SHELL

list the process id in linux

ps ux

bash get current process id

$! is the PID of the last backgrounded process.
kill -0 $PID checks whether it's still running.
$$ is the PID of the current shell.

how to check process id in linux

$ ps ax | grep firefox
2222 ?        S      0:00 /bin/sh /usr/lib/firefox-3.6.9/firefox
2231 ?        Sl   514:36 /usr/lib/firefox-3.6.9/firefox-bin
30290 pts/2    S+     0:00 grep --color=auto firefox

How to get process id

#include <iostream>
#include <Windows.h>
#include <tlhelp32.h>
#include <tchar.h>

std::uint32_t get_proc_id(const std::wstring& name)
{
	auto result = 0ul;
	auto snapshot = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);

	if (snapshot == INVALID_HANDLE_VALUE)
		return result;

	auto pe32w = PROCESSENTRY32W{};				// use the wide version of the struct
	pe32w.dwSize = sizeof(PROCESSENTRY32W);

	if (!Process32FirstW(snapshot, &pe32w))
		return CloseHandle(snapshot), result;

	while (Process32NextW(snapshot, &pe32w))
	{
		if (name == pe32w.szExeFile)			// use std::wstring's operator, not comparing pointers here
		{
			result = pe32w.th32ProcessID;
			break;
		}
	}

	CloseHandle(snapshot);
	return result;
}

int main()
{
	const auto pid = get_proc_id(L"explorer.exe");
	std::cout << pid;

	std::cin.get();
}

how to get process id in linux

lsof -i tcp:3000
kill -9 pId