Tech Pedia » Linux and Unix

Top Tweaks to Make Ubuntu Start-up Faster

Om — Wed, 03 Feb 2010 18:54:54 +0000

It is a general notion that Ubuntu is a bit sluggish; but here are some handy tips to trigger faster Ubuntu start-up

Boot-Up Manager

The Boot-Up Manager commonly abbreviated as BUM, happens to be a handy utility for starting or terminating boot-up scripts. After the installation is done successfully, BUM appears under — System -> Administration menu.

Using BUM Ubuntu’s start-up time may be reduced to a good extent.

Use Preload

Preload is a daemon process that helps in adaptive read-ahead functionality and monitoring various applications that are currently running so as to look for commonalities.

Depending upon the analysis, it preloads selective apps into the memory that are most commonly used. As a result, the start-up time is very low for commonly used applications, as they’ve already been fetched to the memory.

Use Openbox rather than Metacity

Openbox is a lightweight, minimalist version of the window manager that runs a lot faster than Metacity, which is lot bulkier, and hence slower. It has also been acclaimed that by running Openbox inside Gnome, the computer works faster and becomes cleaner.

To install Openbox, follow these steps:

sudo apt-get install openbox obconf openbox-themes

Next, you need to add an entry in start-up applications in order to set up Openbox as the default window manager. It can be done in following manner:

Go to System -> Preferences -> Startup Applications

Now, enter these details

Name: Openbox
Command: openbox –– replace

Note: As per Openbox documentation there are other ways of making Openbox your default window manager, though some of the functionalities are broken in 9.04, so the above steps are a safe work around for any version.

How To Use Windows Special Keys In Linux

Weston Campbell — Wed, 18 Nov 2009 17:14:25 +0000

Why are all the new keyboards sold with special Windows keys on them? How about making them do real keyboard functions while in X Window? Here is how.

First you need to find out which key mapping you are using. Usually it will be US, it might also be en_US, ca or else. Locate the file, usually in /usr/X11/lib/X11/xkb and edit it with your favorite editor. For me the file is called /usr/X11/lib/X11/xkb/symbols/ca.

The file lists all the key codes and what they do. The key codes for the Win95 special keys are LWIN, RWIN and MENU. All you need to do is add them to the list, with the functions for them. I decided to map the left WIN key to “@” and the right WIN key and MENU keys to “{” and “}”. Here are the lines I added:

key { [ braceleft ] };
key { [ at ] };
key
{ [ braceright ] };

By browsing the file you can find all the other symbols and what they do. You can also add multiple functions to a key, by using ALT and SHIFT.

The changes will take effect when you restart X Window. With the XKB extension (you do need to have it enabled in /etc/XF86Config btw) it’s easy to change the mapping of any key.

How To Detect Two Ethernet Cards in Linux

Weston Campbell — Sun, 15 Nov 2009 17:13:08 +0000

To configure an ethernet card in Linux, you need to enable it in the kernel. Then the kernel will detect your ethernet card if it is at a common IO port. But it will stop there, and will never check if you have 2 ethernet cards.

The trick is to tell the ethernet driver that there are 2 cards in the system. The following line will tell the kernel that there is an ethernet card at IRQ 10 and IO 0×300, and another one at IRQ 9 and IO 0×340:

ether=10,0×300,eth0 ether=9,0×340,eth1

You can add that line on bootup at the “boot:” prompt, or in the /etc/lilo.conf file. Don’t forget to run:

lilo

That will reload the lilo.conf file and enable changes.

What Is a Linux Distribution?

Weston Campbell — Thu, 22 Oct 2009 18:29:33 +0000

An operating system consists of a lot of files that perform a lot of different functions. And because there is no Linux Corporation to package and distribute the files that make up Linux, the task of getting Linux onto your computer in working order, along with the applications that you are likely to want, has fallen to a varied group of entities — companies, universities, user groups, and even private individuals. The Linux system and application collections they create are called distributions, or distros. You could bypass such distros and try to collect everything you’d need to set up a system all on your own, but you would undoubtedly lose your mind in the process. Most people, even the geekiest, opt for the distros.

The majority of these distros, whatever their ultimate target audience, basically consist of the same main elements: the Linux kernel itself, some sort of installer program to get all the system parts and applications properly installed on your machine, the X Window System to provide graphical interface support, one or more graphical desktop environments, and then a series of applications, such as word processors, audio players, games, and all the other files needed to make these things work.

