Environment variables of a running process on Unix?

I need to troubleshoot some problems related to environment variables on a Unix system.

On Windows, I can use a tool such as ProcessExplorer to select particular a process and view values of each environment variable.

How can I accomplish the same thing on Unix? echoing and env cmd just show values at present time, but I want to view what values the running process is using currently.

cat /proc/<pid>/environ

If you want to have pid(s) of a given running executable you can, among a number of other possibilities, use pidof:

AlberT$ pidof sshd   
30690 6512 

EDIT:

I totally quote Dennis Williamson and Teddy comments to achieve a more readable output. My solution is the following:

tr '\0' '\n' < /proc/<pid>/environ

Since this question has a unix tag and everyone else has done such a great job addressing linux tag, you can get this information on OS X and other BSD-derived systems using

ps -p <PID> -wwwe

or

ps -p <PID> -wwwE

and on Solaris with

/usr/ucb/ps -wwwe <PID>

Solaris also supports the /proc directory if you don't want to remember the obscure ps commmand.

As others have mentioned, on Linux, you can look in /proc but there are, depending on your kernel version, one or two limits:

First of all, the environ file contains the environment as it looked when the process was spawned. That means that any changes the process might have made to its environment will not be visible in /proc:

$ cat /proc/$$/environ | wc -c
320
$ bash
$ cat /proc/$$/environ | wc -c
1270
$ 

The first shell is a login shell and initially has a very limited environment but grows it by sourcing e.g. .bashrc but /proc does not reflect this. The second shell inherits the larger environment from the start, which it why it shows in /proc.

Also, on older kernels, the contents of the environ file is limited to a page size (4K):

$ cat /proc/$$/environ | wc -c
4096
$ env | wc -c
10343
$ 

Somewhere between 2.6.9 (RHEL4) and 2.6.18 (RHEL5) this limit was removed...