When debugging or monitoring processes in macOS, developers often need to map Process IDs (PIDs) back to their original executable paths. While ps provides comprehensive process information, it doesn't directly display the full executable path in its default output.

macOS provides several methods to extract this information:

# Method 1: Using ps with custom formatting
ps -p [PID] -o comm=

# Method 2: The procpidinfo approach
procpidinfo [PID] vnodeinfo

# Method 3: System call through Python
import os
print(os.readlink(f"/proc/{PID}/file"))

For most reliable results across macOS versions:

# Using sysctl to get full process path
sysctl -n kern.proc.pid.[PID] | awk '/proc_name/ {print $2}'

# More detailed C implementation:
#include 
#include 

void getExecPath(pid_t pid) {
    int mib[4] = { CTL_KERN, KERN_PROCARGS2, pid };
    char buffer[1024];
    size_t size = sizeof(buffer);
    sysctl(mib, 3, buffer, &size, NULL, 0);
    printf("%s\n", buffer+sizeof(int));
}

Here's a complete Swift implementation:

import Foundation

func getProcessPath(pid: pid_t) -> String? {
    var mib = [CTL_KERN, KERN_PROCARGS2, pid]
    var size = 0
    
    guard sysctl(&mib, 3, nil, &size, nil, 0) == 0 else { return nil }
    
    var buffer = [CChar](repeating: 0, count: size)
    guard sysctl(&mib, 3, &buffer, &size, nil, 0) == 0 else { return nil }
    
    return String(cString: buffer + MemoryLayout.size)
}

For specialized cases:

# lsof approach (requires root for some processes)
lsof -p [PID] | grep txt | awk '{print $9}'

# dtrace one-liner
dtrace -n 'syscall::exec*:return { printf("%s %s", execname, copyinstr(arg0)); }'

When implementing process monitoring:

• sysctl calls are fastest for single lookups
• proc_pidinfo provides most detailed information
• lsof has highest overhead but works for zombie processes

Remember that:

• Process paths can be spoofed by advanced malware
• Some system processes may return empty paths
• Sandboxed apps may restrict access to this information

When working with process management in macOS (or any UNIX-like system), there are several robust methods to get the executable path from a process ID (PID). While ps provides basic process information, it doesn't always show the full executable path.

The simplest approach is to use ps with the -o flag to specify output format:

ps -p PID -o comm=

For full path:

ps -p PID -o command=

macOS doesn't mount procfs by default, but you can use the proc_pidpath API:

#include 
#include 

int main(int argc, char *argv[]) {
    pid_t pid = atoi(argv[1]);
    char pathbuf[PROC_PIDPATHINFO_MAXSIZE];
    
    if (proc_pidpath(pid, pathbuf, sizeof(pathbuf)) <= 0) {
        fprintf(stderr, "Error getting path for PID %d\n", pid);
        return 1;
    }
    
    printf("%s\n", pathbuf);
    return 0;
}

Another reliable method is using lsof:

lsof -p PID | grep txt | awk '{print $9}'

For programmatic access in Swift/Objective-C:

import Foundation

func getProcessPath(pid: pid_t) -> String? {
    let pathBuffer = UnsafeMutablePointer.allocate(capacity: Int(PROC_PIDPATHINFO_MAXSIZE))
    defer { pathBuffer.deallocate() }
    
    let ret = proc_pidpath(pid, pathBuffer, UInt32(PROC_PIDPATHINFO_MAXSIZE))
    if ret <= 0 {
        return nil
    }
    
    return String(cString: pathBuffer)
}

Be aware that some system processes might return empty paths or special markers. Kernel extensions and system daemons often have special handling requirements.

For frequent polling, the C API (proc_pidpath) is fastest, while shell commands add significant overhead. When building performance-sensitive tools, prefer direct system calls.