alternatives of exec() system function Post: 302155102

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Top Forums Programming alternatives of exec() system function Post 302155102 by porter on Thursday 3rd of January 2008 01:27:57 AM

01-03-2008

Registered User

Quote:

Originally Posted by Raj Kumar Arora

And I dont want to create a new process in a thread.

The function system() takes a string which will be parsed by the shell, this can have as many arguments as the system will permit.

Under UNIX, the only way you can run a program is by "exec" which replaces the current program image with the new program.

If you want your program to continue running you have to call fork() or vfork() to create a new process, tough, but that is UNIX.

Yes, threads and fork can be a nightmare, what exactly is the problem? If it's resource contention/locking I suggest you have a look at "pthread_atfork()".

If you need to spawn a new process from a multithreaded program you have no options other than

(a) using fork/vfork
(b) calling a a function that wraps them up
(c) use IPC to talk to another program to create the new process

porter

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LEARN ABOUT BSD

fork

FORK(3F)																  FORK(3F)

NAME

       fork - create a copy of this process

SYNOPSIS

       integer function fork()

DESCRIPTION

       Fork  creates  a  copy  of  the	calling  process.   The only distinction between the 2 processes is that the value returned to one of them
       (referred to as the `parent' process) will be the process id of the copy.  The copy is usually referred to as  the  `child'  process.   The
       value returned to the `child' process will be zero.

       All logical units open for writing are flushed before the fork to avoid duplication of the contents of I/O buffers in the external file(s).

       If the returned value is negative, it indicates an error and will be the negation of the system error code.  See perror(3F).

       A corresponding exec routine has not been provided because there is no satisfactory way to retain open logical units across the exec.  How-
       ever, the usual function of fork/exec can be performed using system(3F).

FILES

       /usr/lib/libU77.a

SEE ALSO

       fork(2), wait(3F), kill(3F), system(3F), perror(3F)

4.2 Berkeley Distribution					   May 27, 1986 							  FORK(3F)

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