Ubuntu For Free » bash

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.

Quick alias to update your packages via aptitude

admin — Fri, 27 Mar 2009 03:06:21 +0000

I use the command line more than anything, and I try to stay up to date regularly, so I added an alias for the command I use for updates.

alias apt-up='sudo aptitude -y update && sudo aptitude -y full-upgrade '

My Useful In Folder Script

admin — Sun, 06 Apr 2008 03:55:25 +0000

Having been a long time user of 4DOS in my pre-win95 days, I had developed some batch files and/or aliases that I were quite handy in that environment. Switching to another operating system that’s more flexible with the command line, I’ve re-implemented some of those batch files and aliases. Here’s one of my favorites, and while it’s pretty simple, I use it all the time. It switches to a folder using the pushd command, executes your chosen command, and then uses popd to switch back to the original folder. It has no error checking of it’s own and it has no instructions. I did it in this fashion to keep it as light and quick as possible.

#!/bin/bash ## In Folder script by Joshua Kersey ## http://www.forwardyouth.com/ubuntu pushd "$1" "$2" popd

Let me know if you’ve got any suggestions for improvement.

Kubuntu Software Review – Konversation

admin — Wed, 12 Dec 2007 04:53:25 +0000

My first install of Ubuntu was Dapper Drake, and it was the original flavor, with the Gnome desktop. It included XChat, which seemed an easy transition from mIRC. Since I’d previously managed IRC connections using telnet, it wasn’t daunting. However, after switching to Kubuntu, I found myself presented with Konversation. It might have been my previous experience with mIRC, but I almost felt right at home.

In comparison to XChat, I feel it’s better at managing connections to multiple servers. The servers are spawned as separate tabs, where XChat *tried* to do it in a tree-like view, it failed and inserted the additional servers as child-nodes of the first-connected server.

Using bash scripts, we can make Konversation take action. It requires the DCOP protocol, a newer method permitting KDE applications to communicate between each other. Known as an Inter-Process Communication, DCOP providesthe ability to send DCOP messages to/from any other KDE app, allowing Konversation to integrate nicely with Amarok (i.e. to announce the “now-playing” track) and other KDE software (i.e. getting data from “weather” or sending/retrieving information with “kate”).

One of my favorite features, is the On-Screen Display, abbreviated as OSD. This feature provides a miniaturized display of text in a separate screen area. For example, we can see entire messages directed to us, even when Konversation is minimized, through the OSD, when Konversation is able to determine our nick.

You can also configure notifications, or specific actions when selected events occur, including pop up messages (optionally passive), sounds, shell commands, log insertions, etc.

I have plans for a couple of scripts for the application, so I think I’m going to try my hand coding something different.

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.