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# -*- coding: utf-8 -*-
__author__ = "Daniel Roy Greenfeld"
__email__ = "pydanny@gmail.com"
__version__ = "0.5.2"
import os
import sys
try: # Forced testing
from shutil import which
except ImportError: # Forced testing
# Versions prior to Python 3.3 don't have shutil.which
def which(cmd, mode=os.F_OK | os.X_OK, path=None):
"""Given a command, mode, and a PATH string, return the path which
conforms to the given mode on the PATH, or None if there is no such
file.
`mode` defaults to os.F_OK | os.X_OK. `path` defaults to the result
of os.environ.get("PATH"), or can be overridden with a custom search
path.
Note: This function was backported from the Python 3 source code.
"""
# Check that a given file can be accessed with the correct mode.
# Additionally check that `file` is not a directory, as on Windows
# directories pass the os.access check.
def _access_check(fn, mode):
return os.path.exists(fn) and os.access(fn, mode) and not os.path.isdir(fn)
# If we're given a path with a directory part, look it up directly
# rather than referring to PATH directories. This includes checking
# relative to the current directory, e.g. ./script
if os.path.dirname(cmd):
if _access_check(cmd, mode):
return cmd
return None
if path is None:
path = os.environ.get("PATH", os.defpath)
if not path:
return None
path = path.split(os.pathsep)
if sys.platform == "win32":
# The current directory takes precedence on Windows.
if os.curdir not in path:
path.insert(0, os.curdir)
# PATHEXT is necessary to check on Windows.
pathext = os.environ.get("PATHEXT", "").split(os.pathsep)
# See if the given file matches any of the expected path
# extensions. This will allow us to short circuit when given
# "python.exe". If it does match, only test that one, otherwise we
# have to try others.
if any(cmd.lower().endswith(ext.lower()) for ext in pathext):
files = [cmd]
else:
files = [cmd + ext for ext in pathext]
else:
# On other platforms you don't have things like PATHEXT to tell you
# what file suffixes are executable, so just pass on cmd as-is.
files = [cmd]
seen = set()
for dir in path:
normdir = os.path.normcase(dir)
if normdir not in seen:
seen.add(normdir)
for thefile in files:
name = os.path.join(dir, thefile)
if _access_check(name, mode):
return name
return None
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