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Greg Dubicki
Asked: 2014-06-01 07:34:07 +0800 CST

Is 'which' command always showing the right file / which binary is really being run?

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I am using Ubuntu 12.04 LTS and I have apparently messed up my system with various versions of duplicity installations:

  • first I had 0.6.18 installed from the default repo,
  • then I tried using 0.6.23 from the PPA
  • in the end I built 0.6.24 from the source and installed it

(I list this for completeness but I don't really think this is duplicity-specific.)

Now my system behaves like this:

root@host:~# duplicity -V
duplicity 0.6.24

root@host:~# which -a duplicity
/usr/bin/duplicity

root@host:~# /usr/bin/duplicity -V
duplicity 0.6.24

root@host:~# head /usr/bin/duplicity
#!/usr/bin/python2.7
# -*- Mode:Python; indent-tabs-mode:nil; tab-width:4 -*-
#
# duplicity -- Encrypted bandwidth efficient backup
# Version 0.6.23 released $reldate
#
# Copyright 2002 Ben Escoto <[email protected]>
# Copyright 2007 Kenneth Loafman <[email protected]>
#
# This file is part of duplicity.

???

Is there some kind of binary cache in Ubuntu that is being used here?

UPDATE:

root@host:~$ cat /usr/bin/duplicity | grep 24
            return 128 * 1024
    if maxopen < 1024:
        log.FatalError(_("Max open files of %s is too low, should be >= 1024.\n"
                         "Use 'ulimit -n 1024' or higher to correct.\n") % (maxopen,),
root@host:~$ cat /usr/bin/duplicity | grep 23
# Version 0.6.23 released $reldate
log.Log(u"duplicity 0.6.23 ($reldate)", verbosity)
bash

1 Answers

  1. Comments are often not in sync with the code. You could grep -F '0.6.24' /usr/bin/duplicity to check this. If that doesn't give any results, it could be that the version string is stored in multiple variables, so you might want to search for 23 or 24.

    As far as I know no distro has a cache of executables. I expect the security implications would be severe.

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