‘tail’ can be used alone or can be combined with other commands like ‘grep’, ‘ls’ etc.

To use ‘tail’, let’s first create a text file. You can create the file by issuing following command in terminal;

touch my_file

Now open my_file with your favorite text editor (nano in my case) and write some lines. For this article, I have written the following 15 lines;

this is the 1st line
this is the 2nd line
this is the 3rd line
this is the 4th line
this is the 5th line
this is the 6th line
this is the 7th line
this is the 8th line
this is the 9th line
this is the 10th line
this is the 11th line
this is the 12th line
this is the 13th line
this is the 14th line
this is the 15th line

Now issue the following command in terminal;

tail my_file

It will print the last 10 lines which would be the “this is the 6th line” through “this is the 15th line”.

You can control the number of lines which ‘tail’ will print. You can either increase or decrease the number of lines. For example, if you want ‘tail’ to show only last 3 lines, you can do this by issuing the following command;

tail -n 3 my_file

Now it will print only last 3 lines. You can use any number of lines instead of 3. Or you can use a plus sign like;

tail -n+7 my_file

‘tail’ will start printing from 7th line to the end of the file.

You can view the desired file with respect to size. Issue the following command in terminal;

tail -c 14 my_file

And it will show the output of last 14 bytes. In my case, the output was;

the 15th line

‘tail’ not only displays the static output of a file but it can also monitor the file for changes. A ‘-f’ option is used with ‘tail’ and it starts acting like a monitoring tool which not only displays the last few lines but also constantly updates the output as the file changes. Here is a very popular example;

tail -f /var/log/message

‘tail’ will print the last 10 lines of ‘message’ file. If you now plug-in you USB stick, you will notice that the change in ‘message’ file will instantly be reported by ‘tail’. To release the cursor press Ctrl+c.

There are many other useful options which you can use with ‘tail’ like;

tail -q my_file        # never output headers

tail -v my_file        # always outputs headers

You can combine ‘tail’ with other utilities like ‘ls’, ‘grep’, ‘head’ etc.

You can combine ‘tail’ with ‘grep’ to get lines with some specific ‘word’.

tail -n 5 my_file | grep 14

It will print only those lines out of last 5 which contains the word ’14′. In my case the output was:

this is 14th line # ’14′ will be highlighted

‘tail’ can also be combined with ‘ls’ to get the list of last few files/folders. For example, if you issue the following command;

ls -l | tail -n 2

It will give a long listing of files/folders but will show the last 2 entries of the working directory.

These are just two examples of combining ‘tail’ with other utilities. There are countless examples of combination of ‘tail’ and other softwares.

‘GNU tail’ is a very handy tool. It can output any amount of data depending upon the options used. It makes the work of an ordinary user much easer and helps him/her find information in files more efficiently. To become an expert in Linux, this is a mandatory utility over which a user must have complete mastery. Hopefully, this tutorial gets you started chasing your tail!

Chasing Your ‘Tail’ With Linux originally appeared on Yet Another Linux Blog on January 27, 2011.

You may be thinking about some way to avoid typing commands over and over. Enter the ‘alias’.

The ‘alias’ tool is a way to make the complicated things simple (and simple things simpler). You can use ‘alias’ instead of long (or even short) commands.  Now let’s see how the ‘alias’ works.

‘alias’ can make difficult and lengthy commands easy. The general format of ‘alias’ is:

alias Any_Word=”Command”

It means you linked an existing command to a (New) Word. This ‘Any_Word’ may contain anything – any alpha-numeric symbol, ‘Any_Word’ as well as ‘Command’ are interchangeable and can be used for the same purpose.

Simple Commands Made Simpler

As an example, ‘ls -l’  is used for listing directory contents in ‘long listing format’. This ‘ls -l’ can be replaced with a simpler alias. You can set the ‘alias’ for ‘ls –l’ as follows:

alias ll=”ls –l”

Now you just have to type ‘ll’ (without quotes) to get ‘long listing format’.

