# Copyright (c) 2002-2005 ActiveState Corp.
# See LICENSE.txt for license details.
# Author:
# Trent Mick (TrentM@ActiveState.com)
# Home:
# http://trentm.com/projects/which/
"""Find the full path to commands.
which(command, path=None, verbose=0, exts=None)
Return the full path to the first match of the given command on the
path.
whichall(command, path=None, verbose=0, exts=None)
Return a list of full paths to all matches of the given command on
the path.
whichgen(command, path=None, verbose=0, exts=None)
Return a generator which will yield full paths to all matches of the
given command on the path.
"""
import os
import sys
import stat
# ---- exceptions
[docs]class WhichError(Exception):
pass
# ---- internal support stuff
def _getRegisteredExecutable(exeName):
"""Windows allow application paths to be registered in the registry."""
registered = None
if sys.platform.startswith('win'):
if os.path.splitext(exeName)[1].lower() != '.exe':
exeName += '.exe'
import winreg
try:
key = "SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\App Paths\\" +\
exeName
value = winreg.QueryValue(winreg.HKEY_LOCAL_MACHINE, key)
registered = (value, "from HKLM\\"+key)
except winreg.error:
pass
if registered and not os.path.exists(registered[0]):
registered = None
return registered
def _samefile(fname1, fname2):
if sys.platform.startswith('win'):
return (os.path.normpath(os.path.normcase(fname1)) ==
os.path.normpath(os.path.normcase(fname2)))
else:
return os.path.samefile(fname1, fname2)
def _cull(potential, matches, verbose=0):
"""Cull inappropriate matches. Possible reasons:
- a duplicate of a previous match
- not a disk file
- not executable (non-Windows)
If 'potential' is approved it is returned and added to 'matches'.
Otherwise, None is returned.
"""
for match in matches: # don't yield duplicates
if _samefile(potential[0], match[0]):
if verbose:
sys.stderr.write("duplicate: %s (%s)\n" % potential)
return None
else:
if not stat.S_ISREG(os.stat(potential[0]).st_mode):
if verbose:
sys.stderr.write("not a regular file: %s (%s)\n" % potential)
elif not os.access(potential[0], os.X_OK):
if verbose:
sys.stderr.write("no executable access: %s (%s)\n"
% potential)
else:
matches.append(potential)
return potential
# ---- module API
[docs]def whichgen(command, path=None, verbose=0, exts=None):
"""Return a generator of full paths to the given command.
:param command: is a the name of the executable to search for.
:param path: is an optional alternate path list to search. The default it
to use the PATH environment variable.
:param verbose: if true, will cause a 2-tuple to be returned for each
match. The second element is a textual description of where the
match was found.
:param exts: optionally allows one to specify a list of extensions to use
instead of the standard list for this system. This can
effectively be used as an optimization to, for example, avoid
stat's of "foo.vbs" when searching for "foo" and you know it is
not a VisualBasic script but ".vbs" is on PATHEXT. This option
is only supported on Windows.
:return: This method returns a generator which yields either full paths to
the given command or, if verbose, tuples of the form (<path to
command>, <where path found>).
"""
matches = []
if path is None:
usingGivenPath = 0
path = os.environ.get("PATH", "").split(os.pathsep)
if sys.platform.startswith("win"):
path.insert(0, os.curdir) # implied by Windows shell
else:
usingGivenPath = 1
# Windows has the concept of a list of extensions (PATHEXT env var).
if sys.platform.startswith("win"):
if exts is None:
exts = os.environ.get("PATHEXT", "").split(os.pathsep)
# If '.exe' is not in exts then obviously this is Win9x and
# or a bogus PATHEXT, then use a reasonable default.
for ext in exts:
if ext.lower() == ".exe":
break
else:
exts = ['.COM', '.EXE', '.BAT']
elif not isinstance(exts, list):
raise TypeError("'exts' argument must be a list or None")
else:
if exts is not None:
raise WhichError("'exts' argument is not supported on "
"platform '%s'" % sys.platform)
exts = []
# File name cannot have path separators because PATH lookup does not
# work that way.
if os.sep in command or os.altsep and os.altsep in command:
pass
else:
for i in range(len(path)):
dirName = path[i]
# On windows the dirName *could* be quoted, drop the quotes
if sys.platform.startswith("win") and len(dirName) >= 2\
and dirName[0] == '"' and dirName[-1] == '"':
dirName = dirName[1:-1]
for ext in ['']+exts:
absName = os.path.abspath(
os.path.normpath(os.path.join(dirName, command+ext)))
if os.path.isfile(absName):
if usingGivenPath:
fromWhere = "from given path element %d" % i
elif not sys.platform.startswith("win"):
fromWhere = "from PATH element %d" % i
elif i == 0:
fromWhere = "from current directory"
else:
fromWhere = "from PATH element %d" % (i-1)
match = _cull((absName, fromWhere), matches, verbose)
if match:
if verbose:
yield match
else:
yield match[0]
match = _getRegisteredExecutable(command)
if match is not None:
match = _cull(match, matches, verbose)
if match:
if verbose:
yield match
else:
yield match[0]
[docs]def which(command, path=None, verbose=0, exts=None):
"""Return the full path to the first match of the given command on
the path.
:param command: is a the name of the executable to search for.
:param path: is an optional alternate path list to search.
The default is to use the PATH environment variable.
:param verbose: if true, will cause a 2-tuple to be returned.
The second element is a textual description of where the match was found.
:param exts: optionally allows one to specify a list of extensions to use
instead of the standard list for this system. This can
effectively be used as an optimization to, for example, avoid
stat's of "foo.vbs" when searching for "foo" and you know it is
not a VisualBasic script but ".vbs" is on PATHEXT. This option
is only supported on Windows.
:return If no match is found for the command, an empty string is returned.
"""
try:
match = next(whichgen(command, path, verbose, exts))
except StopIteration:
return ''
return match
[docs]def commandExists(command):
path = which(command)
return path != ''
[docs]def whichall(command, path=None, verbose=0, exts=None):
"""Return a list of full paths to all matches of the given command
on the path.
:param command: is a the name of the executable to search for.
:param path: is an optional alternate path list to search. The default it
to use the PATH environment variable.
:param verbose: if true, will cause a 2-tuple to be returned for each
match. The second element is a textual description of where the
match was found.
:param exts: optionally allows one to specify a list of extensions to use
instead of the standard list for this system. This can
effectively be used as an optimization to, for example, avoid
stat's of "foo.vbs" when searching for "foo" and you know it is
not a VisualBasic script but ".vbs" is on PATHEXT. This option
is only supported on Windows.
"""
return list(whichgen(command, path, verbose, exts))