[Linux 常見問題] Find out current working directory of a running process?

Source From Here
Question
What command(s) can one use to find out the current working directory (CWD) of a running process? These would be commands you could use externally from the process.

How-To
There are 3 methods that I'm aware of:
- pwdx: report current working directory of a process

// pwdx
# pwdx 16497
16497: /home/john/Tools/L2ParserSrv

- lsof: list open files of process

// -p s: excludes or selects the listing of files for the processes whose optional process IDentification (PID) numbers are in the comma-separated set s
# lsof -p 16497 | grep cwd
...
java 16497 root cwd DIR 253,2 4096 2149506102 /home/john/Tools/L2ParserSrv

- /proc

// -e, --canonicalize-existing: canonicalize by following every symlink in every component of the given name recursively, all components must exist
# readlink -e /proc/16497/cwd/
/home/john/Tools/L2ParserSrv