cpython/Lib/os.py

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"""OS routines for Mac, DOS, NT, or Posix depending on what system we're on.
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This exports:
- all functions from posix, nt, dos, os2, mac, or ce, e.g. unlink, stat, etc.
- os.path is one of the modules posixpath, ntpath, macpath, or dospath
- os.name is 'posix', 'nt', 'dos', 'os2', 'mac', or 'ce'
- os.curdir is a string representing the current directory ('.' or ':')
- os.pardir is a string representing the parent directory ('..' or '::')
- os.sep is the (or a most common) pathname separator ('/' or ':' or '\\')
- os.altsep is the alternate pathname separator (None or '/')
- os.pathsep is the component separator used in $PATH etc
- os.linesep is the line separator in text files ('\r' or '\n' or '\r\n')
- os.defpath is the default search path for executables
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Programs that import and use 'os' stand a better chance of being
portable between different platforms. Of course, they must then
only use functions that are defined by all platforms (e.g., unlink
and opendir), and leave all pathname manipulation to os.path
(e.g., split and join).
"""
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import sys
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_names = sys.builtin_module_names
altsep = None
if 'posix' in _names:
name = 'posix'
linesep = '\n'
curdir = '.'; pardir = '..'; sep = '/'; pathsep = ':'
defpath = ':/bin:/usr/bin'
from posix import *
try:
from posix import _exit
except ImportError:
pass
import posixpath
path = posixpath
del posixpath
elif 'nt' in _names:
name = 'nt'
linesep = '\r\n'
curdir = '.'; pardir = '..'; sep = '\\'; pathsep = ';'
defpath = '.;C:\\bin'
from nt import *
for i in ['_exit']:
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try:
exec "from nt import " + i
except ImportError:
pass
import ntpath
path = ntpath
del ntpath
elif 'dos' in _names:
name = 'dos'
linesep = '\r\n'
curdir = '.'; pardir = '..'; sep = '\\'; pathsep = ';'
defpath = '.;C:\\bin'
from dos import *
try:
from dos import _exit
except ImportError:
pass
import dospath
path = dospath
del dospath
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elif 'os2' in _names:
name = 'os2'
linesep = '\r\n'
curdir = '.'; pardir = '..'; sep = '\\'; pathsep = ';'
defpath = '.;C:\\bin'
from os2 import *
try:
from os2 import _exit
except ImportError:
pass
import ntpath
path = ntpath
del ntpath
elif 'mac' in _names:
name = 'mac'
linesep = '\r'
curdir = ':'; pardir = '::'; sep = ':'; pathsep = '\n'
defpath = ':'
from mac import *
try:
from mac import _exit
except ImportError:
pass
import macpath
path = macpath
del macpath
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elif 'ce' in _names:
name = 'ce'
linesep = '\r\n'
curdir = '.'; pardir = '..'; sep = '\\'; pathsep = ';'
defpath = '\\Windows'
from ce import *
for i in ['_exit']:
try:
exec "from ce import " + i
except ImportError:
pass
# We can use the standard Windows path.
import ntpath
path = ntpath
del ntpath
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else:
raise ImportError, 'no os specific module found'
del _names
sys.modules['os.path'] = path
# Super directory utilities.
# (Inspired by Eric Raymond; the doc strings are mostly his)
def makedirs(name, mode=0777):
"""makedirs(path [, mode=0777]) -> None
Super-mkdir; create a leaf directory and all intermediate ones.
Works like mkdir, except that any intermediate path segment (not
just the rightmost) will be created if it does not exist. This is
recursive.
"""
head, tail = path.split(name)
if not tail:
head, tail = path.split(head)
if head and tail and not path.exists(head):
makedirs(head, mode)
mkdir(name, mode)
def removedirs(name):
"""removedirs(path) -> None
Super-rmdir; remove a leaf directory and empty all intermediate
ones. Works like rmdir except that, if the leaf directory is
successfully removed, directories corresponding to rightmost path
segments will be pruned way until either the whole path is
consumed or an error occurs. Errors during this latter phase are
ignored -- they generally mean that a directory was not empty.
"""
rmdir(name)
head, tail = path.split(name)
if not tail:
head, tail = path.split(head)
while head and tail:
try:
rmdir(head)
except error:
break
head, tail = path.split(head)
def renames(old, new):
"""renames(old, new) -> None
Super-rename; create directories as necessary and delete any left
empty. Works like rename, except creation of any intermediate
directories needed to make the new pathname good is attempted
first. After the rename, directories corresponding to rightmost
path segments of the old name will be pruned way until either the
whole path is consumed or a nonempty directory is found.
