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Python module – os

| January 18, 2013 | 0 Comments
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NAME
os – OS routines for Mac, NT, or Posix depending on what system we’re on.

FILE
c:\python27\lib\os.py

DESCRIPTION
This exports:
– all functions from posix, nt, os2, or ce, e.g. unlink, stat, etc.
– os.path is one of the modules posixpath, or ntpath
– os.name is ‘posix’, ‘nt’, ‘os2’, ‘ce’ or ‘riscos’
– 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.extsep is the extension separator (‘.’ 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
– os.devnull is the file path of the null device (‘/dev/null’, etc.)

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).

CLASSES
__builtin__.object
nt.stat_result
nt.statvfs_result
exceptions.EnvironmentError(exceptions.StandardError)
exceptions.OSError

error = class OSError(EnvironmentError)
| OS system call failed.
|
| Method resolution order:
| OSError
| EnvironmentError
| StandardError
| Exception
| BaseException
| __builtin__.object
|
| Methods defined here:
|
| __init__(…)
| x.__init__(…) initializes x; see help(type(x)) for signature
|
| ———————————————————————-
| Data and other attributes defined here:
|
| __new__ = <built-in method __new__ of type object>
| T.__new__(S, …) -> a new object with type S, a subtype of T
|
| ———————————————————————-
| Methods inherited from EnvironmentError:
|
| __reduce__(…)
|
| __str__(…)
| x.__str__() <==> str(x)
|
| ———————————————————————-
| Data descriptors inherited from EnvironmentError:
|
| errno
| exception errno
|
| filename
| exception filename
|
| strerror
| exception strerror
|
| ———————————————————————-
| Methods inherited from BaseException:
|
| __delattr__(…)
| x.__delattr__(‘name’) <==> del x.name
|
| __getattribute__(…)
| x.__getattribute__(‘name’) <==> x.name
|
| __getitem__(…)
| x.__getitem__(y) <==> x[y] |
| __getslice__(…)
| x.__getslice__(i, j) <==> x[i:j] |
| Use of negative indices is not supported.
|
| __repr__(…)
| x.__repr__() <==> repr(x)
|
| __setattr__(…)
| x.__setattr__(‘name’, value) <==> x.name = value
|
| __setstate__(…)
|
| __unicode__(…)
|
| ———————————————————————-
| Data descriptors inherited from BaseException:
|
| __dict__
|
| args
|
| message

class stat_result(__builtin__.object)
| stat_result: Result from stat or lstat.
|
| This object may be accessed either as a tuple of
| (mode, ino, dev, nlink, uid, gid, size, atime, mtime, ctime)
| or via the attributes st_mode, st_ino, st_dev, st_nlink, st_uid, and so on.
|
| Posix/windows: If your platform supports st_blksize, st_blocks, st_rdev,
| or st_flags, they are available as attributes only.
|
| See os.stat for more information.
|
| Methods defined here:
|
| __add__(…)
| x.__add__(y) <==> x+y
|
| __contains__(…)
| x.__contains__(y) <==> y in x
|
| __eq__(…)
| x.__eq__(y) <==> x==y
|
| __ge__(…)
| x.__ge__(y) <==> x>=y
|
| __getitem__(…)
| x.__getitem__(y) <==> x[y] |
| __getslice__(…)
| x.__getslice__(i, j) <==> x[i:j] |
| Use of negative indices is not supported.
|
| __gt__(…)
| x.__gt__(y) <==> x>y
|
| __hash__(…)
| x.__hash__() <==> hash(x)
|
| __le__(…)
| x.__le__(y) <==> x<=y
|
| __len__(…)
| x.__len__() <==> len(x)
|
| __lt__(…)
| x.__lt__(y) <==> x<y
|
| __mul__(…)
| x.__mul__(n) <==> x*n
|
| __ne__(…)
| x.__ne__(y) <==> x!=y
|
| __reduce__(…)
|
| __repr__(…)
| x.__repr__() <==> repr(x)
|
| __rmul__(…)
| x.__rmul__(n) <==> n*x
|
| ———————————————————————-
| Data descriptors defined here:
|
| st_atime
| time of last access
|
| st_ctime
| time of last change
|
| st_dev
| device
|
| st_gid
| group ID of owner
|
| st_ino
| inode
|
| st_mode
| protection bits
|
| st_mtime
| time of last modification
|
| st_nlink
| number of hard links
|
| st_size
| total size, in bytes
|
| st_uid
| user ID of owner
|
| ———————————————————————-
| Data and other attributes defined here:
|
| __new__ = <built-in method __new__ of type object>
| T.__new__(S, …) -> a new object with type S, a subtype of T
|
| n_fields = 13
|
| n_sequence_fields = 10
|
| n_unnamed_fields = 3