Or if you frequently misspell ‘ls’ as ‘sl’ and don’t want to install ‘sl’ package, then, you can use the following alias:

alias sl=”ls”

Now, whenever you type ‘sl’ in terminal, it will give you same results as ‘ls’.

Now consider even simpler example. To close a Terminal (or logout), you have to type ‘exit’ in Terminal. This ‘exit’ command can be made even simpler by using the following ‘alias’:

alias x="exit"

Now, you only have to type ‘x’ in Terminal to ‘exit’

Other examples of ‘alias’ are:

alias cp="cp -iv"
#make copy operation interactive and verbose

alias rm="rm -iv"
#make remove operation interactive and verbose

alias mv="mv -iv"
#make move operation interactive and verbose

Make Package Management A Bit Simpler

If you use Debian (or its derivatives) then you will be familiar with APT.  It is an excellent package manager.

In Ubuntu, to install software using APT, you have to use the following command:

sudo apt-get install <sofware_name>

It is a long command and consumes a lot of your time and energy

You can shorten this command by using ‘alias’.  Issue the following command in Terminal:

alias Install=”sudo apt-get install”

You can obviously use your own word instead of ‘Install’.

Now, you just have to type:

Install <software_name>

to install the (same) software. Simple, isn’t it?

You can simplify other aspects of APT. For example, you can use the following ‘alias’:

alias Remove=”sudo apt-get remove”

to uninstall a software.

Some other examples of attaching APT with ‘alias’ are:

alias Update=”sudo apt-get update”

alias Upgrade=”sudo apt-get upgrade”

alias Search=”apt-cache search”

alias Autoremove=”sudo apt-get autoremove”

alias Autoclean=”sudo apt-get autoclean”

alias Purge=”sudo apt-get remove –purge”

and so on…

A Very Interesting ‘alias’ For A Difficult Keyboard Button

On some keyboards, the dot (.) button is at very difficult position and if you have to use it more than once, it becomes even more difficult.  That’s why ‘cd ..’ is the command which I mistype the most.  This complication can be easily removed by using following ‘alias’ (you can use any other word instead of a dot):

alias .=”cd ..”

alias ..=”cd ../..”

alias ...=”cd ../../..”

alias ....=”cd ../../../..”

Using Internet From Terminal

If you regularly use lynx to browse the internet in terminal then you have to type long urls with lynx to visit the web pages.  You can simplify these long urls by using ‘alias’:

alias Google=”lynx http://www.google.com/”

alias Yahoo=”lynx http://www.yahoo.com/”

alias yalb =”lynx http://linux-blog.org/”

and so on…

Now just type Google, Yahoo or yalb to visit the respective web sites.

Simple ‘alias’ For More Complicated Commands

Long commands are not only difficult to remember but also take more time to type; when you have to use them on daily basis, you become frustrated when typing them again and again and again… So, ‘alias’ are more suitable for long and complicated commands.

Let’s consider an example.

To find the top 10 largest files in your system, you can set the following ‘alias’:

alias top10files=”find . -type f -exec ls -sh {} \; | sort -n -r | head -10”

You can even mix different commands with ‘alias’.  For instance, if you regularly use ‘tail’ and direct its output to file to later view that file, you can set a very simple ‘alias’ to do this cumbersome operation in 1 word:

alias Tail=”tail /var/log/messages > hello.txt;cat hello.txt”

Now just enter ‘Tail’ and viola! All is done at once.

You can use any file with tail and direct its output and you can even use ‘nano’ or ‘vi’ to view/edit its output.

Here’s another example… ‘alias’ to connect to a remote server:

alias any_name=”ssh <remote_server_address> -l <username> -p <port>”

You can even create ‘alias’ for your bash scripts, like:

alias clc=”sh /home/user/myscripts/calc.sh”

Now that you have set a few different ‘alias’  you might want to check that which ‘alias’ are set on your system.  To do that, just issue the following command:

alias

and it will list all the set ‘alias’ you have.

