Ubuntu For Free » Shell

My current screenrc file

admin — Thu, 04 Mar 2010 01:01:33 +0000

Since it was requested, below are the contents of my current .screenrc file for use with GNU screen. It’s got a hardstatus and a caption. I like it simple, but high contrast so that I don’t have to squint to see what it says, hence the bright colors. Feel free to customize and provide some feedback.

caption always '%{= Yk}%l%{= bW}%-Lw%{= rY}%50>%n%f %t%{= bW}%+Lw%< %{=kG}%-=' hardstatus string '%{= kG}[ %{G}%H %{g}][%= %{= kw}%?%-Lw%?%{r}(%{W}%n*%f%t%?(%u)%?%{r})%{w}%?%+Lw%?%?%= %{g}][%{B} %m/%d %{W}%c %{g}]' screen -ln -t "host1" bash split focus top screen -ln -t notes 9 vi /home/user1/notes/notes.txt focus bottom resize 6 focus top bind s

I’ve gotten some help from others around the internet and the Gentoo community wiki was very helpful.

How To Add Programs To Your Startup In KDE

admin — Thu, 18 Sep 2008 00:22:19 +0000

I discovered the best way for me to mount my ssh shares via sshfs automatically when I log in. I add shares and folders from time to time, and I also wanted this technology to automatically be backed up for me, so I wanted the solution to lie inside my home folder. I did some research and learned that KDE has an Autostart folder. For KDE 3.x this is currently at ~/.kde/Autostart, and for KDE4 it is ~/.kde4 (which will eventually drop the 4). I’m already hosting my scripts in ~/bin, so I created a script in that folder to execute sshfs and create the mounts. I then created a link by right-dragging the icon in Konqueror from the ~/bin/ folder to ~/.kde/Autostart. This will work for any executable or script. Now my sshfs mounts automatically at login.

Problems with kdesu via SSH after Hardy Heron Upgrade

admin — Tue, 16 Sep 2008 02:48:47 +0000

I started encountering an error when using kdesu via SSH after Hardy Heron was installed. I’ve since upgraded to 8.04.1 as well and still am running into this bug.

X11 connection rejected because of wrong authentication. kate: cannot connect to X server localhost:10.0

I know I’m not the only Kubuntu user, and there is proof I am not the only user encountering this error. I’ve been getting around it by using gksu which has no problems with my authentication. I suppose I could just alias kdesu and kdesudo (i tried it with no luck too!) to gksu, but I’d like to see an update fix this in the upcoming months. The nice fade effect of gksu is a welcome change sometimes.

SSH Denied Even Though The Keys Are Authorized

admin — Fri, 27 Jun 2008 13:23:14 +0000

I recently had to reinstall one of my servers. It was a pain. I didn’t have the partitions correct, so I lost my web install, and I hate how Ubuntu does not let us put /etc on a separate partition because of init. I struggled for a while with being forced to enter a password when using ssh connections to the re-installed. The output of ssh -vvv user@host indicated the keys were found and authorized, so I was stumped. I asked the North Texas Linux Users Group for some assistance and the first reply pointed me in the right direction. It turns out it was caused by incorrect permissions on my ssh files. To resolve, I used

cd ~ chmod go-w .ssh .ssh/authorized_key*

Webmin is my new favorite admin ninja tool

admin — Sat, 17 May 2008 00:57:45 +0000

I have been struggling for some time with finding a way of properly managing my network, from a easy to use, fast interface. I’m pretty much set in stone that a web solution was what I was looking for. I found it in a tool called Webmin. You can download it from http://www.webmin.com. It’s built on PHP and allows the user to completely administer a system from remote. It has user-programmable modules, so it can be used to configure anything. I especially appreciate the Custom Commands, because it allows me to establish custom buttons that edit specific files. I’m able to use it to manage packages, shares, users, mail, files, apache, mysql, samba, and a whole lot more. To me, the best part of it is I can configure everything in a comfortable interface, from an application that suits my environment, my web browser. The list of available modules is massive! Practically one for every purpose.

Set the Nice Level of an Existing Process

admin — Tue, 29 May 2007 20:23:15 +0000

Occasionally I forget to use the nicecommand. Linux is kind enough to allow us to change the nice level of a process that’s already running, by using the snice command. It’s very easy to use and much quicker than stopping and restarting the process.