There are, of course, a large number of distros. Some are geared to a specific audience, such as businesses, educators, gamers, students, programmers, system administrators, and specific language users. What makes each distro different is the specific software that is bundled with the Linux kernel, as well as other convenience features, such as the installer. Some distros are especially appropriate for home users due to their ease of installation. Mandrake, SuSE, and Fedora/Red Hat Linux are probably the three most popular in this regard, with Fedora/Red Hat Linux being cited as having the most users in the American market. While many of these entities charge for their distros, most also provide them free for download.

Basic Linux Commands

Abhinav Kaiser — Thu, 28 May 2009 04:58:29 +0000

Here’s a list of basic commands in Linux.

Courtesy : An ex-colleague.

An efficient UNIX shell-script…

Om — Wed, 22 Oct 2008 21:11:14 +0000

If you use lot of Unix shellscripts in the VI editor, then here’s an efficient UNIX shell-script to compare two files & delete one of them if they are duplicates… Simple yet pretty handy, just check-up!

if(test $# -eq 2)
then
if(test -f $1 && test -f $2)
then
if(cmp $1 $2)
then
echo “files are same”
echo “$2 deleted”
rm $2
else
echo “files are not same”
fi
else
echo “one of them is not a file”
fi
else
echo “MY COMMAND: enter two file names”
fi

Sounds pretty ordinary, but just check up is that really what you do as well?

And sure thing if have a better way then share it here :)

Picotux 100… Tablet PC? No it’s the world’s smallest desktop!!

Om — Fri, 22 Aug 2008 00:20:10 +0000

Well whether you call it small, tiny or microscopic depends only your perception of how small is small enough!! When we say small desktop PC it could possibly be something similar to Shuttles, or rather you can call them the Space Cube PC! But Picotux has redefined the word small with the introduction of Picotux 100 desktop computer!!

This amazing machine is based on Linux operating system and unbelievably measures hardly 35mm×19mm×19mm!!

So now what do you call it? Microscopic, tiny, baby!! well whatever it is… but that’s small for sure!! yeah.. :)

Specifications of this piece of gem are as follows:

• 32-bit ARM 7 Netsilicon NS7520 processor (55MHz)
• 2MB flash storage
• 8 MB SDRAM
• uClinux 2.4.27 Big Endian operating system

No official word on the price tag yet!!

Via [ Latest TechNews ] | [ Latest Gadget-Reviews ]

Linux & Unix Tricks

Abhinav Kaiser — Sun, 14 May 2006 04:34:17 +0000

A few linux tips and tricks for newbies. I have made this page as a reminder of tricks I used in Linux or unix along the way.

To expand a .tgz of tar.gz file in one line :

gunzip < file.tar.gz | tar xvf -
gunzip < file.tgz | tar xvf -

To change both group and ownership recursively :

chown -R someowner.somegroup file

To search the entire hardrive for a file in Linux :

find / -name somefilename

To search on Linux within each file for some phrase on the entire harddrive and display the file and line numbers :

find / -exec grep -n “phrase” ‘{}’ \; -print

Xargs can be used to create a list of input file to one of your perl scripts e.g.

ls *.txt | xargs ./your_perl_script

Wc can be used to print the total bytes, words and lines in a file, combined with cat you can print a total number of lines or byte, e.g. say you want the total number of lines in all files in the current directory ending in .txt.

cat *.txt | wc -l

Display a range of lines withing a file where the starting line number is x and the ending line number is y :

sed -n ‘x,yp’ filename

Vim uses A4 paper size by default to change this, use the following setting for letter size :

:set printoptions=paper:letter

Submitted by Tyler McGinnis

Some Unix Tricks

Abhinav Kaiser — Sun, 30 Apr 2006 13:51:19 +0000

These are some unix tips that might be helpful someday down the road. Feel free to contribute more unix tips by commenting on this article.

Becoming yourself from someone else’s login
su will retain the previous person’s environment, a good way to go from your ID to root
su – (note the dash) will read all your dot files and land you in your home, just like a real login

Core files
I assume hardly anyone looks at core files, but they are generated more often than we like and can be HUGE! On the top of your .cshrc add: limit coredumpsize 0k Remove any other lines that specify similar stuff. If there is a really hairy software problem, I will ask you to edit this line and deliver the ressulting core file to me, but it hasn’t happened yet.

You can also create a crontab for yourself to do some regular housekeeping for you:
On SUN:
setenv EDITOR vi
crontab -e
lands you in vi with your crontab file loaded, if one exists; get into append or insert mode and type:
# remove all my core files daily
05 23 * * * find ~ -name core -exec rm -f {} \;
Exit vi the usual way. This searches your home area for core files at 11:05 pm everyday and removes all of them.
On SGI: create a file with the above lines, then type: crontab This second method works on SUNs also.