Note: this function can fail with the new directory structure made
if you lack permissions needed to unlink the leaf directory or
file.
"""
head, tail = path.split(new)
if head and tail and not path.exists(head):
makedirs(head)
rename(old, new)
head, tail = path.split(old)
if head and tail:
try:
removedirs(head)
except error:
pass
# Make sure os.environ exists, at least
try:
environ
except NameError:
environ = {}
def execl(file, *args):
"""execl(file, *args)
Execute the executable file with argument list args, replacing the
current process. """
execv(file, args)
def execle(file, *args):
"""execle(file, *args, env)
Execute the executable file with argument list args and
environment env, replacing the current process. """
env = args[-1]
execve(file, args[:-1], env)
def execlp(file, *args):
"""execlp(file, *args)
Execute the executable file (which is searched for along $PATH)
with argument list args, replacing the current process. """
execvp(file, args)
def execlpe(file, *args):
"""execlpe(file, *args, env)
Execute the executable file (which is searched for along $PATH)
with argument list args and environment env, replacing the current
process. """
env = args[-1]
execvpe(file, args[:-1], env)
def execvp(file, args):
"""execp(file, args)
Execute the executable file (which is searched for along $PATH)
with argument list args, replacing the current process.
args may be a list or tuple of strings. """
_execvpe(file, args)
def execvpe(file, args, env):
"""execv(file, args, env)
Execute the executable file (which is searched for along $PATH)
with argument list args and environment env , replacing the
current process.
args may be a list or tuple of strings. """
_execvpe(file, args, env)
_notfound = None
def _execvpe(file, args, env=None):
if env is not None:
func = execve
argrest = (args, env)
else:
func = execv
argrest = (args,)
env = environ
global _notfound
head, tail = path.split(file)
if head:
apply(func, (file,) + argrest)
return
if env.has_key('PATH'):
envpath = env['PATH']
else:
envpath = defpath
PATH = envpath.split(pathsep)
if not _notfound:
import tempfile
# Exec a file that is guaranteed not to exist
try: execv(tempfile.mktemp(), ('blah',))
except error, _notfound: pass
exc, arg = error, _notfound
for dir in PATH:
fullname = path.join(dir, file)
try:
apply(func, (fullname,) + argrest)
except error, (errno, msg):
if errno != arg[0]:
exc, arg = error, (errno, msg)
raise exc, arg
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# Change environ to automatically call putenv() if it exists
try:
# This will fail if there's no putenv
putenv
except NameError:
pass
else:
import UserDict
if name in ('os2', 'nt', 'dos'): # Where Env Var Names Must Be UPPERCASE
# But we store them as upper case
class _Environ(UserDict.UserDict):
def __init__(self, environ):
UserDict.UserDict.__init__(self)
data = self.data
for k, v in environ.items():
data[k.upper()] = v
def __setitem__(self, key, item):
putenv(key, item)
self.data[key.upper()] = item
def __getitem__(self, key):
return self.data[key.upper()]
def __delitem__(self, key):
del self.data[key.upper()]
def has_key(self, key):
return self.data.has_key(key.upper())
def get(self, key, failobj=None):
return self.data.get(key.upper(), failobj)
def update(self, dict):
for k, v in dict.items():
self[k] = v
else: # Where Env Var Names Can Be Mixed Case
class _Environ(UserDict.UserDict):
def __init__(self, environ):
UserDict.UserDict.__init__(self)
self.data = environ
def __setitem__(self, key, item):
putenv(key, item)
self.data[key] = item
def update(self, dict):
for k, v in dict.items():
self[k] = v
environ = _Environ(environ)
def getenv(key, default=None):
"""Get an environment variable, return None if it doesn't exist.
The optional second argument can specify an alternative default."""
return environ.get(key, default)
def _exists(name):
try:
eval(name)
return 1
except NameError:
return 0
# Supply spawn*() (probably only for Unix)
if _exists("fork") and not _exists("spawnv") and _exists("execv"):
P_WAIT = 0
P_NOWAIT = P_NOWAITO = 1
# XXX Should we support P_DETACH? I suppose it could fork()**2
# and close the std I/O streams. Also, P_OVERLAY is the same
# as execv*()?
def _spawnvef(mode, file, args, env, func):
# Internal helper; func is the exec*() function to use
pid = fork()
if not pid:
# Child
try:
if env is None:
func(file, args)
else:
func(file, args, env)
except:
_exit(127)
else:
# Parent
if mode == P_NOWAIT:
return pid # Caller is responsible for waiting!
while 1:
wpid, sts = waitpid(pid, 0)
if WIFSTOPPED(sts):
continue
elif WIFSIGNALED(sts):
return -WTERMSIG(sts)
elif WIFEXITED(sts):
return WEXITSTATUS(sts)
else:
raise error, "Not stopped, signaled or exited???"
def spawnv(mode, file, args):
"""spawnv(mode, file, args) -> integer
Execute file with arguments from args in a subprocess.