Let’s say I have mpeg2enc encoding a video, and after 10 minutes, I realize I forgot the nice command. It’s going to take another hour or two, but I don’t want to waste the 10 minutes I’ve already spent working on the video. No fear!

The command below will save me:

sudo snice -5 mpeg2enc

You’ll notice that I prefixed the line with the sudo command. snice requires sudo privilege for a nice level of anything below zero.

Stacking Commands on the Shell

admin — Wed, 23 May 2007 18:28:49 +0000

Exploiting the shell’s capabilities can be fun and very helpful. Using the shell, I’ll often want to chain commands together. While you may already be familiar with using the semicolon to call commands in the order they were typed on the command line, the shell provides two “constructs” that permit some related, yet very specific behaviors. These constructs are more powerful than simply running commands in a sequence. They allow us to perform a command based on the success or failure of the prior command, and they’re both very easy to use.

The first construct is the double ampersand, &&. When combined with commands on both sides of the double ampersand, the second command will only be executed if the first command was successful. For example, I’ll often execute something like this:

nice unrar e mymoviebackup.rar && rm mymoviebackup.rar

This will delete the original archive, but only if the extraction was successful. On the converse, I may want a command to execute, but only if the first previous command failed. Using the double pipe to separate two commands allows me to do just that.For example,

cp mysysbackup.tar /media/usbdisk1/mytapebackup.tar || touch ~/Desktop/BackupFailed

The above commands works like this : If the copying of mysysbackup.tar to my external drive fails, create or update a file on my desktop that advises me of the failure.

Making the Shell Play “nice”

admin — Wed, 23 May 2007 00:56:09 +0000

Being a big fan of the shell, I make it work hard for me. Often times the commands I’ll issue through the shell are greedy and eat CPU cycles like candy. Sometimes those commands might take several minutes to complete, and I want my CPU’s priority to be focused on other things (like letting me get back to blogging).To handle those special situations for me, I use the “nice” command. It’s really easy. You simply precede any command with the word “nice” and it works it’s magic.

For example, when I’m backing up my email and favorites, I can use the command like this:

nice tar -cf mybackup.tar outlookdata.dat myfavorites.dat

You can tailor nice’s effectiveness to suit your needs, using the -n argument. For example, maybe I want my backup to be priority so that I can get back to what I’d rather be doing. In that case, I’d use:

nice -n=-20 tar -cf mybackup.tar outlookdata.dat myfavorites.dat

Possible values range from -20 (least “favorable”) to 19 (most “favorable”).

bash Wednesday – alias

admin — Thu, 10 May 2007 03:51:22 +0000

One of the best tips I can give on using the command line to your advantage is to grab a hold of the “alias” command. You’re going to be typing a lot of commands, and with Ubuntu, through the bash shell’s glorious “alias” command, they’ll be fewer and shorter.

The alias command allows a shell user to provide their own set of alternate commands for commonly keyed instructions.

The default install of bash includes a few basic aliases, some different modifications of a regular listing of files. Try “ll” for example. While it’s not a command included in Ubuntu and no binary exists for it, the command still provides a more verbose listing of the files. That’s because bash has already defined that alias for you (unless you’ve removed it).

I use the command to make it easy to start and stop my mail server.

alias fymail='vmware-cmd /home/vmware_machines/fymail/fymail.vmx'

Afterwards,

I can use

fymail start

fymail suspend

It may take a little practice and some experimenting, but they save me a lot of time and keystrokes.

You’ll want them to load in your startup of course, so I suggest using

gksu gedit ~/.bashrc

to save your alias commands for future sessions.

The Command Line – Your Computing Co-Pilot

admin — Mon, 07 May 2007 05:09:05 +0000

If you’ve only used Windows, it’s possible you may have neglected one of it’s best hidden gems, the Windows Command Line. While it was very powerful and had many features, it wasn’t quite what Linux and Unix users had been reaping the benefits of for years. It extended upon the original DOS command set, which was always limited to begin with.

Now that you’ve become interested in a Linux distribution, learn early on to integrate your work liberally with the use of the shell’s command line, and you’ll quickly discover you will be saving yourself a lot of time *and* frustration.

The shell’s very powerful, and I obviously can’t cover everything here in this one post, expect to see more helpful guides as far as simple as keystrokes, an array of helpful commands, aliases, links, on to more advanced topics like scripting.