Source code for pyworkflow.utils.which


# 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. "command" is a the name of the executable to search for. "path" is an optional alternate path list to search. The default it to use the PATH environment variable. "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. "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. 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. "command" is a the name of the executable to search for. "path" is an optional alternate path list to search. The default is to use the PATH environment variable. "verbose", if true, will cause a 2-tuple to be returned. The second element is a textual description of where the match was found. "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. 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. "command" is a the name of the executable to search for. "path" is an optional alternate path list to search. The default it to use the PATH environment variable. "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. "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))