topic Re: The usage of function system() in UNIX in Operating System - Linux

The usage of function system() in UNIX

CA1490051 — Thu, 07 Jun 2007 23:57:32 GMT

Hi,

I dont kn ow this is is the right place to put this query. But, it will help me a lot if i can get the answer from any one of you.

Question is the system() builin function returns the integer value. But, i want to store the result of the command executed
ex- system("pwd"); in a string variable.
How can i achieve this?

thanks in advance
Vikram

Re: The usage of function system() in UNIX

Steven Schweda — Fri, 08 Jun 2007 00:46:28 GMT

Are you talking about system() in a C
program, or in a perl script, or where?

Re: The usage of function system() in UNIX

Dennis Handly — Fri, 08 Jun 2007 01:23:47 GMT

If this is a libc function, you must redirect stdout (system("pwd > file"). Or you can call popen(3). Or you should call getcwd(2)

If this is awk, you should pass PWD in its command line.

Re: The usage of function system() in UNIX

CA1490051 — Fri, 08 Jun 2007 05:16:12 GMT

Yes, I am talking about normal C- lib function.

Not any scripts.

thanks and regards
Vikram

Re: The usage of function system() in UNIX

Dennis Handly — Fri, 08 Jun 2007 05:21:01 GMT

>I am talking about normal C

Then you need to look into popen(3). That provides you with:
popen() creates a pipe between the calling program and a command to be executed by the POSIX shell

Then you just do fgets on the output.

Re: The usage of function system() in UNIX

A. Clay Stephenson — Fri, 08 Jun 2007 09:37:43 GMT

... and when you use popen(), you should also capture the return value of pclose() because that will return the exit status of the popen()'ed command --- equivalent to the value returned by system().

Re: The usage of function system() in UNIX

Sandman! — Fri, 08 Jun 2007 10:21:51 GMT

Check out the URL below for stuff relevant to your post:

http://www.opengroup.org/onlinepubs/009695399/functions/popen.html

Re: The usage of function system() in UNIX

dirk dierickx — Mon, 11 Jun 2007 07:02:12 GMT

in case this C program does very trivial stuff, i highly recommend writing this is perl...

Re: The usage of function system() in UNIX

CA1490051 — Mon, 11 Jun 2007 07:37:05 GMT

I have found the right solution for this by support of all of you.

thnaks and regards
Vikram