In this article I am going to show you how to change the time on your Ubuntu machine using both the GUI and the command line. Hopefully, when you’re done with this, your computer clock will always be accurate.

Another option

Of course there is always another option. You can always set up NTP on your machine. I have already covered this in my article “Installing and configuring NTP on Linux“. That is, by far, the most reliable way to manage your clock. But when you don’t have constant access to the internet, or you simply don’t want to install a daemon on your machine – you have to resort to other methods. Let’s take a look at them here.

Command line

In order to set the date from the command line, you use the date command. The date command, however, is not the simplest command to figure out – at least not from the man page. If you look at the man page for date you see the time format uses a specific time string format like:

MMDDhhmmYYYY.ss

What the above string means is:

• MM is a two digit month, between 01 to 12.
• DD is a two digit day, between 01 and 31. NOTE: Regular rules for days, according to month and year, apply.
• hh is two digit hour, using the 24-hour period so it is between 00 and 23.
• mm is two digit minute, between 00 and 59.
• YYYY is the year; it can be two digit or four digit: your choice.
• ss is two digit seconds. The period (“.”) before the ss is necessary.

So, let’s say you want to set the correct date and time for this exact moment (the moment I am writing, not your reading). To do this I would enter the command:

sudo date 100507492010.00

at which point you would be returned:

Tue Oct 5 07:50:00 EDT 2010

GUI

Figure 1

Now, let’s take a look and see how this is done from the graphical front end. To do this click System > Administration > Time and Date. When you do this you will have to click the “lock” button to unlock this tool for changes. When you click this you will have to enter your sudo password. Upon proper authentication you will then be able to use the drop downs for hours, minutes, and seconds. When you change the time, you only need to close the tool, no saving required. NOTE: You can also change the date as well as the timezone with this same tool.

Final thoughts

Don’t be caught in the future or the past on Linux. Make sure your time is correct so you aren’t confusing those receiving your emails (unless you want them to think they are receiving emails from “future you”.)

The script made use of the following tools: date, cat, tar, mv, and rm. That’s it. The script will create backups with the date in the file name and then move the backups to a central location. Without further adieu, let’s get to the script.

#! /bin/sh

TMP=”/tmp/”

#Format the date in YEAR-MO-DY format
TODAY=`date +%F`

# Check to see if there is a lastbackup file in /tmp, if not create it,
# if so then set LAST equal to $TODAY
if [ -f /tmp/lastbackup ]; then
LAST=`cat /tmp/lastbackup`
else
LAST=$TODAY
fi

# Set the web directory backup name to the following
WEB_FILENAME=”inc-”$TODAY”-web.tar.gz”

# Set database backup name to the following
DB_FILENAME=”inc-”$TODAY”-db.tar.gz”

# this tars up my web directory into web.tar.gz tarball.
/bin/tar -czf $TMP$WEB_FILENAME –after-date=$LAST /var/www/html

# Move the web back to the backup directory
/bin/mv $TMP$WEB_FILENAME /data

# Remove web backup file from temp director
rm $TMP$WEB_FILENAME

# this tars up my database directory into $TODAY-db.tar.gz tarball.
/bin/tar -czf $TMP$DB_FILENAME –after-date=$LAST /var/lib/mysql

# Move the backup database to the backup directory
/bin/mv $TMP$DB_FILENAME /data

# Remove web backup file from temp directory
rm $TMP$DB_FILENAME

What I wanted this to do is create daily backups and move the backups to the /data directory on the drive housing the server. These backups will be saved for one month. After the month is completed i have a second script that deletes the months backups prior to running the next backup (so there is always a backup to fall to). How I made use of this script is simple. I save the script (called backup.sh) in the root user directory and create a second script called rm_backups.sh that looks like this:

#! /bin/sh

rm /data/*gz

With these two files in place I create two cron entries. The first cron entry is for running the backup.sh script and looks like:

0 23 * * *     ~/backup.sh

The second cron entry is for running the rm_backups.sh script and looks like:

0 20 1 * *     ~/rm_backups.sh

Both of the above cron jobs are created as the root user.

Final Thoughts

Naturally this solution could be easily modified (using such tools rsync) to set up an offsite backup solution. What should be obvious is that creating a simple, flexible server backup system on Linux is easy. With the help of a little ingenuity, you can create your own automated backup service.