Path: utzoo!utgpu!watserv1!watmath!iuvax!mailrus!uunet!virtech!cpcahil
From: cpcahil@virtech.uucp (Conor P. Cahill)
Newsgroups: comp.lang.c
Subject: Re: C-Execute-Command
Summary: RTFM
Message-ID: <1989Dec2.161237.23913@virtech.uucp>
Date: 2 Dec 89 16:12:37 GMT
References: <2615@servax0.essex.ac.uk>
Organization: Virtual Technologies Inc.
Lines: 37

In article <2615@servax0.essex.ac.uk>, georg@SunLab13.essex.ac.uk	 (Georgatos G) writes:
>             Does anybody know how to call an executable file from
>                                a c-program ?
>                       I am using the Unix-CC copiler.


Look up the word execute in the permuted index for you programmers reference
manual.  Therein you will find references to the exec(2) manual page.

If you want to use the simplest interface (but much less efficient and 
much more prone to security holes) you can use the system(3) library 
call (which for some reason is in the index as "issue a shell command" 
when it should be something like "execute commands using the shell" or 
some such thing).

All of the following will perform an "ls -l dir".  If you use one of the
exec()s you need to use fork() and wait() to run the  program as a sub-process.

		char 	*args[10];

		execl("/bin/ls","ls","-l","dir",(char *) 0);
		execlp("ls","ls","-l","dir",(char *) 0);

		args[0] = "ls", args[1] = "-l", args[2] = "dir", args[3] = NULL;

		execv("/bin/ls",args);
		execvp("ls",args);
		execvp(args[0],args);
		

		system("ls -l dir");

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