[SOLVED] How to write a replacement for shell command line interpreter

whirlpool · 09-02-2010, 07:27 AM

Hey,
If say, I want to read the input given by user at the command prompt and write a code to execute the cmd given then which commands do i use to implement this ( Im writing the code in C )?
Please give me a hint as to how do i start ?

Thanks
Ambika

estabroo · 09-02-2010, 07:31 AM

I'd use the readline library for taking the input, full line editing capabilities. As far as executing the command you'd probably want to do a fork and then exec (from the child process of the fork)

giammy · 09-02-2010, 09:23 AM

Quote:

Originally Posted by whirlpool

Hey,
If say, I want to read the input given by user at the command prompt and write a code to execute the cmd given then which commands do i use to implement this ( Im writing the code in C )?
Please give me a hint as to how do i start ?

Thanks
Ambika

Hi,

I would look for this in Google ... something such as the following could come out :-)
http://rik0.altervista.org/snippets/csimpleshell.html

bye
giammy

chrism01 · 09-03-2010, 12:51 AM

In this particular case, google would be a good idea, not because I don't want to help you (I do), but because that is a very popular homework / project question in college, as a result of which, there are loads of comments/tips on this very qn on the internet by now.

Aquarius_Girl · 09-03-2010, 01:29 AM

See if this thread helps you :
http://www.linuxquestions.org/questi...-shell-775690/

and the Programming questions should be placed here:http://www.linuxquestions.org/questions/programming-9/

Tinkster · 09-05-2010, 02:27 AM

Moved: This thread is more suitable in <PROGRAMMING> and has been moved accordingly to help your thread/question get the exposure it deserves.

Sergei Steshenko · 09-05-2010, 02:30 AM

Quote:

Originally Posted by estabroo

I'd use the readline library for taking the input, full line editing capabilities. As far as executing the command you'd probably want to do a fork and then exec (from the child process of the fork)

'system' is simpler than 'fork', 'exec' to use and probably is sufficient in this case.

estabroo · 09-05-2010, 08:12 AM

Quote:

Originally Posted by Sergei Steshenko

'system' is simpler than 'fork', 'exec' to use and probably is sufficient in this case.

It is simpler but why involve yet another shell when you are trying to replace one.

With fork/exec you have more control over how the parent deals with the child process, for example how it's stdin/stdout/stderr are attached, or what other file descriptors are left open for the child to access, or being able to send the child process signals.

I guess it just depends on what the OP wants to get out of this coding exercise.

whirlpool · 09-06-2010, 07:20 AM

Thanks to all for the help offered.