#daemon-process #process #daemon #daemonize #setsid

fork

Library for creating a new process detached from the controlling terminal (daemon)

24 releases

0.1.23 Feb 1, 2024
0.1.22 Jun 6, 2023
0.1.21 Mar 12, 2023
0.1.20 Aug 23, 2022
0.1.9 Oct 28, 2019

#40 in Operating systems

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65,732 downloads per month
Used in 25 crates (24 directly)

BSD-3-Clause

10KB
73 lines

fork

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Library for creating a new process detached from the controlling terminal (daemon).

Why?

  • Minimal library to daemonize, fork, double-fork a process.
  • daemon(3) has been deprecated in MacOSX 10.5, by using fork and setsid syscalls, new methods can be created to achieve the same goal.

Example:

Create a new test project:

$ cargo new --bin fork

To install cargo use: curl https://sh.rustup.rs -sSf | sh

Edit fork/Cargo.toml and add to [dependencies]:

fork = "0.1"

Add the following code to fork/main.rs

use fork::{daemon, Fork};
use std::process::Command;

fn main() {
    if let Ok(Fork::Child) = daemon(false, false) {
        Command::new("sleep")
            .arg("300")
            .output()
            .expect("failed to execute process");
    }
}

If using daemon(false, false),it will chdir to / and close the standard input, standard output, and standard error file descriptors.

Test running:

$ cargo run

Use ps to check the process, for example:

$ ps -axo ppid,pid,pgid,sess,tty,tpgid,stat,uid,%mem,%cpu,command, | egrep "fork|sleep|PID"

egrep is used to show the ps headers

Output should be something like:

 PPID   PID  PGID   SESS TTY      TPGID STAT   UID       %MEM  %CPU COMMAND
    1 48738 48737      0 ??           0 S      501        0.0   0.0 target/debug/fork
48738 48753 48737      0 ??           0 S      501        0.0   0.0 sleep 300
  • PPID == 1 that's the parent process

  • TTY = ?? no controlling terminal

  • new PGID = 48737

    1 - root (init/launchd)
     \-- 48738 fork         PGID - 48737
      \--- 48753 sleep      PGID - 48737
    

Dependencies

~43KB