To remove an ‘alias’, just issue the ‘unalias’ command, like:

unalias Google

and now typing Google in terminal will do nothing (as it was set with lynx).

To remove all the ‘alias’, issue the following command and all the ‘alias’ are gone:

unalias –a

We have discussed the way of setting the ‘alias’ for different kinds of commands.  But setting ‘alias’ in this way be temporary.  When you reboot you PC, all the ‘alias’ which you have set will be gone.  This does not mean that you have to set all the ‘alias’ every time you boot your PC.  If you have set an ‘alias’ and you liked it so much that you want it to permanently reside in you PC, just add this alias in ‘.bashrc’ file in you home directory. For example, if you want ‘alias’:

Install <software_name>

to permanently reside in your PC then user your favorite text editor and add the following line in your ‘~/.bashrc’ file:

alias Install=”sudo apt-get install”

Now this ‘alias’ will not vanish into thin air when you reboot your PC. Only those ‘alias’  which are listed in ‘~/.bashrc’ file will be permanent.

This guide is just a preview about ‘alias’.  It is just about basic ways of using ‘alias’ to make your life simpler.  ‘GNU alias’ is a tool which can simplify your life immensely.  But unfortunately this tool is not given the attention it deserves.  In short, it is such a powerful tool that if you give it proper time, it can make you forget typing

Using ‘Alias’ in Linux originally appeared on Yet Another Linux Blog on December 23, 2010.

• Compaq Armada E500 Laptop
• 700MHz Intel Pentium III
• 256MB PC133 SDRAM
• ATi Rage Mobility
• Intel Ethernet Pro 100
• Toshiba 10GB Hard Disk
• Netgear WG511 Wireless PCMCIA Card

Installation

I chose to use a network install via HTTP. This went quite smoothly, initially via a text interface for configuring the network and entering the address to install from, then a graphical interface for partitioning and package selection. Right from the start Fedora looks like a professional O/S, it’s not fluffy and cute, but it is very pleasant to look at. Partitioning was handled automatically by Disk Druid, no problems at this stage.

Fedora offers 4 options for package configuration; Personal Desktop, Server, Workstation and Custom. I chose a custom install as I wanted to install KDE 3.4 as well as the default GNOME desktop. I didn’t feel that package selection was a good as my usual distro (Mandriva). When selecting packages in Mandriva (or previously Mandrake) removing a package in one category meant the package would not be installed and that any other packages that were no longer needed would also not be installed. With Fedora it would appear that packages may appear under more than one category and therefore may be installed if you remove them from your selection in one category and not in another. This doesn’t bother me too much, but if you really wanted to make sure a package was not installed then you may find this frustrating.

All my hardware was detected fine bar two items. The first I’m not too worried about as only the latest version of Mandriva has allowed me to use it, and that’s the wireless network card. Mandriva offers the option to use NDISWrapper during the install, but more about that in another review The second item was the monitor, but this was resolved simply by choosing a generic monitor capable of 1024×768 (before doing this I could only select 800×600). Once again, this really didn’t bother me and I don’t believe it would have caused anyone adept enough to attempt an O/S installation any problems.

First Boot and Beyond

Fedora Core 4 has a very nice graphical boot display, it’s not a necessity but it’s certainly a nice touch. The GDM theme is very pleasant and professional looking. Logging in takes a while, but that would probably be improved by running it on something a bit quicker!

The GNOME desktop is pleasant, easy on the eye and uncluttered. I’m usually a KDE user but I like the idea of using two bars. The bottom bar shows open programs, a view desktop button and the Workspace Switcher. The top bar has the menus, shortcuts, clock, volume control and battery monitor. There’s also an Up2date button that monitors available updates. So far, there’s none available so it’s not a feature I’ve been able to test.

