Shell Script that accepts a positive integer and returns comma separated list of integers in descending order

Description: 

Write a  shell script that accepts exactly 1 argument which must be a positive integer. 

The script will print a comma-separated list of integers, all on the same line in descending order

Script: decreaseNum.sh

 

#!/bin/bash

#-----------------------------------------------

#user input

num=$1

temp=''

         

        #continue while input is greater than 0
 while [ $num -gt 0 ]
 do

                #append the numbers in decreasing order with comma-separated
  temp+="$num, "
  num=$(( $num - 1 ))
    done
 temp=$(echo $temp | sed 's/,$//')

 echo $temp

Output:

Shell Script: Get the Average Grade of a Student

Write a shell script, which gives back the average grade of a student The student name we should give as a parameter! If you give a name that is not in the data file, please write out an error message and write out the list of the names (Just the names without the grades!!!) as a help!

input file: class.txt

Name/Math Informatics Literature English
Mohammed 3 4 5 4
Alan 2 1 3 2
Li 3 5 1 3
Jane 4 2 3 1

SCRIPT:

#!/bin/bash

# Variable Declaration
input_file="./class.txt"
name=$1
average=0
err_msg="\n\tPlease pass a student name to the script. \n\te.g.: ./average.sh Tom \n" 
name_list=`cat class.txt | awk '(NR != 1) {print $1}' | tr "\n" ","  | sed -e 's/,$//' -e 's/,/, /g' `
#---------------------------------------------------------------------------------------------
if [ -z "$name" ]
then
echo -e "$err_msg"
else
record=$(grep -w "$name" $input_file)
if [ -n "$record" ]
then
#sum=$(echo $a | awk '{sum=0; for (i=2; i<=NF; i++) { sum +=i} print sum }')
average=$(echo $record | awk '{sum=0; for (i=2; i<=NF; i++) { sum +=$i} print sum/(NF - 1) }')
echo -e "\t $name $average \n"
else
echo -e "No $name is in the list. There are: $name_list"
fi
fi

let's check the output:

Shell Script: Write 000 to 999 (1000 lines in a file) using Brace Expansion

We need to write from 000 to 999 in a file. As these are consecutive numbers we will be using "Brace Expansion"

Let's Create a file by using the touch command.

Script:

 #create an empty file
touch output.txt 

#using brace expansion with foor loop

 for i in {000..999} #this is brace expansion

do

    #append data to output.txt 

    echo $i >> output.txt

done

Output: 

To see the output use bellow command

        cat output.txt | more 

Shell Script: find the 5 most frequent words in an article

Shell Script to find the 5 most frequent words in an article.

Article:

The company's rapid growth since incorporation has triggered a chain of products, acquisitions, and partnerships beyond Google's core search engine (Google Search). It offers services designed for work and productivity (Google Docs, Google Sheets, and Google Slides), email (Gmail), scheduling and time management (Google Calendar), cloud storage (Google Drive), instant messaging and video chat (Duo, Hangouts, Chat, and Meet), language translation (Google Translate), mapping and navigation (Google Maps, Waze, Google Earth, and Street View), podcast hosting (Google Podcasts), video sharing (YouTube), blog publishing (Blogger), note-taking (Google Keep and Google Jamboard), and photo organizing and editing (Google Photos). The company leads the development of the Android mobile operating system, the Google Chrome web browser, and Chrome OS, a lightweight operating system based on the Chrome browser. Google has moved increasingly into hardware; from 2010 to 2015, it partnered with major electronics manufacturers in the production of its Nexus devices, and it released multiple hardware products in October 2016, including the Google Pixel smartphone, Google Home smart speaker, Google Wifi mesh wireless router, and Google Daydream virtual reality headset. Google has also experimented with becoming an Internet carrier (Google Fiber, Google Fi, and Google Station)

let's store the text in a file named 'google.txt'

Command:

cat google.txt | tr '[ :upper: ]' '[ :lower: ]' | grep -oE '\w+' | grep -vE "and|has|of|the|has|with|an" | sort | uniq -c | sort -nr | head -n 5

Output:

cat - to display the content of the file

tr '[ :upper: ]' '[ :lower: ]'  - convert all uppercase to lowercase

grep - to find particular words

sort - sort the list of words here

uniq -c  - it provides the count of unique words 

head - it provides the top few lines from the list or file