I want to check if a process is running or not. I've been trying by 

```
ps -C /path/file

```

and get this response:

```
PID TTY          TIME CMD

```

If I do 

```
pgrep php

```

I get a list of php processes running, but only the PID.

Is there a possibility to 

* determine the PID of a file I specify (I want to type the file and get the PID)
* get the filename if I type the PID
* get all the running processes PIDs in a file to work with that in a later script

*OS:* *Ubuntu 14.04 LTS*

I've been looking for this since quite some time, tried all the possibilities I found on SO and else but just can't figure out how to do this best.