Get count of lines in scripts (shell)

If you have tried to get the count of lines in file, the you would know about “nl” or “wc -l”. But as you are aware these give you number of lines with other details as well and you need to post process the number to make sure that you have only number and nothing else. In such cases, it is useful to use the count feature of grep and here is a shorthand to get the count of lines in any shell script:

bash – refer the first parameter from last command quickly

To refer to first parameter from the last command quickly, you can use

!^

Note: This can also be referred as “!!:1“

bash refer parameters from the current command

In bash you can use

!#

to refer to any parameter from the current command, example:

mv ak amit.!#:1.txt
ls amit.ak.txt

bash debug – log all executed commands

Whenever I am writing a script in perl or bash, I always wish that there
was some way to have all the commands logged or output to screen. I know
there is “set -x” option to have debugging enabled, but sometimes that
seems to be too much information and I dont really need all that. So, here
is something I found recently for bash to log all the executed commands.

bash – using the vi mode more effectively.

You can first set the bash mode to vi. This will enable some vim like features to bash. So, add this to .bashrc :

set -o vi

Once, you have done that then its time to get more out of the vi mode. First, check some things and set some interesting stuff.

Shortcut to run current command with sudo in bash

For me, I mostly forget to add “sudo” to the command until the time I am actually supposed to run it. Also sometimes, on some systems, bash completion does not work as expected with “sudo”. With these in mind, I wanted something such that when I have completed the command, I could insert sudo in the begining of the command without much ado. So, finally this is what I came up with in my “~/.inputrc” file. Note: If you don’t have this file, then simply create this file.

Array of all possible colors in bash script

Sometime back, we had looked at using colors in bash script and here is a way to create a array of all the colors.

#!/bin/bash - 
#===============================================================================
#
#          FILE:  colorarray.sh
# 
#         USAGE:  ./colorarray.sh 
# 
#   DESCRIPTION:  
# 
#       OPTIONS:  ---
#  REQUIREMENTS:  ---
#          BUGS:  ---
#         NOTES:  ---
#        AUTHOR: Amit Agarwal (aka), amit.agarwal@roamware.com
#       COMPANY: Roamware India Pvt Ltd
#       CREATED: 16/04/12 17:24:09 IST
# Last modified: Mon Apr 16, 2012  05:39PM
#      REVISION:  ---
#===============================================================================
count=0
for i in 40m 41m 42m 43m 44m 45m 46m 47m
do
    for l in 0 1
    do
        echo -n "l=$l "
        for k in 0 1
        do
            # echo -n "k=$k "
            for j in {30..37}
            do
                carr[$count]="\033[$k;$j;$l;$i"
                echo -ne "${carr[$count]}$count \033[00m"
                ((count++))
            done
        done
        echo
    done
    echo
done

You can add this script to any script of your choice and you have all the 256 colors available to you in the script without additional coding. Happy coding.