The menu structure is good, I like a menu that’s not cluttered and Fedora have managed to organise everything into only 6 headings. OpenOffice.org, Firefox and Evolution are all available as shortcuts on the top bar, I can’t imagine these aren’t the most commonly used applications for many people and they’re always removable if necessary. Also available on the top bar is a Desktop menu where you can change desktop settings, lock the screen or log out. I’m not sure if it’s a GNOME desktop thing or it’s something Fedora have added themselves, but there’s also a Places menu. This allows easy network browsing and access to your own files and mounted network shares.

The network is all set up and ready to go, I can get my email and surf the web without having to configure anything else (other than my account settings of course). I’ve heard plenty about Fedora’s lack of multi-media capabilities out-of-the-box, I don’t see it as a big problem as you only have to add them once. Flash and Java are easy enough to install for anyone familiar with Linux and certainly doesn’t take long; very few distros install these by default so I don’t see it as something to complain about. Not being able to play MP3s is a little unusual, but only required installing plugins for whichever application you prefer. Once this is done it’s on a par with other distributions.

Fedora happily mounted my USB flash drive and put a helpful icon on the desktop, this was done consistently and without user intervention. It also did this for CD’s so I was happy with the desktops’ behaviour as far as removable media goes.

All in all I’m very pleased with this latest incarnation of Fedora but I think what it really lacks is a Mandriva or SUSE style central configuration tool. I’m very fond of being able to control everything from one place rather than having to hunt through menus for various applications to configure different parts of the system.
Next Up: SUSE 10.0

Apostasy

Linux-Blog Editors Note: Fedora Core 5 is due out February 2006. We’ll have Apostasy take another look at things then and see if Fedora Core has improved any for him.

New Linux with an Old Laptop: Fedora Core 4 originally appeared on Yet Another Linux Blog on October 24, 2005.

My first Linux experiences came through Knoppix and Mandrake, which send you to the KDE desktop by default. I used KDE at first, but I wanted to experiment with other less Windowsesque environments. The first one I installed was Enlightenment 16, which I must confess I had first heard of in Neal Stephenson’s essay “In The Beginning There Was the Command Line.” In that essay he said Enlightenment “may be the hippest single technology product I have ever seen” and that “it looks amazingly cool.” Since these sentiments were written in 1999, plenty of rivals have emerged for the title of “hippest tech.”

Once I had Enlightenment installed on my laptop there was no going back. I tried out a few other window managers, but the efficiency of E16 was hard to beat. My only complaints were that Enlightenment seemed a bit short on conveniences such as launchers, so I ended up running GNOME stripped down to one panel and the main menu with E16 as the window manager. Meanwhile, I read the descriptions of the new “desktop shell” that the Enlightenment crew was working on, dubbed Enlightenment DR17 (or E17, as I’ll refer to it from here on) and thought it sounded like exactly what I wanted.

I should mention that “window manager” isn’t quite the right term for E17. The developers call it a desktop shell, intending it to fill in the space between a simple window manager like the original Enlightenment and a full-featured desktop environment like GNOME. In other words, they were setting out to create a desktop not unlike my own E16/GNOME hybrid. In this respect it does not disappoint.

In creating E17 the Enlightenment crew have created a set of shared libraries (the Enlightenment Foundation Libraries) with the goal of building a complete set of applications to create an integrated environment where all files and programs are readily available that remains fast and non-resource-intensive. Essentially, E17 breaks down a desktop environment into its essential components (window manager, file manager, launcher, main menu, etc.) and offers them as a completely customizable package, where the user chooses which elements to use at any time.

Early Impressions

When I started using E17 back in early May, I had already been a regular user of E16 for a while. My first impressions were that E17 sported some neat features, but configuring the menus (by making all those damn eapp files, E17′s special icon format — read on for more details) was a hassle, plus E17 was missing many of the small features, such as edge-flipping or icon boxes, that I liked in E16. But I stuck

run command

with it, updating it on a regular basis and reading the continually updated user guide at Get-E.org, and usability has steadily increased. Also, a number of the features I had been missing were added (like

window list

edge-flipping) or had been there all along (turns out there is an icon box module called ibox, which is disabled by default). A graphical eap creator and other additions like a run command, alt-tab window switching (complete with a well designed display) and, for those who use sloppy or mouse focus, automatic placement of the cursor in the newly selected window have improved general usability.

