Function read_pid_file 

pub fn read_pid_file(path: &Path) -> Result<Option<u32>>

Read a process ID from a PID file, returning None if the file does not exist.

Args:

• path: Filesystem path of the PID file.

Usage:

if let Some(pid) = read_pid_file(&pid_path)? {
    println!("Agent running as PID {}", pid);
}