#include <unistd.h>

pid_t vfork(void);


Partially implemented


IEEE Std 1003.1, 2004


vfork() creates a new process; share virtual memory

The vfork() function shall be equivalent to fork(), except that the behavior is undefined if the process created by vfork() either modifies any data other than a variable of type pid_t used to store the return value from vfork(), or returns from the function in which vfork() was called, or calls any other function before successfully calling _exit() or one of the exec family of functions.

Return value#

Upon successful completion, vfork() shall return 0 to the child process and return the process ID of the child process to the parent process. Otherwise, -1 shall be returned to the parent, no child process shall be created, and errno shall be set to indicate the error.


The vfork() function shall fail if:

  • EAGAIN - The system-wide limit on the total number of processes under execution would be exceeded, or the system-imposed limit on the total number of processes under execution by a single user would be exceeded.

  • ENOMEM - There is insufficient swap space for the new process.



Known bugs#


See Also#

  1. Standard library functions

  2. Table of Contents