Scripting on Amit Agarwal Linux Blog

Color-Coded URL Status Checker in Bash: Enhanced Script for Fast Web Health Monitoring

Fri, 17 Oct 2025 00:00:00 +0530

Upgrade your Bash scripting game with a color-coded URL status checker that leverages curl, timeout handling, and clean output for fast web monitoring.

Hackernews In Your Inbox

Sun, 25 Aug 2024 00:00:00 +0530

If you do not want to subscribe to any newsletter but still want to get some news delivered to you inbox then this post is for you.

First you need to get a script that can pull the hacker-news articles for you and you can find my script here. You can modify this script, specially the line: for id in trending_list[:50]: to change the number of posts that you would like to see in the mail.

Warn when battery is low

Sun, 30 Aug 2020 00:05:57 +0530

I am very lazy to look at battery status and want to be warned when the battery is low. This means that even if I am away from the laptop, I can be warned that laptop is about to poweroff due to battery low. So, what kind of alerts I can have, many -

zenity message box
email
sms with twillio
Telegram message and possibility is endless.


LOW=35 ## This si the lowest percentage at which I want the alerts.
## Parse the acpi statue and decide if alert needs to be sent
per=$(/usr/bin/acpi -b | awk '{print $4}'|sed 's/%.*//') 

# source ~/bin/cron-scripts/sendsms.sh
if [[ $(/usr/bin/acpi |grep -c "Full\|Charging") > 0 ]]
then
    #This is when the AC is connected.
    exit 0
fi


if [[ ! -z $per && $per < $LOW ]]
then
    # sendsms "Battery is at $per%"
    export sub="Battery is at $per%"
    echo "Battery is running out : $per"|/usr/sbin/sendmail -t
    display_msg.sh "ACPI Warn" "Battery is at $per%"
    echo "ACPI Warn" "Battery is at $per%" | /home/amitag/bin/twilio-sms +919535210501
    zenity --warning --text="Battery is at $per%"
fi

Put this script somewhere and schedule in cron for every minute and enjoy.

Some good find alias.

Sun, 23 Aug 2020 11:05:57 +0530

Here are some interesting alias’s that you may want to add to your bashrc file or where-ever else you add your aliase’s. Very useful if you use find commonly.

There are four aliases defined here and have a comment explaining what it does. but these are so simple and useful that you probably dont even need the comments.


# ff:  to find a file under the current directory
ff () { find . -name "$@" ; }
# ffs: to find a file whose name starts with a given string
ffs () { find . -name "$@"'*' ; }
# ffe: to find a file whose name ends with a given string
ffe () { find . -name '*'"$@" ; }
# very very useful function: for finding files with ignore case, just type "f <part of filename>"
# This in combination with alias for 'g' is deadly.
#
f () { find . -iname '*'"$@"'*' ; }

Hope this is useful for you.

Books menu with bash

Sun, 16 Aug 2020 11:05:57 +0530

If you have a folder full of ebooks in various formats and not necessarily one sigle format and you want to have a quick menu to browse though your collection without requiring to open a File Manager then you are going to love this script.

The scripts works by allowing you to browse to the requied folder of your choice and once you select the file, then using xdg-open to open the file with your default viewer.

Pygmentize Styles

Sun, 26 Jul 2020 18:38:57 +0530

I have recently started using pygmentize for looking at my code in terminal. A very good and native way to do this is to use pygmentize. If you do not know about pygmentize then

Highlight the input file and write the result to . If no input file is given, use stdin, if -o is not given, use stdout.

So, you can simply pass the script or source code through pygmentize and get a lovely color output with code highlighting in the terminal and this can be very useful.

scripting – performance improvement with file open

Mon, 20 Apr 2020 01:01:37 +0000

Sometimes just one line of code can make all the difference. I will show you with example.

Here is script with 2 functions. Both are writing some lines of text to a file. First function, “a” I have used the redirection to write to file. Function “b”, I have opened a file descriptor with “>” before going into the loop and use that reference for writing to the file. (This concept remains same for any scripting or programming language).

i3 – show mapped hotkeys

Mon, 02 Dec 2019 01:05:19 +0000

Here is a simple script that can show you the hotkeys bound in ~/.config/i3/config :