class statvfs_result(__builtin__.object)
| statvfs_result: Result from statvfs or fstatvfs.
|
| This object may be accessed either as a tuple of
| (bsize, frsize, blocks, bfree, bavail, files, ffree, favail, flag, namemax),
| or via the attributes f_bsize, f_frsize, f_blocks, f_bfree, and so on.
|
| See os.statvfs for more information.
|
| Methods defined here:
|
| __add__(…)
| x.__add__(y) <==> x+y
|
| __contains__(…)
| x.__contains__(y) <==> y in x
|
| __eq__(…)
| x.__eq__(y) <==> x==y
|
| __ge__(…)
| x.__ge__(y) <==> x>=y
|
| __getitem__(…)
| x.__getitem__(y) <==> x[y] |
| __getslice__(…)
| x.__getslice__(i, j) <==> x[i:j] |
| Use of negative indices is not supported.
|
| __gt__(…)
| x.__gt__(y) <==> x>y
|
| __hash__(…)
| x.__hash__() <==> hash(x)
|
| __le__(…)
| x.__le__(y) <==> x<=y
|
| __len__(…)
| x.__len__() <==> len(x)
|
| __lt__(…)
| x.__lt__(y) <==> x<y
|
| __mul__(…)
| x.__mul__(n) <==> x*n
|
| __ne__(…)
| x.__ne__(y) <==> x!=y
|
| __reduce__(…)
|
| __repr__(…)
| x.__repr__() <==> repr(x)
|
| __rmul__(…)
| x.__rmul__(n) <==> n*x
|
| ———————————————————————-
| Data descriptors defined here:
|
| f_bavail
|
| f_bfree
|
| f_blocks
|
| f_bsize
|
| f_favail
|
| f_ffree
|
| f_files
|
| f_flag
|
| f_frsize
|
| f_namemax
|
| ———————————————————————-
| Data and other attributes defined here:
|
| __new__ = <built-in method __new__ of type object>
| T.__new__(S, …) -> a new object with type S, a subtype of T
|
| n_fields = 10
|
| n_sequence_fields = 10
|
| n_unnamed_fields = 0

FUNCTIONS
abort(…)
abort() -> does not return!

Abort the interpreter immediately. This ‘dumps core’ or otherwise fails
in the hardest way possible on the hosting operating system.

access(…)
access(path, mode) -> True if granted, False otherwise

Use the real uid/gid to test for access to a path. Note that most
operations will use the effective uid/gid, therefore this routine can
be used in a suid/sgid environment to test if the invoking user has the
specified access to the path. The mode argument can be F_OK to test
existence, or the inclusive-OR of R_OK, W_OK, and X_OK.

chdir(…)
chdir(path)

Change the current working directory to the specified path.

chmod(…)
chmod(path, mode)

Change the access permissions of a file.

close(…)
close(fd)

Close a file descriptor (for low level IO).

closerange(…)
closerange(fd_low, fd_high)

Closes all file descriptors in [fd_low, fd_high), ignoring errors.

dup(…)
dup(fd) -> fd2

Return a duplicate of a file descriptor.

dup2(…)
dup2(old_fd, new_fd)

Duplicate file descriptor.

execl(file, *args)
execl(file, *args)

Execute the executable file with argument list args, replacing the
current process.

execle(file, *args)
execle(file, *args, env)

Execute the executable file with argument list args and
environment env, replacing the current process.

execlp(file, *args)
execlp(file, *args)

Execute the executable file (which is searched for along $PATH)
with argument list args, replacing the current process.

