topic Re: C: How to pull in info from the system? in Operating System - Linux

C Programming Language: How To Pull In Information From The System?

tony j. podrasky — Sat, 16 Aug 2014 04:57:05 GMT

Hello Everyone;

I want to run the <apm> command, from withing a C program, and get the program to receive the output - so that I can display it in an xsession (window) on my screen.

I've used the <system> call to tell the O/S what to do - but I don't know where to look to find out how to issue a system call and have the program receive the output.

Any ideas are appreciated.

regards,

tonyp

Re: C: How to pull in info from the system?

Dennis Handly — Sat, 16 Aug 2014 08:34:44 GMT

The correct function is popen(3) with the "r" parm. Or you could use pipe(2) with fork(2)/exec(2).

And example of the reverse popen(3) is here:

http://h30499.www3.hp.com/t5/Languages-and-Scripting/Facing-problem-with-popen-system-call-in-HP-UX/m-p/6566228#M47094

Re: C: How to pull in info from the system?

tony j. podrasky — Sat, 16 Aug 2014 23:03:59 GMT

Hello Dennis;

All I needed was the <popen> function.

Worked as expected.

Now I can re-write all the programs that I wrote that use [system abcdefg >> output] and then do an <open> of "output".

The link you left was a bonus!

Thank you for your help!

regards,

tonyp

Re: C: How to pull in info from the system?

Dennis Handly — Sun, 17 Aug 2014 01:27:52 GMT

>Thank you for your help!

If the posts were helpful, please click on the kudos stars, both here and at the link.