Output PID to file from process executed in bash script?

Question

I've got this simple bash script that starts a server process. I want to output the pid of the server process to a file, pid.txt . After some quick searching on SO, I came up with this approach, but it seems to give me the pid of the bash script, not the server process executed from the script. Note: the --fork is required for my server process to run as a daemon to output data to a separate log file, and I suspect that's causing the issue here based on this previous SO question , hoping there's a way around this.

#! /bin/bash

./mongo-linux64-202/mongod --fork &
pid=$!

printf "%s\n" "$pid" > pid.txt

Answer 1

Might I suggest:

#! /bin/bash

./mongo-linux64-202/mongod --pidfilepath ./pid.txt --fork &

derived from Mongo help:

mongod --help

Answer 2

./mongo-linux64-202/mongod --fork &
pid=$(jobs -p | tail -n 1)

Though look first whether mongod is willing to report its pid somehow.