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.

execv(…)
execv(path, args)

Execute an executable path with arguments, replacing current process.

path: path of executable file
args: tuple or list of strings

execve(…)
execve(path, args, env)

Execute a path with arguments and environment, replacing current process.

path: path of executable file
args: tuple or list of arguments
env: dictionary of strings mapping to strings

execvp(file, args)
execvp(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, env)
execvpe(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.

fdopen(…)
fdopen(fd [, mode=’r’ [, bufsize]]) -> file_object

Return an open file object connected to a file descriptor.

fstat(…)
fstat(fd) -> stat result

Like stat(), but for an open file descriptor.

fsync(…)
fsync(fildes)

force write of file with filedescriptor to disk.

getcwd(…)
getcwd() -> path

Return a string representing the current working directory.

getcwdu(…)
getcwdu() -> path

Return a unicode string representing the current working directory.

getenv(key, default=None)
Get an environment variable, return None if it doesn’t exist.
The optional second argument can specify an alternate default.

getpid(…)
getpid() -> pid

Return the current process id

isatty(…)
isatty(fd) -> bool

Return True if the file descriptor ‘fd’ is an open file descriptor
connected to the slave end of a terminal.

kill(…)
kill(pid, sig)

Kill a process with a signal.

listdir(…)
listdir(path) -> list_of_strings

Return a list containing the names of the entries in the directory.

path: path of directory to list

The list is in arbitrary order. It does not include the special
entries ‘.’ and ‘..’ even if they are present in the directory.

lseek(…)
lseek(fd, pos, how) -> newpos

Set the current position of a file descriptor.

lstat(…)
lstat(path) -> stat result

Like stat(path), but do not follow symbolic links.

makedirs(name, mode=511)
makedirs(path [, mode=0777])

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.

mkdir(…)
mkdir(path [, mode=0777])

Create a directory.

open(…)
open(filename, flag [, mode=0777]) -> fd

Open a file (for low level IO).

pipe(…)
pipe() -> (read_end, write_end)

Create a pipe.

popen(…)
popen(command [, mode=’r’ [, bufsize]]) -> pipe

Open a pipe to/from a command returning a file object.

popen2(…)

popen3(…)

popen4(…)

putenv(…)
putenv(key, value)

Change or add an environment variable.

read(…)
read(fd, buffersize) -> string

Read a file descriptor.

remove(…)
remove(path)

Remove a file (same as unlink(path)).

removedirs(name)
removedirs(path)

Super-rmdir; remove a leaf directory and all empty intermediate
ones. Works like rmdir except that, if the leaf directory is
successfully removed, directories corresponding to rightmost path
segments will be pruned away 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.

rename(…)
rename(old, new)

Rename a file or directory.

renames(old, new)
renames(old, new)

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.

rmdir(…)
rmdir(path)

Remove a directory.

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.

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.

spawnv(…)
spawnv(mode, path, args)

Execute the program ‘path’ in a new process.

mode: mode of process creation
path: path of executable file
args: tuple or list of strings

spawnve(…)
spawnve(mode, path, args, env)

Execute the program ‘path’ in a new process.

mode: mode of process creation
path: path of executable file
args: tuple or list of arguments
env: dictionary of strings mapping to strings

startfile(…)
startfile(filepath [, operation]) – Start a file with its associated
application.

When “operation” is not specified or “open”, this acts like
double-clicking the file in Explorer, or giving the file name as an
argument to the DOS “start” command: the file is opened with whatever
application (if any) its extension is associated.
When another “operation” is given, it specifies what should be done with
the file. A typical operation is “print”.

startfile returns as soon as the associated application is launched.
There is no option to wait for the application to close, and no way
to retrieve the application’s exit status.

The filepath is relative to the current directory. If you want to use
an absolute path, make sure the first character is not a slash (“/”);
the underlying Win32 ShellExecute function doesn’t work if it is.

stat(…)
stat(path) -> stat result

Perform a stat system call on the given path.

stat_float_times(…)
stat_float_times([newval]) -> oldval

Determine whether os.[lf]stat represents time stamps as float objects.
If newval is True, future calls to stat() return floats, if it is False,
future calls return ints.
If newval is omitted, return the current setting.

strerror(…)
strerror(code) -> string

Translate an error code to a message string.

system(…)
system(command) -> exit_status

Execute the command (a string) in a subshell.

tempnam(…)
tempnam([dir[, prefix]]) -> string

Return a unique name for a temporary file.
The directory and a prefix may be specified as strings; they may be omitted
or None if not needed.

times(…)
times() -> (utime, stime, cutime, cstime, elapsed_time)

Return a tuple of floating point numbers indicating process times.

