How can I safely create a nested directory

Question

What is the most elegant way to check if the directory a file is going to be written to exists  and if not  create the directory using Python  Here is what I tried   import os  file path     my directory filename txt  directory   os path dirname file path   try      os stat directory  except      os mkdir directory          f   file filename    Somehow  I missed os path exists  thanks kanja  Blair  and Douglas   This is what I have now   def ensure dir file path       directory   os path dirname file path      if not os path exists directory           os makedirs directory    Is there a flag for  open   that makes this happen automatically

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I use os path exists    here is a Python 3 script that can be used to check if a directory exists  create one if it does not exist  and delete it if it does exist  if desired    It prompts users for input of the directory and can be easily modified

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Try the os path exists function  if not os path exists dir       os mkdir dir

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You can both create a file  and all its parent directories in 1 command with fastcore extension to pathlib  path mk write data  from fastcore utils import Path Path   dir to file txt   mk write  Hello World

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Try the os path exists function  if not os path exists dir       os mkdir dir

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I found this Q A and I was initially puzzled by some of the failures and errors I was getting  I am working in Python 3  v 3 5 in an Anaconda virtual environment on an Arch Linux x86 64 system    Consider this directory structure    -- output             dir     -- corpus          file     -- corpus2         dir     -- subdir          dir   Here are my experiments notes  which clarifies things     ----------------------------------------------------------------------------    1  https   stackoverflow com questions 273192 how-can-i-create-a-directory-if-it-does-not-exist  import pathlib      Notes          1   Include a trailing slash at the end of the directory path               Method 1   below           2   If a subdirectory in your intended path matches an existing file             with same name  you will get the following error               NotADirectoryError   Errno 20  Not a directory             Uncomment and try each of these  out dir  paths  singly     ----------------------------------------------------------------------------   METHOD 1    Re-running does not overwrite existing directories and files  no errors     out dir    output corpus3                    no error but no dir created  missing tailing      out dir    output corpus3                    works   out dir    output corpus3 doc1               no error but no dir created  missing tailing      out dir    output corpus3 doc1               works   out dir    output corpus3 doc1 doc txt       no error but no file created  os makedirs creates dir  not files    -    out dir    output corpus2 tfidf              fails with  Errno 20   existing file named  corpus2     out dir    output corpus3 tfidf              works   out dir    output corpus3 a b c d            works     2  https   docs python org 3 library os html os makedirs    Uncomment these to run  Method 1     directory   os path dirname out dir   os makedirs directory  mode 0o777  exist ok True     ----------------------------------------------------------------------------   METHOD 2    Re-running does not overwrite existing directories and files  no errors     out dir    output corpus3                    works   out dir    output corpus3                    works   out dir    output corpus3 doc1               works   out dir    output corpus3 doc1               works   out dir    output corpus3 doc1 doc txt       no error but creates a     doc txt   dir   out dir    output corpus2 tfidf              fails with  Errno 20   existing file named  corpus2     out dir    output corpus3 tfidf              works   out dir    output corpus3 a b c d            works    Uncomment these to run  Method 2     import os  errno  try          os makedirs out dir   except OSError as e          if e errno    errno EEXIST                  raise   ----------------------------------------------------------------------------   Conclusion  in my opinion   Method 2  is more robust    1  How can I create a directory if it does not exist    2  https   docs python org 3 library os html os makedirs

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import os if os path isfile filename       print  file exists  else       Your code here       Where your code here is use the  touch  command   This will check if the file is there if it is not then it will create it

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Under Linux you can create directory in one line  import os os system  quot mkdir -p  0  quot  format  mydir

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Use this command check and create dir   if not os path isdir test img dir        os mkdir test img dir

