bash completion

I was working on some functions in bash to make my life easier and realized that if I added custom completion to my functions, it will be really good. So I headed over to google and searched for what I wanted. I did get a lot of information on bash completion but not a single concrete example that could help me do what I wanted. So, with the help of man pages and some results from the Google pages, I was finally able to accomplish what I wanted. So here it is:

faster bash operations on files with File Descriptors.

I was writing a bash script that would do some operations and read and write to file. Seems that that was pretty simple with

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      while read line<br /> <br /> do<br /> <br /> done<file
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and then use redirection operations like “>” and “»” to write to file. Done with the script pretty fast. So far so good, when I went for real life tests, no one was interested in using it, why? Simple, it was simply taking too long. The file was reading about 10K lines and writing about 50 lines and was taking about more than 10 minutes.

Unix shell script for removing duplicate files

The following shell script finds duplicate (2 or more identical) files and outputs a new shell script containing commented-out rm statements for deleting them (copy-paste from here):

::: updated on 02 May 20121, seems like wordpress did not like it so well so reformatting the code :::::::

#!/bin/bash -
#===============================================================================
#
#          FILE:  a.sh
#
#         USAGE:  ./a.sh
#
#   DESCRIPTION:
#
#       OPTIONS:  ---
#  REQUIREMENTS:  ---
#          BUGS:  ---
#         NOTES:  ---
#        AUTHOR: Amit Agarwal (aka), amit.agarwal@roamware.com
#       COMPANY: blog.amit-agarwal.co.in
#       CREATED: 02/05/12 06:52:08 IST
# Last modified: Wed May 02, 2012  07:03AM
#      REVISION:  ---
#===============================================================================

OUTF=rem-duplicates.sh;
echo "#!/bin/sh" >$OUTF;
find "$@" -type f -exec md5sum {} \; 2>/dev/null | sort --key=1,32 | uniq -w 32 -d |cut -b 1-32 --complement |sed 's/^/rm -f/' >>$OUTF

Pretty good one line, I must say 🙂

Terminating a SSH session after starting background process.

This is too good. If you are planning to start a background process in the bash script in the background and continue in the script, you cannot do it until…….

You would need to close the stdout/stdin and stderr before you can terminate any ssh session automatically. Here’s some more light on this topic.

http://lists.debian.org/debian-user/2005/09/msg00254.html

On Thu, Sep 01, 2005 at 05:33:28PM -0400, Roberto C. Sanchez wrote: > I occasionally log into a machine remotely and start a process in the > background: > > command & > > However, when I log out of the machine, the ssh process on my local > machine blocks. I guess that it is becuase the remote still has jobs > running. Is there a way to get it start the process in the background > and then detach from the shell? I have already tried this:

cd across parallel directories

Here is a simple and fast way to cd across parallel directory.

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      cd ${PWD/test/actual}
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/bash debugger

9.2. A bash Debugger

In this section we’ll develop a very basic debugger for bash.[10] Most debuggers have numerous sophisticated features that help a programmer in dissecting a program, but just about all of them include the ability to step through a running program, stop it at selected places, and examine the values of variables. These simple features are what we will concentrate on providing in our debugger. Specifically, we’ll provide the ability to:

some bash exercise for you

Here is some teaser for you, can you figure out how this works:

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      echo ls<br /> <br /> !!:1-$
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