Peeves

One functional feature of E16 I still miss is using middle-clicks to shade windows. I made an attempt at setting this mouse binding in E17, though what happened was middle-clicking anywhere in the window (as opposed to directly on the titlebar) would shade it, which is problematic when, say, browsing in Firefox and trying to open links in new tabs by middle clicking.

Naturally I wasn’t expecting everything to work perfectly — even the splash screen advises “This is development code — be warned!” But to paraphrase someone from another forum, E17 is more stable than your average development window manager.

One early issue I had was Firefox behaving strangely with sloppy focus, the default setting. The titlebar would flash in time with my typing, I would lose all of my Firefox-specific keyboard shortcuts, and there would be no auto completion in the URL bar. Perhaps one of the many “minor bugfixes” one reads about in CVS logs took care of it. Another recently remedied problem was the inability to open menus in applications run under WINE. Another curious effect with WINE programs is that any Windows apps opened with WINE (or CrossOver) have the same window-class, which is how Enlightenment chooses what eap icon it uses to represent the app in the taskbar, pager, and window list. While you can set up different eaps with unique icons for each application (useful for the menu), they will all appear with the same icon in the pager (not so useful). Annoying, though likely not a deal breaker for most users.

Other minor annoyances:

• no easy configuration of module appearance
• click-to-raise only works on titlebar under mouse/sloppy focus, while click-to-focus works anywhere in the window.

Good Things

Evidence in icon view with shelf displayed

I remember someone writing that one of the biggest considerations in your choice of an OS or window manager was answering the question, “Does this help you get your work done?” For a short time last month I switched back to Fluxbox, as I found minor things like focus issues distracting while trying to work. But while writing this review, I’ve found that those minor issues are either fixed or there are workarounds, and E17 has become my standard desktop again. I recently loaded up E16 on the home computer and was struck by how inelegant it is compared to E17.
And so I have stayed with the new Enlightenment. Bugs are fixed, people are creating new themes and icon sets, the user guide at Get-E is becoming ever more detailed, and of course, since this is Linux, there are plenty of opportunities for users to join in and make the damn thing better still.

Installation

As far as installation goes, you can manually configure, compile, and install following the directions at Enlightenment.freedesktop.org, or you can avail yourself of a few less labor intensive options. Packages are available for Debian, rpms for Fedora, and ebuilds (both snapshots and CVS) in portage for Gentoo. More information on installation can be found here. I use both the Fedora rpms and Gentoo ebuilds (from CVS). At the rate E17 is updated, last month’s version is already rustic. I tend to update it every other week. Thus far, I have had no upgrades leave me with an unstable or unusable E17.

The Strange and Wondrous World of the EAP

The only major hurdle facing a new user of E17 is the creation of eap files, which are essentially small files consisting of an icon plus basic information about a program,

The ibar launcher

including its name and executable. In a desktop environment like GNOME, you create launchers on the panel by choosing an icon and entering the program’s name and executable in the launcher

eap editor

Fortunately, it is easily done with an included script or using a guicreation tool. Creating an eap is a similar process, but newly created eaps are stored for Enlightenment to use in the menus, launchers, icon boxes, taskbars, and pagers. Though a few eaps

menu editor

are included in the basic installation, you will want to create more. included in the e_utils package. Ideally, you should only have to build a set of eaps once, plus a number of prebuilt eap collections are available online at www.get-e.org. You then organize menus and launchers by editing text files or using the graphical tool Entangle.

background chooser

Additional configuration is done with the main menu , the background chooser Emblem or the command line tool enlightenment_remote, which is by far the most powerful of the configuration tools available in E17. With it you can set backgrounds, themes, focus policy, virtual desktops, modules, mouse button bindings, key bindings, fonts, menu display speeds, edge-flipping, and more. Graphical tools for key bindings, background creation, and general configuration are all on the TODO list, along with items like desktop icons, tabbed windows, and other monitor modules, so there are plenty of opportunities for coders looking to get involved.