Disk space
If there is not much space on your machine and you wonder why (and you know that you are not directly the culprit!): Check the /var partition for large files. (You may need to be root.) du -k /var (SunOS 4.1.x does not know the option -k!) It should be obvious in which directory very large files are hiding. Some machines have a /var/crash area that holds dumps from crashes. If research computing hasn’t requested them from you for inspection, these may go. Also, large LOG files may be truncated to conserve space. If you had any trouble recently check with me or someone knowledgeable before you remove any log info. If these files are large, there may be a good reason for it!

Cut and paste text files by columns
How many times have you wanted to edit those results files columnwise? Here’s a generic UNIX way: (startcol and endcol refer to character columns, including whitespace. Tab counts as 1.)
cut -cstartcol-endcol file {>receiving file} paste sourcefile1 sourcefile2 {>final file}
I like to preview and fine-tune my commands by looking at the result on standard out (the shell window) and then redirecting output to a (temporary) file when things look right. Those feeling really adventurous can combine things into a single command line…

File compression
Probably everyone is using compress to conserve disk space and/or net bandwidth. While compress has its merits, mainly that its efficient and available on nearly all UNIXes, it has NO consistency checks. And there are even more efficient tools today: Under /tsri/gnu/sun4/bin you’ll find gzip. Gzip and its companions gunzip, gzcat, gzmore, gzgrep (and so on) will work with files compressed with gzip, compress, pack and zip (the UNIX variant of PKZIP, perhaps it can handle PC files?). I have used gzip successfully for the last two years and SGI now ships it as part of their systems. That should speak for itself. Gzip compressed files end with .gz. To get at gzip, edit your .cshrc:

set path = ( /tsri/gnu/sun4/bin $path )
setenv MANPATH $MANPATH:/tsri/gnu/man
setenv GZIP “” (check gzip -h for available options)

On SGIs do nothing. gzip is already in your path.

Gzip can work through directory trees: gzip -r -9 will compress every file it find starting from downwards. The -9 switch specifies best compression at the expense of speed. Great for archiving.

For very efficient compression of some directory and its contents:
tar cvf – dir | gzip -9 > dir.tar.gz

To uncompress: gzcat dir.tar.gz | tar xvf -

Renaming a group of files
Suppose you have a group of files, named file_jan.1, file_jan.2, file_jan.3, etc. and you want to rename them to something like experiment_1_jan.txt, experiment_2_jan.txt, experiment_2_jan.txt, etc.

Use a script like this:

#!/bin/csh -f
foreach x ( file_jan.* )
mv $x experiment_$x:e_jan.txt
end

Submitted by : Stephen Jackson

11 Unix Tricks

Abhinav Kaiser — Sat, 11 Mar 2006 23:06:22 +0000

Whether you�re a newbie to Linux or you are a seasoned guru, you�re bound to find some scripts or programs which just make your life on the computer exponentially easier. The following is a list of them and explains what they do.

1. tac

tac is a command similar to cat, except that it reverses the output of the specified file.

tac

2. Multiple X-Sessions

Using multiple X-Sessions allows a user to have open more than just one instance of XFree, so multiple desktop environments can be used at a time.

startx — :

terminal name is simply which terminal X should start on. By default it starts on

0:0. If you want two open, you may want it open on 0:1, which can be run by:

startx — :1

The resulting desktops will exist on F7 – F12.

3. SSH

SSH is a telnet replacement which includes encryption for higher security.

ssh -l

is the name, specified in /etc/passwd, that you want to login as. Remove the -l for anonymous.

is simply the hostname or IP address of the computer to connect to.

4. links

links is a text based browser which has full support for tables

links

is simply the hostname or IP address of the computer to connect to.

5. Gkrellm

Gkrellm is a graphical application that displays system information in real-time. It displays everything from processor consumption to if new email exists in that specific

user�s inbox.

6. Keybindings

Keybindings allow a user to to run a certain program or command by hitting only a small keycombo.

In Sawfish, click on the Keybindings capplet and select your keybindings by adding a new one, selecting the command, and then select the desired keybinding.

7. more

more causes any info sent to the terminal after more than one page has been output. This allows the user to see a page at a time, taking their time on each page, without them having to worry about the text rolling off the screen.

more can be used as a straight program to view a file or can be piped to by any other applications

Note: an alternative to more is less

8. grep

grep is a command that allows the user to specify text to show on the screen and display only the line containing the quered string.

| grep string

9. wc

Utility to print basic formatting information about a file.

wc or wc can be piped to

10. find

A simple utility made to search your hard disk.

find

11. locate

A quick alternative to find

locate