tmpfile(…)
tmpfile() -> file object

Create a temporary file with no directory entries.

tmpnam(…)
tmpnam() -> string

Return a unique name for a temporary file.

umask(…)
umask(new_mask) -> old_mask

Set the current numeric umask and return the previous umask.

unlink(…)
unlink(path)

Remove a file (same as remove(path)).

urandom(…)
urandom(n) -> str

Return n random bytes suitable for cryptographic use.

utime(…)
utime(path, (atime, mtime))
utime(path, None)

Set the access and modified time of the file to the given values. If the
second form is used, set the access and modified times to the current time.

waitpid(…)
waitpid(pid, options) -> (pid, status << 8)

Wait for completion of a given process. options is ignored on Windows.

walk(top, topdown=True, onerror=None, followlinks=False)
Directory tree generator.

For each directory in the directory tree rooted at top (including top
itself, but excluding ‘.’ and ‘..’), yields a 3-tuple

dirpath, dirnames, filenames

dirpath is a string, the path to the directory. dirnames is a list of
the names of the subdirectories in dirpath (excluding ‘.’ and ‘..’).
filenames is a list of the names of the non-directory files in dirpath.
Note that the names in the lists are just names, with no path components.
To get a full path (which begins with top) to a file or directory in
dirpath, do os.path.join(dirpath, name).

If optional arg ‘topdown’ is true or not specified, the triple for a
directory is generated before the triples for any of its subdirectories
(directories are generated top down). If topdown is false, the triple
for a directory is generated after the triples for all of its
subdirectories (directories are generated bottom up).

When topdown is true, the caller can modify the dirnames list in-place
(e.g., via del or slice assignment), and walk will only recurse into the
subdirectories whose names remain in dirnames; this can be used to prune
the search, or to impose a specific order of visiting. Modifying
dirnames when topdown is false is ineffective, since the directories in
dirnames have already been generated by the time dirnames itself is
generated.

By default errors from the os.listdir() call are ignored. If
optional arg ‘onerror’ is specified, it should be a function; it
will be called with one argument, an os.error instance. It can
report the error to continue with the walk, or raise the exception
to abort the walk. Note that the filename is available as the
filename attribute of the exception object.

By default, os.walk does not follow symbolic links to subdirectories on
systems that support them. In order to get this functionality, set the
optional argument ‘followlinks’ to true.

Caution: if you pass a relative pathname for top, don’t change the
current working directory between resumptions of walk. walk never
changes the current directory, and assumes that the client doesn’t
either.

Example:

import os
from os.path import join, getsize
for root, dirs, files in os.walk(‘python/Lib/email’):
print root, “consumes”,
print sum([getsize(join(root, name)) for name in files]),
print “bytes in”, len(files), “non-directory files”
if ‘CVS’ in dirs:
dirs.remove(‘CVS’) # don’t visit CVS directories

write(…)
write(fd, string) -> byteswritten

Write a string to a file descriptor.

DATA
F_OK = 0
O_APPEND = 8
O_BINARY = 32768
O_CREAT = 256
O_EXCL = 1024
O_NOINHERIT = 128
O_RANDOM = 16
O_RDONLY = 0
O_RDWR = 2
O_SEQUENTIAL = 32
O_SHORT_LIVED = 4096
O_TEMPORARY = 64
O_TEXT = 16384
O_TRUNC = 512
O_WRONLY = 1
P_DETACH = 4
P_NOWAIT = 1
P_NOWAITO = 3
P_OVERLAY = 2
P_WAIT = 0
R_OK = 4
SEEK_CUR = 1
SEEK_END = 2
SEEK_SET = 0
TMP_MAX = 32767
W_OK = 2
X_OK = 1
__all__ = [‘altsep’, ‘curdir’, ‘pardir’, ‘sep’, ‘extsep’, ‘pathsep’, ‘…
altsep = ‘/’
curdir = ‘.’
defpath = r’.;C:\bin’
devnull = ‘nul’
environ = {‘TMP’: ‘C:\\Users\\bing\\AppData\\Local\\Temp’,…Users\\Pu…
extsep = ‘.’
linesep = ‘\r\n’
name = ‘nt’
pardir = ‘..’
pathsep = ‘;’
sep = r’\’

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Category: OS

About the Author ()

My name is John Link.I am 26 years old. My major is Computer science and technology. I am a junior programmer with Python.

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