creating process

[maggi]

hi all

i am new to linux programming.
actually i need to start a new process within a process.i dont want to use fork().
can any one tell me is there any system call that creates a new process and returns pid of the created process. i can start a process by system() but the calling process will be blocked untill that process completes . i dont want my calling process to get blocked but has to start a new process.

[Lakshmipathi]

can start a process by system()

Have you tried exec functions family Fork, Exec and Process control

i dont want to use fork().

I believe fork() will be invoked internally by all system calls
to creat a new process.

[WuNMOjTIQanXWBcH]

Answer:

i need to start a new process within a process.i dont want to use fork().
can any one tell me is there any system call that creates a new process and returns pid of the created process.

The only calls I know of that start new processes are:

• fork
  
• clone
  
• posix_spawn

While the first two are both library function and syscalls, I believe the third is implementation dependent (as to which syscall it uses).

I believe fork() will be invoked internally by all system calls
to creat a new process.

Syscalls are a kernel-userspace-gate interface. While a syscall is invoked, the process runs in kernel mode and can do whatever it wants (within the parameters of the syscall, of course). Thereʼs no need to invoke another syscall.

Question:
maggi: Care to explain why you donʼt want to use «fork()»?