Shell Script to take 2 inputs and process the result

shadownet · 05-24-2013, 01:15 AM

Hi, I am a bit newbie to shell scripting. I want to write a script which takes two inputs 1. Name of the file, 2. No of lines to grep. After taking this two inputs the script should grep no of lines (input 2) from the file (input 1) and put the results into a new file. The new filename can be <filename>.<current date>. So for example if i run the script:

# ./grepscript 100linesoflog.txt 10

This should create a new file called 100lineoflog.txt.20130524 which contains last 10 lines from 100linesoflog.txt

Also if 100lineoflog.txt.20130524 already existed then the new file should be created as 100lineoflog.txt.20130524-1 and if 100lineoflog.txt.20130524-1 exists then script should create 100lineoflog.txt.20130524-2 and so on.

Can someone plz help me write this script. Also since i want to learn please provide explanation on the contents of the script if possible.

Many thanks in advance

chrism01 · 05-24-2013, 01:22 AM

Start with these and see how you go
http://rute.2038bug.com/index.html.gz
http://tldp.org/LDP/Bash-Beginners-G...tml/index.html
http://www.tldp.org/LDP/abs/html/

You would start the script with

Code:

#!/bin/bash

# optionally use next line to debug
set -xv

Note that a comment line starts with '#', UNLESS its the first (physical) line and starts '#!', which the kernel takes a as request to sue the named prog (/bin/bash) to execute the following content.

If you get stuck, post your code using code tags https://www.linuxquestions.org/quest...do=bbcode#code

David the H. · 05-24-2013, 12:53 PM

The description sounds suspiciously like homework to me.

As per the LQ rules we won't give you any direct solutions, but we can help guide you around problems. Please post the work you've done already and explain what you're hung up on.

TB0ne · 05-24-2013, 12:58 PM

Quote:

Originally Posted by shadownet

Hi, I am a bit newbie to shell scripting. I want to write a script which takes two inputs 1. Name of the file, 2. No of lines to grep. After taking this two inputs the script should grep no of lines (input 2) from the file (input 1) and put the results into a new file. The new filename can be <filename>.<current date>. So for example if i run the script:

# ./grepscript 100linesoflog.txt 10

This should create a new file called 100lineoflog.txt.20130524 which contains last 10 lines from 100linesoflog.txt

Also if 100lineoflog.txt.20130524 already existed then the new file should be created as 100lineoflog.txt.20130524-1 and if 100lineoflog.txt.20130524-1 exists then script should create 100lineoflog.txt.20130524-2 and so on.

Can someone plz help me write this script. Also since i want to learn please provide explanation on the contents of the script if possible.

Please spell out your words. And as was said, we will be glad to help you, but we will not write it FOR YOU. Also, saying that you want to learn...so we should explain every step to you...is pretty transparent. That probably means your teacher wants you to explain/show your work.

If you really want to learn, then post what you've written/tried, and where you're stuck, and you'll gladly get help.