Unix Shell, Basic Computer Science

Assignment Help:
Write a shell script, change-lines, which will substitute a string for a replacement string for each occurance of the string in files specified.
The original file will be saved, with the same filename with the .keep extension unless the -n option is present.

You may use a temporary file for this script.

Remember the search string and or the replacement string can have special characters in them, so you must use proper quoting techniques.

The script will use following options:


the option -s "string" for the search strings
the option -r "string" for the replacement string
the -n option to prevent a backup file from being created
the -h option to print a usage statement and exit
The script will exit with an error status and print an error message:
if the -s option is not present.
if the -r option is not present.
if the string is not specified with the -s option
if the string is not specified with the -r option
if there are any other options specified
if there are no input files specified
if the input file cannot be read by the current process
if the input file cannot be written by the current process
if you cannot create the backup file.
Here is the usage statement for the script:
change-lines [-n] -s search string -r replace string files ...
-n do not backup the original file
-s search string the search for this string
-r replace string replace the search string with this string
-h print this message

Related Discussions:- Unix Shell

Cryptography, Consider the one-time pad encryption scheme to encrypt a 1-bi...

Consider the one-time pad encryption scheme to encrypt a 1-bit message m, and assume m is chosen with uniform distribution from message space M={0,1}. Let E1 be the event "message

Internal structure of agents - artificial intelligence, I n t e rnal St...

I n t e rnal Structure of Agents We have looked at agents in terms of their external influences and behaviors: they take input from the environment and perform rational act

Paper system, Paper System : When setting up a computer system you need to...

Paper System : When setting up a computer system you need to ask yourself 'Does the system you plan to operate work manually, i.e., on paper?' It is a popular misconception that t

What are the most common forms of mixing, Question 1 What is the differenc...

Question 1 What is the difference between Variable Bit Rate and Constant Bit Rate? Question 2 Write a note on: Normalization, Reverberation, Noise Reduction, Filters, and

What do you mean by geo stationary orbit, Question 1 . Explain (a) Scatter ...

Question 1 . Explain (a) Scatter loss                                (b) Aperture medium coupling loss Question 2 . What do you mean by Geo stationary orbit? Question

What is nanp? explain, Question 1 What is NANP? Explain Question 2 ...

Question 1 What is NANP? Explain Question 2 What is E&M signaling? Discuss in brief Question 3 What are the common custom calling features? Question 4 Expl

I/O Stream and Arrays, Write a program that: 1. Ask the user for names of t...

Write a program that: 1. Ask the user for names of the two iput files and a name of an output file. The two input files contain integers in any order. Eachimput file contains no mo

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd