cd as in the shell command to change the working directory.
How do I change the current working directory in Python?
You can change the working directory with:
import os os.chdir(path)
There are two best practices to follow when using this method:
- Catch the exception (WindowsError, OSError) on invalid path. If the exception is thrown, do not perform any recursive operations, especially destructive ones. They will operate on the old path and not the new one.
- Return to your old directory when you’re done. This can be done in an exception-safe manner by wrapping your chdir call in a context manager, like Brian M. Hunt did in his answer.
Changing the current working directory in a subprocess does not change the current working directory in the parent process. This is true of the Python interpreter as well. You cannot use
os.chdir() to change the CWD of the calling process.
Here’s an example of a context manager to change the working directory. It is simpler than an ActiveState version referred to elsewhere, but this gets the job done.
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)
import subprocess # just to call an arbitrary command e.g. '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.
I would use
os.chdir like this:
By the way, if you need to figure out your current path, use
cd() is easy to write using a generator and a decorator.
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)
Then, the directory is reverted even after an exception is thrown:
os.chdir('/home') with cd('/tmp'): # ... raise Exception("There's no place like home.") # Directory is now back to '/home'.
If you’re using a relatively new version of Python, you can also use a context manager, such as this one:
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
If you prefer to roll your own:
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() is the right way.
As already pointed out by others, all the solutions above only change the working directory of the current process. This is lost when you exit back to the Unix shell. If desperate you can change the parent shell directory on Unix with this horrible hack:
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() is the Pythonic version of
Further into direction pointed out by Brian and based on sh (1.0.8+)
from sh import cd, ls cd('/tmp') print ls()
If You would like to perform something like “cd..” option, just type:
it is the same as in Windows cmd: cd..
Of course import os is neccessary (e.g type it as 1st line of your code)
Try this on python command line:
import os print os.getcwd()
Changing the current directory of the script process is trivial. I think the question is actually how to change the current directory of the command window from which a python script is invoked, which is very difficult. A Bat script in Windows or a Bash script in a Bash shell can do this with an ordinary cd command because the shell itself is the interpreter. In both Windows and Linux Python is a program and no program can directly change its parent’s environment. However the combination of a simple shell script with a Python script doing most of the hard stuff can achieve the desired result. For example, to make an extended cd command with traversal history for backward/forward/select revisit, I wrote a relatively complex Python script invoked by a simple bat script. The traversal list is stored in a file, with the target directory on the first line. When the python script returns, the bat script reads the first line of the file and makes it the argument to cd. The complete bat script (minus comments for brevity) is:
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
The python script, dSup.py is:
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 == '-': if len(sys.argv) == 1 : cmd = 2 # '-' alone defaults to -F, second most common operation. else : cmd = 'CBFRS'.find( sys.argv[1:2].upper()) else : cmd = -1 dir = os.path.abspath( sys.argv ) + '\n' # cmd is -1 = path, 0 = C, 1 = B, 2 = F, 3 = R, 4 = S fo = open( os.path.dirname( sys.argv ) + '\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, i.e. to previous target = dlist.pop(0) dlist.append( target ) elif cmd == 2 : # F: move forward, i.e. 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) 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)
and for easy interactive use, ipython has all the common shell commands built in.