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Insights on the specifics of this situation  You give a particular file at a certain path and you pull the directory from the file path  Then after making sure you have the directory  you attempt to open a file for reading  To comment on this code    filename     my directory filename txt  dir   os path dirname filename     We want to avoid overwriting the builtin function  dir  Also  filepath or perhaps fullfilepath is probably a better semantic name than filename so this would be better written   import os filepath     my directory filename txt  directory   os path dirname filepath    Your end goal is to open this file  you initially state  for writing  but you re essentially approaching this goal  based on your code  like this  which opens the file for reading    if not os path exists directory       os makedirs directory  f   file filename     Assuming opening for reading  Why would you make a directory for a file that you expect to be there and be able to read    Just attempt to open the file   with open filepath  as my file      do stuff my file    If the directory or file isn t there  you ll get an IOError with an associated error number  errno ENOENT will point to the correct error number regardless of your platform  You can catch it if you want  for example   import errno try      with open filepath  as my file          do stuff my file  except IOError as error      if error errno    errno ENOENT          print  ignoring error because directory or file is not there      else          raise   Assuming we re opening for writing  This is probably what you re wanting   In this case  we probably aren t facing any race conditions  So just do as you were  but note that for writing  you need to open with the w mode  or a to append   It s also a Python best practice to use the context manager for opening files   import os if not os path exists directory       os makedirs directory  with open filepath   w   as my file      do stuff my file    However  say we have several Python processes that attempt to put all their data into the same directory  Then we may have contention over creation of the directory  In that case it s best to wrap the makedirs call in a try-except block   import os import errno if not os path exists directory       try          os makedirs directory      except OSError as error          if error errno    errno EEXIST              raise with open filepath   w   as my file      do stuff my file

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Check if a directory exists and create it if necessary    The direct answer to this is  assuming a simple situation where you don t expect other users or processes to be messing with your directory   if not os path exists d       os makedirs d    or if making the directory is subject to race conditions  i e  if after checking the path exists  something else may have already made it  do this   import errno try      os makedirs d  except OSError as exception      if exception errno    errno EEXIST          raise   But perhaps an even better approach is to sidestep the resource contention issue  by using temporary directories via tempfile   import tempfile  d   tempfile mkdtemp     Here s the essentials from the online doc    mkdtemp suffix     prefix  tmp   dir None      User-callable function to create and return a unique temporary     directory   The return value is the pathname of the directory       The directory is readable  writable  and searchable only by the     creating user       Caller is responsible for deleting the directory when done with it     New in Python 3 5  pathlib Path with exist ok  There s a new Path object  as of 3 4  with lots of methods one would want to use with paths - one of which is mkdir    For context  I m tracking my weekly rep with a script  Here s the relevant parts of code from the script that allow me to avoid hitting Stack Overflow more than once a day for the same data    First the relevant imports   from pathlib import Path import tempfile   We don t have to deal with os path join now - just join path parts with a     directory   Path tempfile gettempdir       sodata    Then I idempotently ensure the directory exists - the exist ok argument shows up in Python 3 5   directory mkdir exist ok True    Here s the relevant part of the documentation      If exist ok is true  FileExistsError exceptions will be ignored  same behavior as the POSIX mkdir -p command   but only if the last path component is not an existing non-directory file    Here s a little more of the script - in my case  I m not subject to a race condition  I only have one process that expects the directory  or contained files  to be there  and I don t have anything trying to remove the directory    todays file   directory   str datetime datetime utcnow   date    if todays file exists        logger info  todays file exists      str todays file       df   pd read json str todays file     Path objects have to be coerced to str before other APIs that expect str paths can use them   Perhaps Pandas should be updated to accept instances of the abstract base class  os PathLike

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You have to set the full path before creating the directory   import os sys inspect import pathlib  currentdir   os path dirname os path abspath inspect getfile inspect currentframe      your folder   currentdir          your folder   if not os path exists your folder      pathlib Path your folder  mkdir parents True  exist ok True    This works for me and hopefully  it will works for you as well

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If you consider the following    os path isdir   tmp dirname     means a directory  path  exists AND is a directory  So for me this way does what I need  So I can make sure it is folder  not a file  and exists

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Starting from Python 3 5  pathlib Path mkdir has an exist ok flag  from pathlib import Path path   Path   my directory filename txt   path parent mkdir parents True  exist ok True     path parent   os path dirname path   This recursively creates the directory and does not raise an exception if the directory already exists   just as os makedirs got an exist ok flag starting from python 3 2 e g os makedirs path  exist ok True    Note  when i posted this answer none of the other answers mentioned exist ok

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On Python   3 5  use pathlib Path mkdir   from pathlib import Path Path   my directory   mkdir parents True  exist ok True    For older versions of Python  I see two answers with good qualities  each with a small flaw  so I will give my take on it   Try os path exists  and consider os makedirs for the creation   import os if not os path exists directory       os makedirs directory    As noted in comments and elsewhere  there s a race condition  ndash  if the directory is created between the os path exists and the os makedirs calls  the os makedirs will fail with an OSError  Unfortunately  blanket-catching OSError and continuing is not foolproof  as it will ignore a failure to create the directory due to other factors  such as insufficient permissions  full disk  etc   One option would be to trap the OSError and examine the embedded error code  see Is there a cross-platform way of getting information from Python   s OSError    import os  errno  try      os makedirs directory  except OSError as e      if e errno    errno EEXIST          raise   Alternatively  there could be a second os path exists  but suppose another created the directory after the first check  then removed it before the second one  ndash  we could still be fooled    Depending on the application  the danger of concurrent operations may be more or less than the danger posed by other factors such as file permissions  The developer would have to know more about the particular application being developed and its expected environment before choosing an implementation   Modern versions of Python improve this code quite a bit  both by exposing FileExistsError  in 3 3       try      os makedirs  path to directory   except FileExistsError        directory already exists     pass      and by allowing a keyword argument to os makedirs called exist ok  in 3 2     os makedirs  path to directory   exist ok True     succeeds even if directory exists

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Call the function create dir   at the entry point of your program project   import os  def create dir directory       if not os path exists directory           print  Creating Directory   directory          os makedirs directory   create dir  Project directory

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I have put the following down  It s not totally foolproof though   import os  dirname    create me   try      os makedirs dirname  except OSError      if os path exists dirname             We are nearly safe         pass     else            There was an error on creation  so make sure we know about it         raise   Now as I say  this is not really foolproof  because we have the possiblity of failing to create the directory  and another process creating it during that period

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For a one-liner solution  you can use IPython utils path ensure dir exists     from IPython utils path import ensure dir exists ensure dir exists dir    From the documentation  Ensure that a directory exists  If it doesn   t exist  try to create it and protect against a race condition if another process is doing the same

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On Python   3 5  use pathlib Path mkdir   from pathlib import Path Path   my directory   mkdir parents True  exist ok True    For older versions of Python  I see two answers with good qualities  each with a small flaw  so I will give my take on it   Try os path exists  and consider os makedirs for the creation   import os if not os path exists directory       os makedirs directory    As noted in comments and elsewhere  there s a race condition  ndash  if the directory is created between the os path exists and the os makedirs calls  the os makedirs will fail with an OSError  Unfortunately  blanket-catching OSError and continuing is not foolproof  as it will ignore a failure to create the directory due to other factors  such as insufficient permissions  full disk  etc   One option would be to trap the OSError and examine the embedded error code  see Is there a cross-platform way of getting information from Python   s OSError    import os  errno  try      os makedirs directory  except OSError as e      if e errno    errno EEXIST          raise   Alternatively  there could be a second os path exists  but suppose another created the directory after the first check  then removed it before the second one  ndash  we could still be fooled    Depending on the application  the danger of concurrent operations may be more or less than the danger posed by other factors such as file permissions  The developer would have to know more about the particular application being developed and its expected environment before choosing an implementation   Modern versions of Python improve this code quite a bit  both by exposing FileExistsError  in 3 3       try      os makedirs  path to directory   except FileExistsError        directory already exists     pass      and by allowing a keyword argument to os makedirs called exist ok  in 3 2     os makedirs  path to directory   exist ok True     succeeds even if directory exists

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You can use os listdir for this   import os if  dirName  in os listdir  parentFolderPath       print  Directory Exists

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I found this Q A and I was initially puzzled by some of the failures and errors I was getting  I am working in Python 3  v 3 5 in an Anaconda virtual environment on an Arch Linux x86 64 system    Consider this directory structure    -- output             dir     -- corpus          file     -- corpus2         dir     -- subdir          dir   Here are my experiments notes  which clarifies things     ----------------------------------------------------------------------------    1  https   stackoverflow com questions 273192 how-can-i-create-a-directory-if-it-does-not-exist  import pathlib      Notes          1   Include a trailing slash at the end of the directory path               Method 1   below           2   If a subdirectory in your intended path matches an existing file             with same name  you will get the following error               NotADirectoryError   Errno 20  Not a directory             Uncomment and try each of these  out dir  paths  singly     ----------------------------------------------------------------------------   METHOD 1    Re-running does not overwrite existing directories and files  no errors     out dir    output corpus3                    no error but no dir created  missing tailing      out dir    output corpus3                    works   out dir    output corpus3 doc1               no error but no dir created  missing tailing      out dir    output corpus3 doc1               works   out dir    output corpus3 doc1 doc txt       no error but no file created  os makedirs creates dir  not files    -    out dir    output corpus2 tfidf              fails with  Errno 20   existing file named  corpus2     out dir    output corpus3 tfidf              works   out dir    output corpus3 a b c d            works     2  https   docs python org 3 library os html os makedirs    Uncomment these to run  Method 1     directory   os path dirname out dir   os makedirs directory  mode 0o777  exist ok True     ----------------------------------------------------------------------------   METHOD 2    Re-running does not overwrite existing directories and files  no errors     out dir    output corpus3                    works   out dir    output corpus3                    works   out dir    output corpus3 doc1               works   out dir    output corpus3 doc1               works   out dir    output corpus3 doc1 doc txt       no error but creates a     doc txt   dir   out dir    output corpus2 tfidf              fails with  Errno 20   existing file named  corpus2     out dir    output corpus3 tfidf              works   out dir    output corpus3 a b c d            works    Uncomment these to run  Method 2     import os  errno  try          os makedirs out dir   except OSError as e          if e errno    errno EEXIST                  raise   ----------------------------------------------------------------------------   Conclusion  in my opinion   Method 2  is more robust    1  How can I create a directory if it does not exist    2  https   docs python org 3 library os html os makedirs

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I would personally recommend that you use os path isdir   to test instead of os path exists      gt  gt  gt  os path exists   tmp dirname   True  gt  gt  gt  os path exists   tmp dirname filename etc   True  gt  gt  gt  os path isdir   tmp dirname filename etc   False  gt  gt  gt  os path isdir   tmp fakedirname   False   If you have    gt  gt  gt  dir   raw input          And a foolish user input       tmp dirname filename etc       You re going to end up with a directory named filename etc when you pass that argument to os makedirs   if you test with os path exists

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Python 3 5    import pathlib pathlib Path   my directory   mkdir parents True  exist ok True     pathlib Path mkdir as used above recursively creates the directory and does not raise an exception if the directory already exists  If you don t need or want the parents to be created  skip the parents argument   Python 3 2    Using pathlib   If you can  install the current pathlib backport named pathlib2  Do not install the older unmaintained backport named pathlib  Next  refer to the Python 3 5  section above and use it the same   If using Python 3 4  even though it comes with pathlib  it is missing the useful exist ok option  The backport is intended to offer a newer and superior implementation of mkdir which includes this missing option   Using os   import os os makedirs path  exist ok True    os makedirs as used above recursively creates the directory and does not raise an exception if the directory already exists  It has the optional exist ok argument only if using Python 3 2   with a default value of False  This argument does not exist in Python 2 x up to 2 7  As such  there is no need for manual exception handling as with Python 2 7   Python 2 7    Using pathlib   If you can  install the current pathlib backport named pathlib2  Do not install the older unmaintained backport named pathlib  Next  refer to the Python 3 5  section above and use it the same   Using os   import os try       os makedirs path  except OSError      if not os path isdir path           raise   While a naive solution may first use os path isdir followed by os makedirs  the solution above reverses the order of the two operations  In doing so  it prevents a common race condition having to do with a duplicated attempt at creating the directory  and also disambiguates files from directories   Note that capturing the exception and using errno is of limited usefulness because OSError   Errno 17  File exists  i e  errno EEXIST  is raised for both files and directories  It is more reliable simply to check if the directory exists   Alternative   mkpath creates the nested directory  and does nothing if the directory already exists  This works in both Python 2 and 3   import distutils dir util distutils dir util mkpath path    Per Bug 10948  a severe limitation of this alternative is that it works only once per python process for a given path  In other words  if you use it to create a directory  then delete the directory from inside or outside Python  then use mkpath again to recreate the same directory  mkpath will simply silently use its invalid cached info of having previously created the directory  and will not actually make the directory again  In contrast  os makedirs doesn t rely on any such cache  This limitation may be okay for some applications     With regard to the directory s mode  please refer to the documentation if you care about it

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Using try except and the right error code from errno module gets rid of the race condition and is cross-platform   import os import errno  def make sure path exists path       try          os makedirs path      except OSError as exception          if exception errno    errno EEXIST              raise   In other words  we try to create the directories  but if they already exist we ignore the error  On the other hand  any other error gets reported  For example  if you create dir  a  beforehand and remove all permissions from it  you will get an OSError raised with errno EACCES  Permission denied  error 13

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The relevant Python documentation suggests the use of the EAFP coding style  Easier to Ask for Forgiveness than Permission   This means that the code  try      os makedirs path  except OSError as exception      if exception errno    errno EEXIST          raise     else          print   nBE CAREFUL  Directory  s already exists     path   is better than the alternative  if not os path exists path       os makedirs path  else      print   nBE CAREFUL  Directory  s already exists     path   The documentation suggests this exactly because of the race condition discussed in this question  In addition  as others mention here  there is a performance advantage in querying once instead of twice the OS  Finally  the argument placed forward  potentially  in favour of the second code in some cases --when the developer knows the environment the application is running-- can only be advocated in the special case that the program has set up a private environment for itself  and other instances of the same program    Even in that case  this is a bad practice and can lead to long useless debugging  For example  the fact we set the permissions for a directory should not leave us with the impression permissions are set appropriately for our purposes  A parent directory could be mounted with other permissions  In general  a program should always work correctly and the programmer should not expect one specific environment

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You can use mkpath    Create a directory and any missing ancestor directories     If the directory already exists  do nothing   from distutils dir util import mkpath mkpath  test         Note that it will create the ancestor directories as well    It works for Python 2 and 3

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I saw Heikki Toivonen and A-B-B s answers and thought of this variation   import os import errno  def make sure path exists path       try          os makedirs path      except OSError as exception          if exception errno    errno EEXIST or not os path isdir path               raise

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You can use mkpath    Create a directory and any missing ancestor directories     If the directory already exists  do nothing   from distutils dir util import mkpath mkpath  test         Note that it will create the ancestor directories as well    It works for Python 2 and 3

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For a one-liner solution  you can use IPython utils path ensure dir exists     from IPython utils path import ensure dir exists ensure dir exists dir    From the documentation  Ensure that a directory exists  If it doesn   t exist  try to create it and protect against a race condition if another process is doing the same

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Why not use subprocess module if running on a machine that supports command  mkdir with -p option    Works on python 2 7 and python 3 6  from subprocess import call call   mkdir    -p    path1 path2 path3      Should do the trick on most systems   In situations where portability doesn t matter  ex  using docker  the solution is a clean 2 lines  You also don t have to add logic to check if directories exist or not  Finally  it is safe to re-run without any side effects  If you need error handling   from subprocess import check call try      check call   mkdir    -p    path1 path2 path3    except      handle

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Use this command check and create dir   if not os path isdir test img dir        os mkdir test img dir

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In Python 3 4 you can also use the brand new pathlib module   from pathlib import Path path   Path   my directory filename txt   try      if not path parent exists            path parent mkdir parents True  except OSError        handle error  you can also catch specific errors like       FileExistsError and so on

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You have to set the full path before creating the directory   import os sys inspect import pathlib  currentdir   os path dirname os path abspath inspect getfile inspect currentframe      your folder   currentdir          your folder   if not os path exists your folder      pathlib Path your folder  mkdir parents True  exist ok True    This works for me and hopefully  it will works for you as well

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Try the os path exists function  if not os path exists dir       os mkdir dir

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You can both create a file  and all its parent directories in 1 command with fastcore extension to pathlib  path mk write data  from fastcore utils import Path Path   dir to file txt   mk write  Hello World

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I saw Heikki Toivonen and A-B-B s answers and thought of this variation   import os import errno  def make sure path exists path       try          os makedirs path      except OSError as exception          if exception errno    errno EEXIST or not os path isdir path               raise

