Getting a fully-qualified path from a PID

[Dan Nelson]

In the last episode (Jul 20), Joe Marcus Clarke said:
> What is the canonical way for a userland application to get the
> fully-qualified path of an executable from its running PID?  I know I
> can do a readlink(2) on /proc/pid/file, but procfs is deprecated on
> 5.X, correct?  Is there a more appropriate way to do this?  Thanks.

realpath(argv[0]) works for commands not run from $PATH. Commands found
through a PATH earch will just have the basename in argv[0] so you
would have to check each PATH element until you found it.  Note that
/proc/pid/file won't work if vn_fullpath() fails (say the orignal file
has been unlinked, or the filename has expired from the kernel's
cache).

If you are examining another process, you can use the kvm_getargv() and
kvm_getenvv() functions to fetch argv[0] and PATH out of the target
process.

-- 
	Dan Nelson
	dnelson at allantgroup.com