colors in bash scripts

I have been trying to understand the color codes for bash for a pretty long time, but somehow never got time to understand this clearly. So this time around when I was writing a script to analyze some logs. I thought I will give it a go and finally understood some part of this.

So, first we will start with this script. This is taken from here.

bash prompts — some good links

Here are some pretty good links on the subject. Since there are already so many blog posts, does not make sense to add one more 🙂

http://tldp.org/HOWTO/Bash-Prompt-HOWTO/c816.html

http://www.gilesorr.com/bashprompt/prompts/

https://bbs.archlinux.org/viewtopic.php?id=84386

Bash themes – http://onlamp.com/onlamp/2006/02/02/bash_themes.html

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• Difference between Bash shell and Bash terminal? (stackoverflow.com)
• The Hollywood Reporter Rounds Up Jessica Chastian and Owen Wilson For a Pre-Oscars Bash (popsugar.com)

15 Linux Bash History Expansion Examples You Should Know

Here is a nice link on BASH History Expansion. There are lot of examples in this page and some of them might be quite useful. But here are my list of favourites:

!!

This is probably the most used one by me. This will repeat the last command. And this works even in conjunction with other commands like

xmlwf – Is your xml document well formed?

There is a small nifty utility called xmlwf that can check your xml documents to see if they are well formed.

sudo yum install expat

Once installed, simply use :

xmlwf

Need more details, just check the man page 🙂

Related articles

• Assigning ID to Objects transmitted in XML document (stackoverflow.com)
• removing characters from php output in xml (stackoverflow.com)
• C# XML parsing using XElement and child contents (stackoverflow.com)

Using file partially for filenames

There are some commands that take file name and there are some case where you need to give file name. But there are some cases where you want to modify the file before passing it to the command. What do you do in these case’s?

I had a file containing huge amount of data and for some testing I wanted to pass only the first few lines of the file and not the complete file.  And since the file only accepted filename and would not take any input from the STDIN so only option was to create a file with the required data in a temporary file. So, I sat back to figure out some way to do it and finally found I can use this:

Benchmarking the system/CPU performance

Have you ever wanted to have a quick check on your CPU performance. I know that lot of people will say that this is not the right way to do this, but here is something that you can use to check the CPU speed.

#!/bin/bash -
#===============================================================================
#
#          FILE:  benchmark.sh
#
#         USAGE:  ./benchmark.sh
#
#   DESCRIPTION:  Benchmark the CPU
#
#       OPTIONS:  ---
#  REQUIREMENTS:  ---
#          BUGS:  ---
#         NOTES:  ---
#        AUTHOR: Amit Agarwal (aka), amit.agarwal@roamware.com
#       COMPANY: Roamware India Pvt Ltd
#       CREATED: 09/21/2011 11:46:03 AM IST
# Last modified: Wed Sep 21, 2011  12:22PM
#      REVISION:  ---
#===============================================================================

add ()
{
    COUNTER=0
    exec 2>&1
    time=$(exec 2>&1;(time while [[  $COUNTER -lt 100000 ]]; do ((COUNTER++)) \
        ; done))
    echo "Time for 100000 additions is "$time
}	# ----------  end of function add  ----------
mul ()
{
    COUNTER=0
    test=2
    exec 2>&1
    time=$(exec 2>&1;(time while [[  $COUNTER -lt 100000 ]]; do ((COUNTER++)) \
        ; ((test=test*2));done))
    echo "Time for 100000 mul is "$time
}	# ----------  end of function add  ----------
div ()
{
    COUNTER=0
    test=1000000000000
    exec 2>&1
    time=$(exec 2>&1;(time while [[  $COUNTER -lt 100000 ]]; do ((COUNTER++)) \
        ; (( test=test/2)); done)|tr -d '\n')
    echo "Time for 100000 divisions is "${time}
}	# ----------  end of function add  ----------

time add
time mul
time div

And here is the output :

conky script used to monitor server status remotely.

[][1]

I was looking for something to monitor few details on the server. I thought about quite a lot of applications, some open source and some scripts developed in house. But my requirements were quite petty and the scripts and applications were quite heavy. So, I thought why not conky :).

So, with some quick work on conky script, I was able to get what I wanted and here it is for all of you.