Linux tips every geek should know

Linux tips every geek should know

What separates average Linux Users from the Super-Geeks? Simple; Years spent learning the kinds of hacks, tricks, tips and techniques that turn long jobs into a moment’s work. If you want to get up to speed without having to put in all that leg-work, we’ve rounded up over 10 easy-to-learn Linux tips to help you work smarter and get the most from your computer in our part series on: Linux tips every geek should know. Enjoy!

#1: Check processes not run by you
Difficulty: Expert

Application: bash

Imagine the scene – you get yourself ready for a quick round of Crack Attack against a colleague at the office, only to find the game drags to a halt just as you’re about to beat your uppity subordinate – what could be happening to make your machine so slow? It must be some of those other users, stealing your precious CPU time with their scientific experiments, webservers or other weird, geeky things!

OK, let’s list all the processes on the box not being run by you!

ps aux | grep -v `whoami`

Or, to be a little more clever, why not just list the top ten time-wasters:

ps aux  --sort=-%cpu | grep -m 11 -v `whoami`

It is probably best to run this as root, as this will filter out most of the vital background processes. Now that you have the information, you could just kill their processes, but much more dastardly is to run xeyes on their desktop. Repeatedly!

#2: Replacing same text in multiple files
Difficulty: Intermediate

Application: find/Perl

If you have text you want to replace in multiple locations, there are several ways to do this. To replace the text Windows with Linux in all files in current directory called test[something] you can run this:

perl -i -pe 's/Windows/Linux/;' test*

To replace the text Windows with Linux in all text files in current directory and down you can run this:

find . -name '*.txt' -print | xargs perl -pi -e's/Windows/Linux/ig' *.txt

Or if you prefer this will also work, but only on regular files:

find -type f -name '*.txt' -print0 | xargs --null perl -pi -e 's/Windows/Linux/'

Saves a lot of time and has a high guru rating!

#3: Fix a wonky terminal
Difficulty: Easy

Application: bash

We’ve all done it – accidentally used less or cat to list a file, and ended up viewing binary instead. This usually involves all sorts of control codes that can easily screw up your terminal display. There will be beeping. There will be funny characters. There will be odd colour combinations. At the end of it, your font will be replaced with hieroglyphics and you don’t know what to do. Well, bash is obviously still working, but you just can’t read what’s actually going on! Send the terminal an initialisation command: reset and all will be well again.

#4: Creating Mozilla keywords
Difficulty: Easy

Application: Firefox/Mozilla

A useful feature in Konqueror is the ability to type gg onion to do a Google search based on the word onion. The same kind of functionality can be achieved in Mozilla by first clicking on Bookmarks>Manage Bookmarks and then Add a New Bookmark. Add the URL as:

http://www.google.com/search?q=%s

Now select the entry in the bookmark editor and click the Properties button. Now enter the keyword as gg (or this can be anything you choose) and the process is complete. The %s in the URL will be replaced with the text after the keyword. You can apply this hack to other kinds of sites that rely on you passing information on the URL.

Alternatively, right-click on a search field and select the menu option “Add a Keyword for this Search…”. The subsequent dialog will allow you to specify the keyword to use.

#5: Running multiple X sessions
Difficulty: Easy

Application: X

If you share your Linux box with someone and you are sick of continually logging in and out, you may be relieved to know that this is not really needed. Assuming that your computer starts in graphical mode (runlevel 5), by simultaneously pressing the keys Control+Alt+F1 – you will get a login prompt. Insert your login and password and then execute:

startx -- :1

to get into your graphical environment. To go back to the previous user session, press Ctrl+Alt+F7, while to get yours back press Ctrl+Alt+F8.
You can repeat this trick: the keys F1 to F6 identify six console sessions, while F7 to F12 identify six X sessions. Caveat: although this is true in most cases, different distributions can implement this feature in a different way.

#6: Faster browsing
Difficulty: Easy

Application: KDE

In KDE, a little-known but useful option exists to speed up your web browsing experience. Start the KDE Control Center and choose System > KDE performance from the sidebar. You can now select to preload Konqueror instances. Effectively, this means that Konqueror is run on startup, but kept hidden until you try to use it. When you do, it pops up almost instantaneously. Bonus! And if you’re looking for more KDE tips, make sure you check out our article, 20 all-new KDE 4.2 tips.

#7: Backup your website easily
Difficulty: Easy

Application: Backups

If you want to back up a directory on a computer and only copy changed files to the backup computer instead of everything with each backup, you can use the rsync tool to do this. You will need an account on the remote computer that you are backing up from. Here is the command:

rsync -vare ssh jono@192.168.0.2:/home/jono/importantfiles/* /home/jono/backup/

Here we are backing up all of the files in /home/jono/importantfiles/ on 192.168.0.2 to /home/jono/backup on the current machine.

#8: Keeping your clock in time
Difficulty: Easy

Application: NTP

If you find that the clock on your computer seems to wander off the time, you can make use of a special NTP tool to ensure that you are always synchronised with the kind of accuracy that only people that wear white coats get excited about. You will need to install the ntpdate tool that is often included in the NTP package, and then you can synchronise with an NTP server:

ntpdate ntp.blueyonder.co.uk

A list of suitable NTP servers is available at www.eecis.udel.edu/~mills/ntp/clock1b.html. If you modify your boot process and scripts to include this command you can ensure that you are perfectly in time whenever you boot your computer. You could also run a cron job to update the time.

#9: Finding the biggest files
Difficulty: Easy

Application: Shell

A common problem with computers is when you have a number of large files (such as audio/video clips) that you may want to get rid of. You can find the biggest files in the current directory with:

ls -lSrh

The “r” causes the large files to be listed at the end and the “h” gives human readable output (MB and such). You could also search for the biggest MP3/MPEGs:

ls -lSrh *.mp*

You can also look for the largest directories with:

du -kx | egrep -v "\./.+/" | sort -n

#10: Nautilus shortcuts
Difficulty: Easy

Application: Nautilus

Although most file managers these days are designed to be used with the mouse, it’s also useful to be able to use the keyboard sometimes. Nautilus has a few keyboard shortcuts that can have you flying through files:

Open a location - Ctrl+L
Open Parent folder - Ctrl+Up

Arrow keys navigate around current folder.
You can also customise the file icons with ’emblems’. These are little graphical overlays that can be applied to individual files or groups. Open the Edit > Backgrounds and Emblems menu item, and drag-and-drop the images you want.

Hope that moved you up the grid.
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