle.
Added 'cronmail' script, updated bootscripts to LFS 3.3,
and reformatted the layout of the hint.

Intro
-----

I wrote this to help others set up and use the Vixie Cron replacement known as
fcron. Cron is a very useful and nearly ever-present system daemon on
Unix-like systems.  It is started at boot time and runs in the background,
starting sheduled tasks specified in a "crontab". There are several versions of
cron available, each with it's own additions and features. Fcron has a mixture
of some of the best features.

Fcron can function as a standard cron, running tasks at a certain time on a
certain day. It can also function like anacron, running tasks after a certain
amount of time at an unspecific time (if you don't leave your computer on all
the time, this is a godsend). It can also run tasks after a certain amount of
uptime, too.

For more information, check out the fcron home page at http://fcron.free.fr.

Notes
-----

In an attempt to make this easier to read, all "code blocks" that you should
execute on the commandline start and end with "##--CODE--##". Feel free to copy
that onto the commandline along with the code itself, it won't hurt anything.
Also, for quoted text (the output of a program, for example), each line is
prefixed with four spaces.

Requirements
------------

If you want to see the output of the commands that Fcron runs, you will want to
have a working mail system installed. If you are not interested in installing a
mail system on your box, I have written a "cronmail" script that you can use to
let fcron deliver mail to you without a full MTA on the system. You will need
to install the procmail package, though, because my cronmail script uses
formail (which comes with procmail).

This hint does not cover setting up a local mail service, but I'll show you how
to install cronmail. If you want to set up a local mail service, check out the
LDP at http://www.linuxdoc.org. I reccommend Postfix, http://www.postfix.org.

Instructions
------------

1. Get fcron sources from http://fcron.free.fr and unpack them. I use fcron
2.9.3, but this hint should work for other versions as well.

2. Add the "fcron" user and group to your system:

##--CODE--##
groupadd -g 13 fcron
useradd -u 13 -g fcron -d /dev/null -s /bin/false fcron
##--CODE--##

This creates the group fcron with GID 13 and the user fcron with UID 13. It
also prevents anybody from logging into this account, because the home
directory is /dev/null and and the shell is /bin/false.

3. Run configure:

##--CODE--##
./configure --prefix=/usr --with-spooldir=/var/lib/fcron
##--CODE--##

This tells fcron to put it's fcrontab files into /var/lib/fcron.  I personally
use /var/fcron, but if you want to be FHS-compliant, you have to use
/var/lib/fcron.

4. You might want to have a glance at config.h to make any changes to the build
process, but in my experience this is unneccessary. If you do edit this file,
be sure to check the locations of key files like fcron.allow, fcron.deny, etc.
You can also configure what Fcron calls itself when it mails you, if you like.

5. Compile:

##--CODE--##
make && su -c "make install"
##--CODE--##

This will compile the sources, then install them as root. When it asks you to
install the init script, don't. We are going to make our own, better init
script later on.

7. If you are upgrading, be sure to run this command for each user on your
system that had an fcrontab during installation:

##--CODE--##
fcrontab -u <user> -z
##--CODE--##

This simply updates the fcrontab, in case the format has changed.

8. Now we will create the bootscripts. Run this as root:

##--CODE--##
cat >/etc/rc.d/init.d/fcron <<"EOF"
#!/bin/bash
# Begin $rc_base/init.d/fcron

source /etc/sysconfig/rc
source $rc_functions

case "$1" in
  start)
    echo "Starting fcron..."
    loadproc /usr/sbin/fcron
    ;;

  stop)
    echo "Stopping fcron..."
    killproc fcron
    ;;

  restart)
    $0 stop
    sleep 1
    $0 start
    ;;

  status)
    statusproc fcron
    ;;

  *)
    echo "Usage: $0 {start|stop|restart|status}"
    exit 1
    ;;
esac

# End $rc_base/init.d/fcron
EOF
chmod 755 /etc/rc.d/init.d/fcron
##--CODE--##

You will also need to make the symlinks in the appropriate directories. I did
mine like this, but you might want to do it differently:

##--CODE--##
cd /etc/rc.d/rc0.d &&
ln -s ../init.d/fcron K35fcron &&
cd /etc/rc.d/rc6.d &&
ln -s ../init.d/fcron K35fcron &&
cd /etc/rc.d/rc3.d &&
ln -s ../init.d/fcron S60fcron
##--CODE--##

9. You need to give it some tasks to do (it wouldn't be very useful
otherwise! ;). Read the man page for fcrontab:

##--CODE--##
man 5 fcrontab
##--CODE--##

If you need some examples to get started, this is what I have in root's
fcrontab: (this is the output of 'fcrontab -l')

    !mailto(feztaa),mail(yes),forcemail(yes),noticenotrun(yes)
    %daily * 9-15 updatedb --prunepaths="/mnt /proc /dev"
    %daily * 9-15 logreport

This fcrontab is fairly straightforward. First, we set some options: send mail
to feztaa (me), always send mail no matter what, and let me know if the command
was not run. Then, we run updatedb every day between 9 AM and 3 PM. Finally, we
run logreport at the same time that updatedb is run (logreport is just a quick
bash script I wrote to scan my logs and notify me of root logins).

