如何在Python中“cd”?
cd
在shell命令中更改工作目录。
如何在Python中更改当前的工作目录?
您可以使用以下方式更改工作目录:
import os os.chdir(path)
使用此方法时有两个最佳做法:
- 在无效path上捕获exception(WindowsError,OSError)。 如果引发exception,请不要执行任何recursion操作,特别是破坏性操作。 他们将在旧的道路上运作,而不是新的道路。
- 完成后,返回到旧的目录。 这可以通过将你的chdir调用包装在上下文pipe理器中以exception安全的方式完成,就像Brian M. Hunt在他的回答中所做的那样。
更改子stream程中的当前工作目录不会更改父进程中的当前工作目录。 Python解释器也是如此。 您不能使用os.chdir()
更改调用进程的CWD。
这里是一个上下文pipe理器来更改工作目录的例子。 这比其他地方提到的ActiveState版本更简单,但是这样可以完成工作。
上下文pipe理器: cd
import os class cd: """Context manager for changing the current working directory""" def __init__(self, newPath): self.newPath = os.path.expanduser(newPath) def __enter__(self): self.savedPath = os.getcwd() os.chdir(self.newPath) def __exit__(self, etype, value, traceback): os.chdir(self.savedPath)
或者使用ContextManager尝试更简洁的等效(下面) 。
例
import subprocess # just to call an arbitrary command eg 'ls' # enter the directory like this: with cd("~/Library"): # we are in ~/Library subprocess.call("ls") # outside the context manager we are back wherever we started.
我会使用os.chdir
像这样:
os.chdir("/path/to/change/to")
顺便说一句,如果你需要找出你当前的path,使用os.getcwd()
。
更多在这里
cd()
很容易使用生成器和装饰器来写入。
from contextlib import contextmanager import os @contextmanager def cd(newdir): prevdir = os.getcwd() os.chdir(os.path.expanduser(newdir)) try: yield finally: os.chdir(prevdir)
然后,即使引发exception,目录也会被还原:
os.chdir('/home') with cd('/tmp'): # ... raise Exception("There's no place like home.") # Directory is now back to '/home'.
如果您使用的是相对较新版本的Python,则还可以使用上下文pipe理器,例如:
from __future__ import with_statement from grizzled.os import working_directory with working_directory(path_to_directory): # code in here occurs within the directory # code here is in the original directory
UPDATE
如果你喜欢推出自己的:
import os from contextlib import contextmanager @contextmanager def working_directory(directory): owd = os.getcwd() try: os.chdir(directory) yield directory finally: os.chdir(owd)
os.chdir()
是正确的方法。
正如其他人已经指出的,以上所有的解决scheme只是改变了当前进程的工作目录。 当你退回到Unix shell时,这会丢失。 如果不顾一切,你可以用这个可怕的黑客来更改Unix上的父shell目录:
def quote_against_shell_expansion(s): import pipes return pipes.quote(s) def put_text_back_into_terminal_input_buffer(text): # use of this means that it only works in an interactive session # (and if the user types while it runs they could insert characters between the characters in 'text'!) import fcntl, termios for c in text: fcntl.ioctl(1, termios.TIOCSTI, c) def change_parent_process_directory(dest): # the horror put_text_back_into_terminal_input_buffer("cd "+quote_against_shell_expansion(dest)+"\n")
os.chdir()
是cd
的Pythonic版本。
根据Brian指出的方向,基于sh (1.0.8+)
from sh import cd, ls cd('/tmp') print ls()
如果您想执行“cd ..”选项,只需键入:
os.chdir( “..”)
