How to get the command line args passed to a running process on unix/linux systems?

There are several options:

ps -fp <pid>
cat /proc/<pid>/cmdline | sed -e "s/\x00/ /g"; echo

There is more info in /proc/<pid> on Linux, just have a look.

On other Unixes things might be different. The ps command will work everywhere, the /proc stuff is OS specific. For example on AIX there is no cmdline in /proc.

This will do the trick:

xargs -0 < /proc/<pid>/cmdline

Without the xargs, there will be no spaces between the arguments, because they have been converted to NULs.

Full commandline

For Linux & Unix System you can use ps -ef | grep process_name to get the full command line.

On SunOS systems, if you want to get full command line, you can use

/usr/ucb/ps -auxww | grep -i process_name

To get the full command line you need to become super user.

List of arguments

pargs -a PROCESS_ID

will give a detailed list of arguments passed to a process. It will output the array of arguments in like this:

argv[o]: first argument
argv[1]: second..
argv[*]: and so on..

I didn't find any similar command for Linux, but I would use the following command to get similar output:

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