pydu/docs/system.md

System

Utils for handling system, like to track file, make directory, link and so on.

system.FileTracker

FileTracker()

Track current opening files, started with FileTracker.track(). When opening several files, FileTracker tracks them and you can locate them by calling FileTraker.get_openfiles().

FiltTracker.track()

Start tracking opening files.

FiltTracker.untrack()

Stop tracking opening files.

FiltTracker.get_openfiles()

Get current opening files.

>>> from pydu.system import FileTracker
>>> FileTracker.track()
>>> f = open('test', 'w')
>>> FileTracker.get_openfiles()
{<_io.TextIOWrapper name='test' mode='w' encoding='UTF-8'>}
>>> f.close()
>>> FileTracker.get_openfiles()
set()
>>> FileTracker.untrack()
>>> f = open('test', 'w')
>>> FileTracker.get_openfiles()
set()

system.makedirs

makedirs(path, mode=0o755, ignore_errors=False, exist_ok=False)

Based on os.makedirs,create a leaf directory and all intermediate ones. mode default is 0o755. When make an exists path, if exist_ok is false, makedirs will raise an Exception. If ignore_errors which will ignore all errors raised by os.makedirs.

>>> from pydu.system import makedirs
>>> makedirs('test1/test2')
>>> makedirs('test1',exist_ok=True)
>>> makedirs('test1')
Traceback (most recent call last):
...    OSError: Create dir: test1 error.

system.remove

remove(path, mode=0o755, ignore_errors=False, onerror)

Remove a file or directory.

If ignore_errors is set, errors are ignored; otherwise, if onerror is set, it is called to handle the error with arguments (func , path , exc_info ) where func is platform and implementation dependent; path is the argument to that function that caused it to fail; and exc_info is a tuple returned by sys.exc_info(). If ignore_errors is False and onerror is None, it attempts to set path as writeable and then proceed with deletion if path is read-only, or raise an exception if path is not read-only.

>>> from pydu.system import makedirs
>>> from pydu.system import remove
>>> from pydu.system import touch
>>> makedirs('test')
>>> remove('test')
>>> touch('test.txt')
>>> remove('test.txt')
>>> remove('test.txt', ignore_errors=True)
>>> remove('test.txt')
Traceback (most recent call last):
...    OSError: Remove path: test error. Reason: [Errno 2] No such file or directory: 'test.txt'

system.removes

removes(paths, mode=0o755, ignore_errors=False, onerror)

Remove a list of file and/or directory.Other parameters same as remove.

>>> from pydu.system import makedirs
>>> from pydu.system import remove
>>> from pydu.system import open_file
>>> makedirs('test1')
>>> makedirs('test2')
>>> open_file('test.txt')
>>> removes(['test.txt','test1','test2'])

system.open_file

open_file(path, mode='wb+', buffer_size=-1, ignore_errors=False):

Open a file, defualt mode wb+. If path not exists, it will be created automatically. If ignore_errors is set, errors are ignored.

>>> from pydu.system import open_file
>>> open_file('test.txt')
>>> ls
test.txt
>>> open_file('test1.txt',mode='r')
Traceback (most recent call last):
...    OSError: Open file: test1.txt error

system.copy

copy(src, dst, ignore_errors=False, follow_symlinks=True):

Copy data and mode bits (cp src dst).Both the source and destination may be a directory.When copy a directory,which contains a symlink,if the optional symlinks flag is true, symbolic links in the source tree result in symbolic links in the destination tree; if it is false, the contents of the files pointed to by symbolic links are copied.When copy a file,if follow_symlinks is false and src is a symbolic link, a new symlink will be created instead of copying the file it points to,else the contents of the file pointed to by symbolic links is copied.

>>> from pydu.system import copy,symlink
>>> from pydu.system import makedirs,open_fle
>>> open_fle('test/test.txt')
>>> symlink('test/test.txt','test/test.link')
>>> copy('test/test.link','test/test_copy1.link')
>>> copy('test/test.link','test/test_copy2.link',follow_symlink=False)

system.touch

touch(path):

Make a new file.

>>> from pydu.system import touch
>>> touch('test.txt')

system.symlink

symlink(src, dst, overwrite=False, ignore_errors=False)

It create a symbolic link pointing to source named link_name.If dist is exist and overwrite is true,a new symlink will be created.

>>> from pydu.system import symlink
>>> symlink('test.txt','test.link')

!> symlink can only be used on unix-like system.

system.link

link(src, dst, overwrite=False, ignore_errors=False):

It create a hard link pointing to source named link_name.If dist is exist and overwrite is true, a new link will be created.

>>> from pydu.system import link
>>> link('test.txt','test.link')

!> link can only be used on unix-like system.

system.which

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.

which is shutil.which in Python 3.

>>> from pydu.system import which
>>> which('echo')
/bin/echo

system.chmod

chmod(path, mode, recursive=False)

Change permissions to the given mode. If recursive is True perform recursively.

>>> from pydu.system import chmod
>>> chmod('/opt/sometest', 0o744)
>>> oct(os.stat('/opt/sometest').st_mode)[-3:]
'744'

!> Although Windows supports chmod, you can only set the file’s read-only flag with it (via the stat.S_IWRITE and stat.S_IREAD constants or a corresponding integer value). All other bits are ignored.

system.chcp

chcp(code)

Context manager which sets the active code page number. It could also be used as function.

>>> from pydu.system import chcp
>>> chcp(437)
<active code page number: 437>
>>> with chcp(437):
...     pass
>>>

!> chcp can only be used on Windows system.

system.preferredencoding

preferredencoding(code)

Get best encoding for the system.