它与Windows cmd中的相同:cd ..当然, import os是必需的(例如,input它作为代码的第一行)
在python命令行上试试这个:
import os print os.getcwd()
改变脚本进程的当前目录是微不足道的。 我想这个问题实际上是如何改变从中调用python脚本的命令窗口的当前目录,这是非常困难的。 Windows中的Bat脚本或Bash shell中的Bash脚本可以使用普通的cd命令执行此操作,因为shell本身就是解释器。 在Windows和Linux中,Python都是一个程序,没有一个程序可以直接改变父母的环境。 然而,一个简单的shell脚本和一个Python脚本的组合可以达到预期的效果。 例如,为了制作一个扩展的带有遍历历史的cd命令,用于向后/向前/select重访,我写了一个由一个简单的bat脚本调用的相对复杂的Python脚本。 遍历列表存储在一个文件中,目标目录在第一行。 当python脚本返回时,bat脚本读取文件的第一行,并将其作为cd的参数。 完整的蝙蝠脚本(减去评论为简洁)是:
if _%1 == _. goto cdDone if _%1 == _? goto help if /i _%1 NEQ _-H goto doCd :help echo d.bat and dSup.py 2016.03.05. Extended chdir. echo -C = clear traversal list. echo -B or nothing = backward (to previous dir). echo -F or - = forward (to next dir). echo -R = remove current from list and return to previous. echo -S = select from list. echo -H, -h, ? = help. echo . = make window title current directory. echo Anything else = target directory. goto done :doCd %~dp0dSup.py %1 for /F %%d in ( %~dp0dSupList ) do ( cd %%d if errorlevel 1 ( %~dp0dSup.py -R ) goto cdDone ) :cdDone title %CD% :done
python脚本dSup.py是:
import sys, os, msvcrt def indexNoCase ( slist, s ) : for idx in range( len( slist )) : if slist[idx].upper() == s.upper() : return idx raise ValueError # .........main process ................... if len( sys.argv ) < 2 : cmd = 1 # No argument defaults to -B, the most common operation elif sys.argv[1][0] == '-': if len(sys.argv[1]) == 1 : cmd = 2 # '-' alone defaults to -F, second most common operation. else : cmd = 'CBFRS'.find( sys.argv[1][1:2].upper()) else : cmd = -1 dir = os.path.abspath( sys.argv[1] ) + '\n' # cmd is -1 = path, 0 = C, 1 = B, 2 = F, 3 = R, 4 = S fo = open( os.path.dirname( sys.argv[0] ) + '\\dSupList', mode = 'a+t' ) fo.seek( 0 ) dlist = fo.readlines( -1 ) if len( dlist ) == 0 : dlist.append( os.getcwd() + '\n' ) # Prime new directory list with current. if cmd == 1 : # B: move backward, ie to previous target = dlist.pop(0) dlist.append( target ) elif cmd == 2 : # F: move forward, ie to next target = dlist.pop( len( dlist ) - 1 ) dlist.insert( 0, target ) elif cmd == 3 : # R: remove current from list. This forces cd to previous, a # desireable side-effect dlist.pop( 0 ) elif cmd == 4 : # S: select from list # The current directory (dlist[0]) is included essentially as ESC. for idx in range( len( dlist )) : print( '(' + str( idx ) + ')', dlist[ idx ][:-1]) while True : inp = msvcrt.getche() if inp.isdigit() : inp = int( inp ) if inp < len( dlist ) : print( '' ) # Print the newline we didn't get from getche. break print( ' is out of range' ) # Select 0 means the current directory and the list is not changed. Otherwise # the selected directory is moved to the top of the list. This can be done by # either rotating the whole list until the selection is at the head or pop it # and insert it to 0. It isn't obvious which would be better for the user but # since pop-insert is simpler, it is used. if inp > 0 : dlist.insert( 0, dlist.pop( inp )) elif cmd == -1 : # -1: dir is the requested new directory. # If it is already in the list then remove it before inserting it at the head. # This takes care of both the common case of it having been recently visited # and the less common case of user mistakenly requesting current, in which # case it is already at the head. Deleting and putting it back is a trivial # inefficiency. try: dlist.pop( indexNoCase( dlist, dir )) except ValueError : pass dlist = dlist[:9] # Control list length by removing older dirs (should be # no more than one). dlist.insert( 0, dir ) fo.truncate( 0 ) if cmd != 0 : # C: clear the list fo.writelines( dlist ) fo.close() exit(0)
为了便于交互使用, ipython拥有所有内置的常用shell命令。