Re: Getting a fully-qualified path from a PID

From: Joe Marcus Clarke (marcus_at_marcuscom.com)
Date: 07/21/04

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    To: Dan Nelson <dnelson@allantgroup.com>
Date: Wed, 21 Jul 2004 12:27:13 -0400

    On Wed, 2004-07-21 at 11:12, Dan Nelson wrote:
    > 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.

    Okay, I was thinking about that. What I was specifically interested in
    was processes spawned from $PATH, so realpath isn't going to be much
    good to me there. I didn't know if there was a better way than getting
    the environ+argv with kvm, then searching each path element. Thanks for
    the clarification.

    Joe 

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