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

Describe Priority Scheduling algorithm of operating system?, Priority Sched...

Priority Scheduling • The fundamental idea is straightforward: each process is assigned a priority, and priority is permitted to run. Equal-Priority processes are scheduled in FCF

Copmurer, Classify computer systems according to capacity. How they are dif...

Classify computer systems according to capacity. How they are different from computers according to the classification of technology. Provide comparative study also.

Collaboration, Collaboration: Collaboration is defined as an act or pr...

Collaboration: Collaboration is defined as an act or process of working together on a project or some intellectual activity. But what is the importance of collaboration? The w

Meaning of primary data, Problem 1 Research designs have a critical and...

Problem 1 Research designs have a critical and directive role to play in the research process. Explain the meaning of research design. Describe the various types of research de

Assembly language, write and run the following programs using 8086 assembly...

write and run the following programs using 8086 assembly language that interchange the upper and lower four bits of AL register.

Data output, DATA OUTPUT : Whatever, data or information that you feed int...

DATA OUTPUT : Whatever, data or information that you feed into a computer will be the data output from a computer system and will be a data file sent from the computer to a periph

Read world population data file. store the values in multipl, Read World Po...

Read World Population Data File. Store the values in multiple vectors. Sort them by most populated region and output the results ext file is here : please">http://www.csupomona.

Python - Dictionary, A dictionary is variable and is one more container typ...

A dictionary is variable and is one more container type that can store any number of Python objects, counting other container types. Dictionaries consist of pairs (identified items

Artificial intelligence-environments, Artificial Intelligence-Environments ...

Artificial Intelligence-Environments   We have seen that intelligent agents should take into description sure information when   choosing  a rational act,  including inform

With an example, Question 1 With an example, illustrate the concept of ext...

Question 1 With an example, illustrate the concept of extern variable Question 2 What is the difference between pointer variable and simple variable? Question 3 Give the

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