CODEWITHSUNDEEP
linuxoperating-systemexec
mainajaved
mainajaved

Reputation: 8173

Simple exec program in linux

Hello every one I want to ask a question that what is "simple exec" I have heard it some where and I have searched for it but don't get any useful answer can any one tell me

Thanks in advance

Upvotes: 0

Views: 1215

Answers (2)

Xander
Xander

Reputation: 1715

There are exec functions in all programming languages. These are methods used to invoke the system shell/cmd in from a program.

exec functions are dangerous since they are directly interacting with the OS from external.

Upvotes: 0

Guido
Guido

Reputation: 2634

An exec system call replaces your current running process with some program stored in disk. It only keeps the system segment of the original process (meaning: PID, file descriptors, and other system stuff) It is provided by the Linux/Unix kernel and there are several ways to call it, check the various exec definitions according to POSIX in http://pubs.opengroup.org/onlinepubs/009604499/functions/exec.html. A simple demostration program would be:

#include <unistd.h>
#include <stdio.h>

int main()
{
    printf("Giving control to ls!\n");
    execl("/usr/bin/ls","ls",NULL);
    printf("This should never be printed..\n");
    return 0;
}

That program prints a line and executes 'ls', so you would see the message, then the output of ls, and that's it. The last line isn't displayed because your process was replaced.

Upvotes: 2

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