#!/bin/bash - 
#===============================================================================
#
#          FILE: i3-showkeys.sh
# 
#         USAGE: ./i3-showkeys.sh 
# 
#   DESCRIPTION: 
# 
#       OPTIONS: ---
#  REQUIREMENTS: ---
#          BUGS: ---
#         NOTES: ---
#        AUTHOR: Amit Agarwal (aka)
#  ORGANIZATION: Individual
#       CREATED: 11/26/2019 14:22
# Last modified: Tue Nov 26, 2019  02:43PM
#      REVISION:  ---
#===============================================================================

set -o nounset                              # Treat unset variables as an error


> /tmp/keys
cd ~/.config/i3
grep '^bindsym $mod' config|grep -v '^#'|grep -v 'move container to'|grep -v 'workspace $ws'|sed 's/bindsym //'|grep -v '='|while read key line
do
    printf "%20s\t?\t%s\n" "$key" "$line"  >> /tmp/keys
done

xterm -e "cat /tmp/keys; read -p 'press any key to continue'"
rm -f /tmp/keys

And once this is done, you can bind the script in i3 config like this:

scan your network with bash IP scan script

Thu, 10 Oct 2019 07:05:41 +0000

Here is the youtbe video that will walk you through bash script.

cool sed/grep magic to convert output to csv format

Mon, 11 Mar 2019 01:12:34 +0000

I generallly keep doing this a lot, so thought will share with you. Lets assume we are capturing free ouput every min/hour/or whatever. The output looks like this:

Time: Mon Jan 21 23:59:10 AEDT 2019
——————-

total used free shared buff/cache available
Mem: 32014 8656 1735 1697 21621 21308
Swap: 51195 75 51120

then we can use some grep and sed to convert this to something like this:

Mon Jan 21 23:59:10 AEDT 2019,32014,8656,1735,1697,21621,21308

Get to your ebooks quickly

Mon, 12 Nov 2018 01:05:03 +0000

So this is going to be a little longer post than usual.

To begin with, here is screenshot of how it would look like finally:

Generate random string for various use case

Mon, 08 Aug 2016 01:16:14 +0000

Some times I need random string, for example to use as email seperator or to use in some API. One way is to use tools like /dev/[u]random or od and other such. But they seem cubersome after I figured this out.

openssl rand <length>
openssl rand 10

This alone without some parameters is not interesting thoug. You can use ‘-base64’ or ‘-hex’ to select the encoding.

So if you execute the above you will get something like this

image ordering by Original Date Time using bash script

Tue, 05 Jan 2016 00:55:10 +0000

Here is the script:

#!/bin/bash -
#===============================================================================
#
#          FILE: imgOrg.sh
#
#         USAGE: ./imgOrg.sh
#
#   DESCRIPTION:
#
#       OPTIONS: ---
#  REQUIREMENTS: ---
#          BUGS: ---
#         NOTES: ---
#        AUTHOR: Amit Agarwal (aka)
#      REVISION:  ---
#===============================================================================

for i in *
do
    if [[ $(file $i) == *image* ]] 
    then
        echo "Image file is :: $i"
        dir=$( exiftool -s -DateTimeOriginal $i | awk -F':' '{print $2"/"$3}')
        mkdir -p $dir
        cp $i $dir/
    else
        echo "Excluding $i"
    fi
done

Get count of lines in scripts (shell)

Thu, 15 Oct 2015 00:41:52 +0000

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:

Filename handling with space and newline character.

Tue, 25 May 2010 11:34:01 +0000

<a target="_blank" href="http://www.andreaplanet.com/andreamosaic/download/">
<a href="http://calypso.tux.org/pipermail/novalug/2009-February/017524.html">[Novalug] Filename handling: correctness vs. convenience has a nice post from Michael Henry on Filename handling.

The power of find command in Linux – advanced.

Mon, 24 May 2010 16:25:40 +0000

Generally whoever uses Linux, would know about the find command. Find the man page <a href="http://amit.themafia.info/phpMan.php?parameter=find&mode=man" target="_blank">here.

There are also lots of blogs, tutorials and other articles on find command on the web, so why write another one. Because it’s worth every word spent on it 🙂
find is a very powerful command, let’s see how (options for find command from man page and usage):

–depth — Process each directory’s contents before the directory itself.
–maxdepth — Descend at most levels (a non-negative integer) levels of directories below the command line arguments.
–xdev — Don’t descend directories on other filesystems.
–executable — Matches files which are executable and directories which are searchable (in a file name resolution sense).
This takes into account access control lists and other permissions artefacts which the -perm test ignores.
–iname — Like -name, but the match is case insensitive.
–nogroup — No group corresponds to file’s numeric group ID.
–nouser — No user corresponds to file’s numeric user ID.
–fls file — True; like -ls but write to file like -fprint.
–ok command — Like -exec but ask the user first (on the standard input);
–print0 — True; print the full file name on the standard output, followed by a null character
(instead of the newline character that -print uses).
–printf format — True; print format on the standard output, interpreting ’’ escapes and ’%’ directives.

parse and paste text

Mon, 01 Jan 0001 00:00:00 +0000

Lot of times, I copy the text but before pasting want to remove a word or make some other changes or add “wget” to the URL, quite common. So, I came up with this alias

replace='echo $(xclip -i)|sed 's/text//'|xclip -o'

and this depends on xlip, which you can install with

dnf install xclip