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Automatic Package Updates Using cron-apt

The package cron-apt is designed to automatically update the package list and download upgraded packages. Therefore it basically calls the commands

apt-get update

and

apt-get dist-upgrade -d

.

Installing Cron-apt

You can get cron-apt from the Universe Repositories.

Making cron-apt execute regularly

To make cron-apt be executed regularly, create a link in /etc/cron.daily or /etc/cron.weekly with

sudo ln -s /usr/sbin/cron-apt /etc/cron.daily/

.

Cron-apt only downloads new packages, to install them you need to execute

sudo apt-get dist-upgrade

manually.

• When using cron-apt you do not have to follow the steps below.

Automatic Weekly Package Updates Using Cron And Apt-Get

WARNING: As with any system changes, the potential for creating new or additional problems may occur. Please be sure to backup your data and configurations! Use this document at your own risk. Keeping your Ubuntu (or Debian based) system packages regularly updated not only helps to better secure your system, but also helps keep it running bug free. This howto discusses how to setup a very easy and simple Cron job on your system that will update your system packages weekly, and remove any old unused packages no longer installed after updating. (This document assumes an always or mostly always on system with a broadband, not dial-up, Internet connection.)

Creating the Weekly Cron Job File

First you will need to create the cron job file. You can use a simple text editor to create the file and save it in your home directory. In Ubuntu, open Applications > Accessories > Text Editor. In the Text Editor, type the following lines:

 #!/bin/bash
apt-get update
apt-get upgrade -y
apt-get autoclean

Now click Save and name the file something like "autoupdt". The default directory should be your home directory, but verify to be certain. (The steps following this will assume the file has been saved in your home directory.)

Moving the Cron Job File to Cron.Weekly

Now that you have created the cron job file, it needs to be moved into the weekly cron directory so that it will be run automatically on a weekly basis. To do this, we first need to open a command line terminal. In Ubuntu, click Applications > System Tools > Terminal. Now you should see your terminal prompt. At the prompt type "ls" and press Enter (or Return on some keyboards). In the list you should see your newly created file "autoupdt".

user@system:~$cd ~
user@system:~$ls

Now that we know the file is there, we need to move the file to the proper directory. Type the following command at the command line promt to move the file:

user@system:~$sudo mv autoupdt /etc/cron.weekly

(You may be prompted to enter your sudo password, which is YOUR password.) Now we need to move to the Cron directory to verify the file was moved. At the command line prompt type:

user@system:~$cd /etc/cron.weekly
user@system:~$ls

You should see the "autoupdt" file in the list. (If not, try the previous move command again.)

Making the Cron Job File Executable

Now that the file is created and ready to be run weekly by cron, we still need to make the file executable in order for cron to be able to run it. Since you are already in the cron.weekly directory, all you need to do is enter this command at the prompt:

user@system:~$sudo chmod 755 autoupdt

(Again you may be prompted for your sudo password.)

Finished

Now that the file is executable, you are finished. The cron job will run weekly and update your source list (to see if there are any new package updates), update your packages as found and needed, then clean out any old unused no longer installed packages. You can still update using Synaptic Package Manager or apt-get at the command line, but now you can relax a bit knowing your system will be updated automatically on a weekly basis.

Alternatively: Package Updates with Logging using Aptitude

Apt-get doesn't write details of changes it makes to log files. Aptitude logs to /var/log/aptitude, and can mail a report to root, which can be redirected to the sudo user if Postfix is set up to do this. As with the examples above, create this script as /etc/cron.weekly/autoupdt and make it executable. We use here a special action of aptitude called 'full-upgrade' (which will always upgrade your packages to the latest version, before Ubuntu 7.10 it was called 'dist-upgrade'). However, you might want to have a more conservative action when doing this on a server, the action 'safe-upgrade' is there for you. You can check the guide on aptitude for more information: AptitudeSurvivalGuide.

#!/bin/bash

tmpfile=$(mktemp)

echo "aptitude update" >> ${tmpfile}
aptitude update >> ${tmpfile} 2>&1
echo "" >> ${tmpfile}
echo "aptitude full-upgrade" >> ${tmpfile}
aptitude -y full-upgrade >> ${tmpfile} 2>&1
echo "" >> ${tmpfile}
echo "aptitude clean" >> ${tmpfile}
aptitude clean >> ${tmpfile} 2>&1

mail -s "Aptitude cron $(date)" root < ${tmpfile}
rm -f ${tmpfile} 

Here is a script (based on the above) that is useful if you don't have sendmail or postfix installed on your computer. It collects all the output from aptitude and manually sends an email using a mail server you specify. You must also specify the recipient of the email. As with the examples above, create this script as /etc/cron.weekly/autoupdt and make it executable:

#!/bin/bash
#
# use aptitude to automatically install updates. log and email any
# changes.
#

#
# variables to change
#

# address to send results to
[email protected]
# host name of smtp server
MAIL=mail.yourisp.com


#
# script is below here (do not change)
#

tmpfile=$(mktemp)

#
# smtp setup commands
#

echo "helo $(hostname)" >> ${tmpfile}
echo "mail from: root@$(hostname)" >> ${tmpfile}
echo "rcpt to: $MAILTO" >> ${tmpfile}
echo 'data'>> ${tmpfile}
echo "subject: Aptitude cron $(date)" >> ${tmpfile}

#
# actually run aptitude to do the updates, logging its output
#

echo "aptitude update" >> ${tmpfile}
aptitude update >> ${tmpfile} 2>&1
echo "" >> ${tmpfile}
echo "aptitude full-upgrade" >> ${tmpfile}
aptitude -y full-upgrade >> ${tmpfile} 2>&1
echo "" >> ${tmpfile}
echo "aptitude clean" >> ${tmpfile}
aptitude clean >> ${tmpfile} 2>&1

#
# i get a lot of escaped new lines in my output. so the following
# removes them. this could be greatly improved

tmpfile2=$(mktemp)
cat ${tmpfile} | sed 's/\r\r/\n/g'|sed 's/\r//g' > ${tmpfile2}
mv ${tmpfile2} ${tmpfile}

#
# smtp close commands
#

echo >> ${tmpfile}
echo '.' >> ${tmpfile}
echo 'quit' >> ${tmpfile}
echo >> ${tmpfile}

#
# now send the email (and ignore output)
#

telnet $MAIL 25 < ${tmpfile} > /dev/null 2> /dev/null

#
# and remove temp files
#

rm -f ${tmpfile}

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