Find location where process started from on linux

If I have output from ps like the following, is there any way to determine where 'blah' is on the file system? For my particular situation, the -p specifies which port the application should run on.

user 22913 22470  0 09:58 ?        00:00:06 ./blah -p 12345

My question is basically whether or not it is possible to find the location of an executable given the PID or port of the application. The distro being used is Redhat.

From serverfault bcasp

• Do any of these give information?

  ps -ef

  ps -eLf

  ps axms

  Or maybe

  ps -o cmd= -p $PID

  This might be more useful:

  readlink -f /proc/$PID/exe

  ?

  bcasp : readlink just echoes back what the input is on the system I'm using. The other commands give me back the ./blah instead of the /abc/def/blah I'm looking for.

  Bart Silverstrim : What do you mean by the input the system is using? bsilver@desktop:~$ ps PID TTY TIME CMD 29626 pts/3 00:00:00 bash 29644 pts/3 00:00:00 ps bsilver@desktop:~$ readlink -f /proc/29626/exe /bin/bash bsilver@desktop:~$

  Bart Silverstrim : Whoops didn't format that right...but it did show that ps was saying "bash" but readlink for that PID said /bin/bash is the executable path.

  Bart Silverstrim : The command I used was "readlink -f /proc/29626/exe" to get that pathname.

  bcasp : Sorry. It was because the user I was logged on as didn't have permissions. readlink is exactly what I was looking for.

  Bart Silverstrim : You are welcome :-)
  From Bart Silverstrim

• Like Bart suggested,

  readlink -f /proc/$PID/exe
  

  shoud give you your answer.

  From Raphink

• To build on the readlink stuff, another way might be readlink -f /proc/$PID/cwd. This will display the Current Working Directory of a process, which can be handy if you've executed a bash script, since the exe link is then /bin/bash, with an argument of ./blah.

  And as a bit more random information, you can just cd to /proc/$PID. There will be symlinks for cwd and exe, as mentioned, as well as where that processes root directory is (useful if chrooted) ls -l will show where these are pointing, which is essentially what readlink is doing.

  From Christopher Karel

• sudo /usr/sbin/lsof -p 22913

  From cagenut

• If you want the current directory based on the server port currently in use, you can try

  readlink -f /proc/$(lsof -ti :"port number")/cwd
  

  lsof in terse mode (-t) will dump only the pid, of the process owning the internet server socket (-i :port_number), and then you fall back in the other proposal using /proc to get the current working directory out of a pid.

  From Zeograd