If mode == P_NOWAIT return the pid of the process.
If mode == P_WAIT return the process's exit code if it exits normally;
otherwise return -SIG, where SIG is the signal that killed it. """
return _spawnvef(mode, file, args, None, execv)
def spawnve(mode, file, args, env):
"""spawnve(mode, file, args, env) -> integer
Execute file with arguments from args in a subprocess with the
specified environment.
If mode == P_NOWAIT return the pid of the process.
If mode == P_WAIT return the process's exit code if it exits normally;
otherwise return -SIG, where SIG is the signal that killed it. """
return _spawnvef(mode, file, args, env, execve)
# Note: spawnvp[e] is't currently supported on Windows
def spawnvp(mode, file, args):
"""spawnvp(mode, file, args) -> integer
Execute file (which is looked for along $PATH) with arguments from
args in a subprocess.
If mode == P_NOWAIT return the pid of the process.
If mode == P_WAIT return the process's exit code if it exits normally;
otherwise return -SIG, where SIG is the signal that killed it. """
return _spawnvef(mode, file, args, None, execvp)
def spawnvpe(mode, file, args, env):
"""spawnvpe(mode, file, args, env) -> integer
Execute file (which is looked for along $PATH) with arguments from
args in a subprocess with the supplied environment.
If mode == P_NOWAIT return the pid of the process.
If mode == P_WAIT return the process's exit code if it exits normally;
otherwise return -SIG, where SIG is the signal that killed it. """
return _spawnvef(mode, file, args, env, execvpe)
if _exists("spawnv"):
# These aren't supplied by the basic Windows code
# but can be easily implemented in Python
def spawnl(mode, file, *args):
"""spawnl(mode, file, *args) -> integer
Execute file with arguments from args in a subprocess.
If mode == P_NOWAIT return the pid of the process.
If mode == P_WAIT return the process's exit code if it exits normally;
otherwise return -SIG, where SIG is the signal that killed it. """
return spawnv(mode, file, args)
def spawnle(mode, file, *args):
"""spawnle(mode, file, *args, env) -> integer
Execute file with arguments from args in a subprocess with the
supplied environment.
If mode == P_NOWAIT return the pid of the process.
If mode == P_WAIT return the process's exit code if it exits normally;
otherwise return -SIG, where SIG is the signal that killed it. """
env = args[-1]
return spawnve(mode, file, args[:-1], env)
if _exists("spawnvp"):
# At the moment, Windows doesn't implement spawnvp[e],
# so it won't have spawnlp[e] either.
def spawnlp(mode, file, *args):
"""spawnlp(mode, file, *args, env) -> integer
Execute file (which is looked for along $PATH) with arguments from
args in a subprocess with the supplied environment.
If mode == P_NOWAIT return the pid of the process.
If mode == P_WAIT return the process's exit code if it exits normally;
otherwise return -SIG, where SIG is the signal that killed it. """
return spawnvp(mode, file, args)
def spawnlpe(mode, file, *args):
"""spawnlpe(mode, file, *args, env) -> integer
Execute file (which is looked for along $PATH) with arguments from
args in a subprocess with the supplied environment.
If mode == P_NOWAIT return the pid of the process.
If mode == P_WAIT return the process's exit code if it exits normally;
otherwise return -SIG, where SIG is the signal that killed it. """
env = args[-1]
return spawnvpe(mode, file, args[:-1], env)
if not _exists("popen2"):
def popen2(cmd, mode="t", bufsize=-1):
assert mode[:1] in ("b", "t")
import popen2
stdout, stdin = popen2.popen2(cmd, bufsize)
return stdin, stdout
if not _exists("popen3"):
def popen3(cmd, mode="t", bufsize=-1):
assert mode[:1] in ("b", "t")
import popen2
stdout, stdin, stderr = popen2.popen3(cmd, bufsize)
return stdin, stdout, stderr