Splitting strings with IFS

2010-02-04 2 min read Bash Linux

Today I want to discuss splitting strings into tokens or “words”. I previously discussed how to do this with the <a href="http://bashcurescancer.com/reading-a-file-line-by-line.html">IFS variable and promised a more in depth discussion. Today, I will make the case on WHY to use IFS to split strings as opposed to using a subshell combined with <a class="zem_slink freebase/en/awk" title="AWK" rel="homepage" href="http://cm.bell-labs.com/cm/cs/awkbook/index.html">awk or cut.

I wrote this script which reads the /etc/password file line-by-line and prints the <a class="zem_slink freebase/en/user" title="User (computing)" rel="wikipedia" href="http://en.wikipedia.org/wiki/User_%28computing%29">username of any user which has a UID greater than 10 and has the shell of /sbin/nologin. Each test function performs this task 10 times to increase the length of the test:

Color output from ls – based on file type

2010-02-04 1 min read Bash Linux

Threre are certain default variables which control the color of the output from the ls command, so we will talk about them today.

The first one is to get the color output from the ”ls” command. We will look at the various ways to do this:

First is to use this with default colors:

ls –color=auto

Now this will use the default colors which might not go with your liking 🙂 So if you want to change the colors you can use the variable called LS_COLORS.

Bash styling(themeing), the stylist way.

2010-02-04 1 min read Bash

For last couple of days, I have been looking for solutions to make stlying my bash easier. So, first a screenshot of the effort:

I was looking for the simplest solutions to do this. So, I installed two packages to make my life easier : bashstyle and fortune.

sudo yum install fortune\*

For bash-style you can download the source files <a href="http://www.nanolx.org/bashstyle-ng/" target="_blank">here. Download the file, then do the following:

grep -v with multiple patterns.

2010-01-25 1 min read Bash Linux

$ sed '/test/{/error|critical|warning/d}' somefile If you wanted to do all in one command, you could go w/ sed instead

<a href="http://www.commandlinefu.com/commands/view/3882/grep-v-with-multiple-patterns.">View this command to comment, vote or add to favourites
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by David Winterbottom (<a href="http://codeinthehole.com">codeinthehole.com)

URL: <a href="http://feedproxy.google.com/~r/Command-line-fu/~3/LjKzo7FpzDU/grep-v-with-multiple-patterns.">http://feedproxy.google.com/~r/Command-line-fu/~3/LjKzo7FpzDU/grep-v-with-multiple-patterns.<h6 class="zemanta-related-title" style="font-size: 1em;">Related articles by Zemanta <ul class="zemanta-article-ul"> <li class="zemanta-article-ul-li"><a href="http://www.seroundtable.com/archives/020935.html">Google’s ”Show More Results” Plus Box (seroundtable.com) <li class="zemanta-article-ul-li"><a href="http://www.macworld.com/article/143351/2009/10/netprocesses.html?lsrc=rss_main">See which processes are using the Internet (macworld.com) <div class="zemanta-pixie" style="margin-top: 10px; height: 15px;"><a class="zemanta-pixie-a" title="Reblog this post [with Zemanta]" href="http://reblog.zemanta.com/zemified/cc60245b-7397-4d48-83b2-7bfb345ae7a9/"><img class="zemanta-pixie-img" style="border: medium none; float: right;" src="http://blog.amit-agarwal.co.in/wp-content/uploads/2010/08/reblog_e20.png" alt="Reblog this post [with Zemanta]" /><span class="zem-script more-related pretty-attribution">

Seders\’s grab bag – Tutorials

2010-01-24 3 min read Bash Fedora Learning Linux

<a href="http://sed.sourceforge.net/grabbag/tutorials/">http://sed.sourceforge.net/grabbag/tutorials/

<span style="font-size: x-large;"><a href="http://sed.sourceforge.net/grabbag/">seder’s<a href="http://sed.sourceforge.net/grabbag/"> grab bag

<a href="http://sed.sourceforge.net/grabbag/scripts/">scripts
<a href="http://sed.sourceforge.net/grabbag/tutorials/">tutorials
<a href="http://sed.sourceforge.net/grabbag/seders/">seders
<a href="http://sed.sourceforge.net/grabbag/ssed/">ssed
<a href="http://sed.sourceforge.net/grabbag/links/">links
<a href="http://sed.sourceforge.net/grabbag/tutorials/#intros">Intros
<a href="http://sed.sourceforge.net/grabbag/tutorials/#advanced">Advanced
<a href="http://sed.sourceforge.net/grabbag/tutorials/#misc">Miscellaneous

<span style="font-size: large;">Sed Tutorials

If you have written anything about sed – whether an introduction, how sed got you out of a real-life situation, or perhaps an advanced technique you’ve discovered – you may like have your work published here. <a href="mailto:bonzini@gnu.org">Your contribution will be very welcome.

change the terminal title dynamically in X11

2010-01-09 1 min read Bash GNOME Linux

I was actually looking for this for quite sometime. Some years back in my bashrc was the proper setting for setting the terminal title when I did a cd, and I had completely forgotten how to do it. So today I searched quite a few commands the environment variables for doing the same and found it again.

Here it is (Just put this in your bashrc or bash_profile):

export PROMPT_COMMAND=’echo -ne ”\033]0;`pwd`”; echo -ne ”\007”’
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shell — one liner to selectively change case

2010-01-07 2 min read Bash

Today I had a hard time, I had a herculian task of converting the case of file to upper case. Well that’s not difficult :), I know. What made it difficult was the fact that not the whole file had to be converted but only selective lines containing the work important. Okay now that too is not so difficult, I thought. But again the file size was huge, it had some 9 million lines. So, I just thought of trying my skills of shell programming (dont have much of it anyway). So here’s what I did:

<span style="font-size: x-large;"><a href="http://sed.sourceforge.net/grabbag/">seder&#8217;s<a href="http://sed.sourceforge.net/grabbag/"> grab bag

<span style="font-size: large;">Sed Tutorials

<span style="font-size: x-large;"><a href="http://sed.sourceforge.net/grabbag/">seder’s<a href="http://sed.sourceforge.net/grabbag/"> grab bag