Finding programs in PATH, adding shutil.which

[44e76c4e-f397-45e7-8e63-ae88bc35aef5]

BPO	444582
Nosy	@loewis, @birkenfeld, @abalkin, @pitrou, @vstinner, @giampaolo, @tiran, @devdanzin, @tarekziade, @merwok, @agbuckley, @bitdancer, @voidspace, @briancurtin, @petere, @sandrotosi, @takluyver
Files	find_in_path.py: Reference implementation of which and find_in_path (which anyone is free to use) shutil_which.patch: patch against 76432 which.py: Another reference implementation as a standalone module based on '2010-01-13 shutil_which.patch' with several fixes, mostly but not only for windows which.py: Updated version of reference implementation as a standalone module which.py: Updated version of reference implementation as a standalone module shutil_which_82778.patch: patch against 82778 which.py: updated reference implementation as a standalone module shutil_which_82778.patch: updated patch against 82778 which.py: updated reference implementation as a standalone module shutil_which_82778.patch: updated patch against 82778 which.py: updated reference implementation as a standalone module pathtest.bat: Batch file demonstrating Windows PATH behaviour with quoted paths issue444582.diff issue444582_v2.diff issue444582_v3.diff issue444582_v4.diff

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields: ```python assignee = 'https://github.com/briancurtin' closed_at = created_at = labels = ['type-feature', 'library'] title = 'Finding programs in PATH, adding shutil.which' updated_at = user = 'https://bugs.python.org/edemaine' ``` bugs.python.org fields: ```python activity = actor = 'eric.araujo' assignee = 'brian.curtin' closed = True closed_date = closer = 'eric.araujo' components = ['Library (Lib)'] creation = creator = 'edemaine' dependencies = [] files = ['8185', '15381', '16441', '16447', '16459', '17957', '17958', '17962', '17963', '18000', '18001', '23797', '26054', '26059', '26078', '26090'] hgrepos = [] issue_num = 444582 keywords = ['patch'] message_count = 61.0 messages = ['53174', '53175', '53176', '55402', '57774', '83484', '95614', '100444', '100460', '100469', '106046', '106055', '109234', '109554', '109583', '109587', '109764', '110033', '110034', '110049', '110068', '110073', '110084', '110085', '110291', '113241', '113285', '113944', '115016', '121398', '121424', '124996', '125222', '125233', '134306', '148475', '163201', '163242', '163253', '163376', '163454', '163466', '163479', '163481', '163482', '163483', '163484', '163485', '163487', '163488', '163490', '163492', '163493', '163764', '163800', '163802', '179889', '179891', '185218', '185220', '185221'] nosy_count = 31.0 nosy_names = ['loewis', 'tmick', 'georg.brandl', 'edemaine', 'belopolsky', 'pitrou', 'vstinner', 'wrstlprmpft', 'giampaolo.rodola', 'christian.heimes', 'ajaksu2', 'sfllaw', 'schmir', 'tarek', 'eric.araujo', 'Christophe Simonis', 'andybuckley', 'weeble', 'r.david.murray', 'tleeuwenburg@gmail.com', 'michael.foord', 'brian.curtin', 'meatballhat', 'petere', 'sandro.tosi', 'iki', 'BreamoreBoy', 'Iztok.Kavkler', 'python-dev', 'takluyver', 'Omega_Weapon'] pr_nums = [] priority = 'normal' resolution = 'fixed' stage = 'resolved' status = 'closed' superseder = None type = 'enhancement' url = 'https://bugs.python.org/issue444582' versions = ['Python 3.3'] ```

[bitdancer]

I'm fine with it changing. Hopefully it won't introduce subtle bugs in anyone's programs :)

[1762cc99-3127-4a62-9baf-30c3d0f51ef7]

New changeset 9d2fe615a400 by Antoine Pitrou in branch 'default': Issue bpo-444582: shutil.which() respects relative paths. http://hg.python.org/cpython/rev/9d2fe615a400

[pitrou]

There is another small issue: it returns the normcase'd dir, which means that the case is lost under Windows. Not very serious, but cosmetically imperfect I suppose.

[birkenfeld]

From 3.2, os has a function get_exec_path -- shouldn't which() use it instead of rolling its own query of $PATH?

[abalkin]

I don't think the Windows example in the reST documentation is correct:

      >>> print(shutil.which("python"))
      'c:\\python33\\python.exe'

It should be either

      >>> shutil.which("python")
      'c:\\python33\\python.exe'

or

      >>> print(shutil.which("python"))
      c:\python33\python.exe

[1762cc99-3127-4a62-9baf-30c3d0f51ef7]

New changeset 84b48551cd13 by Georg Brandl in branch 'default': bpo-444582: fix example and rewrap docs a bit. http://hg.python.org/cpython/rev/84b48551cd13

[cd34197f-d4a4-4e30-9fbe-454f267f097e]

The 'short circuit' appears to do what I'd consider the wrong thing when an executable file of the same name exists in the working directory. i.e. which('setup.py') can return 'setup.py', even though running 'setup.py' in a shell doesn't work (you need ./setup.py).

This is on UNIX-y systems, I see from the comments that the cwd is implicitly on the path in Windows.

Is this in scope for which() to deal with? Should I open a bug for it? Apologies if it's been discussed already.

[briancurtin]

Please open a separate issue.

[83d2e70e-e599-4a04-b820-3814bbdb9bef]

Was a separate issue opened? Is anything outstanding here or can this issue be closed?

[cd34197f-d4a4-4e30-9fbe-454f267f097e]

Yes, I opened that as bpo-16957, and it has been dealt with. So no objection from me to closing this.

[merwok]

It’s probably too late to address Georg’s comment about reusing os.get_exec_path, so everything is done.