Themes and backgrounds also have their own unique file format that allows a file to include multiple images and scripts, which makes some fun effects possible, such as title bar animation during focus changes, light effects in backgrounds and full-screen animations. A number of themes and backgrounds are available at www.get-e.org. Static backgrounds can be generated from any normal image file.

The following is a short flash video demonstrating a few of the animated backgrounds available, as well as one of the desktop switching animations.
(Go Watch the Background Video!)

The one nasty little surprise that often awaits a user after an upgrade that is your configuration is reset. What this means is that your module, theme, background, and key binding settings are all lost, though these can be easily restored by writing a simple script. Also, as development progresses, E has become better at remembering some settings (menus, weather url, module placement, startup programs, etc.), which makes for less work to restore your desktop. Eap files, menus, and launcher configurations are not affected by updates.

Modules

A central feature of the E17 desktop is the collection of modules which can be added or removed as the user wishes, allowing Enlightenment to be as light or heavy as one desires. Currently there are 16 official modules available, ranging from the useful (pager, launch bar) to the informative (cpu/memory monitor, weather) to eye candy (dropshadow, flame, snow). Discovering the modules was a bit of an adventure, as there was no obvious way to list all available choices, only the loaded ones. (By the way, you can find all the available modules – in Gentoo anyway – by looking in /usr/lib/enlightenment/modules/ and /usr/lib/enlightenment/modules_extra/)

The following three flash videos show off the various modules in use:

• Basic modules
• Flame
• Snow

Evidence

icon view

Another new EFL application, though not actually a part of E17, but deserving of

browser view

special mention is Evidence, essentially an graphical file browser, though a bit more flexible than say, Nautilus. It offers a choice of views (icon, browser, or tree), customizable context menus, and a command shell. The context menu includes options for various file types, such as opening image files in Entice (the E17 image viewer) or editing ID3 tags on mp3 files. Also, you can use the shelf (a frame at the bottom of the main window) to store often used files or application launchers. Evidence can also be used to draw the desktop.

tree view

Personally, this is one of my favorite new applications, even though I have yet to

command shell

master half of what it can do. The command shell combined with the icon view gives me what feels like the best of both the terminal (powerful commands like cp and mv) and graphical file managers (excellent visual organization). There are little tricks to be learned (like using the full path of a file name in shell commands — tab completion can be used for this), and occasional bugs (like the vanishing configuration window), but considering that Evidence has become

editing mp3 tags

remarkably more stable and functional in the past month alone, I foresee this become my full time file manager.
You can use Evidence in any window manager. Visit the Evidence home page for more information.

Engage and Other Applications

Possibly the most popular of the new EFL applications, or at least the one asked about most frequently on various forums, Engage is a combination app launch bar, taskbar, and system tray similar to the dock in Mac’s OS X. Engage is available in two different forms: a standalone form which can be used with any window manager or a module form for use with E17. The standalone version is a bit more robust and configurable than the module form, but I have been using Engage in place of the iBar launcher recently without any troubles, and having the system tray available was quite useful in creating the Wink movies for this review.

Entice

A number of other applications are being developed as well. Equate is a simple, themeable calculator, Entice is an excellent image viewer that allows for zooming and slide shows, Elation is a bare-bones media player, and Eclair is a music player with playlist support, similar to XMMS. Though these new EFL apps are worth keeping an eye on as development progresses, Entice is the only one I use on a regular basis.

On the whole, I am very happy with the new Enlightenment. On their homepage (www.enlightenment.org), the Enlightenment team states “We believe your desktop should not be an eyesore. It should be functional AND beautiful.” They are doing well on both fronts.

Misunderstruck

Enlightenment 17 Review originally appeared on Yet Another Linux Blog on August 22, 2005.