In my own fcrontab, I have the following:

    !mailto(feztaa),mail(yes),forcemail(yes),noticenotrun(yes)
    %monthly * * 1-4 oldmail

This sets the same options as root's fcrontab, and then it runs oldmail as soon
as it can, some time during the first four days of every month (oldmail is
another simple script I wrote that simply archives and compresses my old mail).

What I've written here is by far no substitute for reading the man page; I've
barely scratched the surface in this hint. If you want to get the most out of
your fcron, do yourself a favour and read the man page.

To install your fcrontab, run:

##--CODE--##
fcrontab -u <user> -e
##--CODE--##

The -u option can be omitted if the fcrontab you want to edit belongs to the
same user who runs the command. The default editor (defined in /etc/fcron.conf)
should start with a blank screen. Type in your entries in accordance with the
fcrontab(5) man page.

When you're done, save and quit editing the file (:wq in vim). Fcrontab then
checks your work for errors, and it complains if it finds some. It will also
refuse to use the malformed fcrontab. If you get an error, try again, and read
the man page to see what you're doing wrong. When you get it right, fcrontab
passes the file to fcron and saves it in /var/lib/fcron/<username>. DO NOT EDIT
THIS FILE! Always use fcrontab to edit your fcrontab, it is much safer that
way.

10. Now, to control who has access to fcron, you edit /etc/fcron.allow and
fcron.deny. I think that only root and a select few priveleged users should be
able to use such a daemon, so I put "all" in fcron.deny and "root" and "feztaa"
in fron.allow.

11. We will now install the cronmail script that I talked about in the
introduction. If you do not want this script, you are now done! If you do want
it, read on...

First, run this as root:

##--CODE--##
cat >/usr/bin/cronmail <<"EOF"
#!/bin/bash
# $Id: fcrond-hint.txt,v 1.1 2003/09/13 16:18:12 tushar Exp $
# Author: Rob Park <rbpark@ualberta.ca>
# License: GNU General Public License

########################################################################
# You probably want to edit the following two variable definitions to  #
#            better match your system! You have been warned!!          #
########################################################################

# What is the default name to use if none is specified, or if root is
# specified? Basically, who gets root's mail?
default="feztaa"

# Where should the mail be delivered to? This is an mbox somewhere
# inside the user's home directory (sorry, only mbox format is supported
# as of now).
mbox="mail/cron"

###########################################################
# You shouldn't need to edit anything below this line! ;) #
###########################################################

# Throw away all the arguments until we find one that's a valid username
until id "$1" >/dev/null 2>&1
do
  shift
done

# The username is now the first argument
name="$1"

# If the first argument is missing, or "root", deliver it to the default
# user instead.
[ "$name" == "" ] && name=$default
[ "$name" == "root" ] && name=$default

# Pipe stdin to the mbox in the user's home folder, adding a few headers
# to make it look more like real mail.
formail -a "Message-ID:" -I "From: Cron <fcron@$HOSTNAME>" -I "To: $name <$name@$HOSTNAME>" >> /home/$name/$mbox
EOF
chmod 755 /usr/bin/cronmail
##--CODE--##

This script is a very simple sendmail replacement. It looks for a username in
the argument list, stamps some email headers onto the message with formail, and
then sends it off to an mbox in the user's home directory.  You can edit where
exactly you want it to be delivered, and who you want to get root's mail. Since
I get all my mail in ~/mail, I have the script deliver my mail to ~/mail/cron.

The next thing we need to do is tell fcron to use our cronmail script.  Run
this command to make the change:

##--CODE--##
cd /etc &&
perl -i -pe 's%^sendmail\s*=.*$%sendmail=/usr/bin/cronmail%' fcron.conf
##--CODE--##

Now restart fcron (if it is running), and you're all ready to go!

The End
-------

You're done! Now you have a scheduling utility that will run commands
automatically for you.

If you have any questions, suggestions, or problems, PLEASE email me and I will
help you to the best of my ability (note, don't email Lyle, he doesn't maintain
this anymore. Just email me, Rob).