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Python 3 5    import pathlib pathlib Path   my directory   mkdir parents True  exist ok True     pathlib Path mkdir as used above recursively creates the directory and does not raise an exception if the directory already exists  If you don t need or want the parents to be created  skip the parents argument   Python 3 2    Using pathlib   If you can  install the current pathlib backport named pathlib2  Do not install the older unmaintained backport named pathlib  Next  refer to the Python 3 5  section above and use it the same   If using Python 3 4  even though it comes with pathlib  it is missing the useful exist ok option  The backport is intended to offer a newer and superior implementation of mkdir which includes this missing option   Using os   import os os makedirs path  exist ok True    os makedirs as used above recursively creates the directory and does not raise an exception if the directory already exists  It has the optional exist ok argument only if using Python 3 2   with a default value of False  This argument does not exist in Python 2 x up to 2 7  As such  there is no need for manual exception handling as with Python 2 7   Python 2 7    Using pathlib   If you can  install the current pathlib backport named pathlib2  Do not install the older unmaintained backport named pathlib  Next  refer to the Python 3 5  section above and use it the same   Using os   import os try       os makedirs path  except OSError      if not os path isdir path           raise   While a naive solution may first use os path isdir followed by os makedirs  the solution above reverses the order of the two operations  In doing so  it prevents a common race condition having to do with a duplicated attempt at creating the directory  and also disambiguates files from directories   Note that capturing the exception and using errno is of limited usefulness because OSError   Errno 17  File exists  i e  errno EEXIST  is raised for both files and directories  It is more reliable simply to check if the directory exists   Alternative   mkpath creates the nested directory  and does nothing if the directory already exists  This works in both Python 2 and 3   import distutils dir util distutils dir util mkpath path    Per Bug 10948  a severe limitation of this alternative is that it works only once per python process for a given path  In other words  if you use it to create a directory  then delete the directory from inside or outside Python  then use mkpath again to recreate the same directory  mkpath will simply silently use its invalid cached info of having previously created the directory  and will not actually make the directory again  In contrast  os makedirs doesn t rely on any such cache  This limitation may be okay for some applications     With regard to the directory s mode  please refer to the documentation if you care about it

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I would personally recommend that you use os path isdir   to test instead of os path exists      gt  gt  gt  os path exists   tmp dirname   True  gt  gt  gt  os path exists   tmp dirname filename etc   True  gt  gt  gt  os path isdir   tmp dirname filename etc   False  gt  gt  gt  os path isdir   tmp fakedirname   False   If you have    gt  gt  gt  dir   raw input          And a foolish user input       tmp dirname filename etc       You re going to end up with a directory named filename etc when you pass that argument to os makedirs   if you test with os path exists

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Check if a directory exists and create it if necessary    The direct answer to this is  assuming a simple situation where you don t expect other users or processes to be messing with your directory   if not os path exists d       os makedirs d    or if making the directory is subject to race conditions  i e  if after checking the path exists  something else may have already made it  do this   import errno try      os makedirs d  except OSError as exception      if exception errno    errno EEXIST          raise   But perhaps an even better approach is to sidestep the resource contention issue  by using temporary directories via tempfile   import tempfile  d   tempfile mkdtemp     Here s the essentials from the online doc    mkdtemp suffix     prefix  tmp   dir None      User-callable function to create and return a unique temporary     directory   The return value is the pathname of the directory       The directory is readable  writable  and searchable only by the     creating user       Caller is responsible for deleting the directory when done with it     New in Python 3 5  pathlib Path with exist ok  There s a new Path object  as of 3 4  with lots of methods one would want to use with paths - one of which is mkdir    For context  I m tracking my weekly rep with a script  Here s the relevant parts of code from the script that allow me to avoid hitting Stack Overflow more than once a day for the same data    First the relevant imports   from pathlib import Path import tempfile   We don t have to deal with os path join now - just join path parts with a     directory   Path tempfile gettempdir       sodata    Then I idempotently ensure the directory exists - the exist ok argument shows up in Python 3 5   directory mkdir exist ok True    Here s the relevant part of the documentation      If exist ok is true  FileExistsError exceptions will be ignored  same behavior as the POSIX mkdir -p command   but only if the last path component is not an existing non-directory file    Here s a little more of the script - in my case  I m not subject to a race condition  I only have one process that expects the directory  or contained files  to be there  and I don t have anything trying to remove the directory    todays file   directory   str datetime datetime utcnow   date    if todays file exists        logger info  todays file exists      str todays file       df   pd read json str todays file     Path objects have to be coerced to str before other APIs that expect str paths can use them   Perhaps Pandas should be updated to accept instances of the abstract base class  os PathLike

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On Python   3 5  use pathlib Path mkdir   from pathlib import Path Path   my directory   mkdir parents True  exist ok True    For older versions of Python  I see two answers with good qualities  each with a small flaw  so I will give my take on it   Try os path exists  and consider os makedirs for the creation   import os if not os path exists directory       os makedirs directory    As noted in comments and elsewhere  there s a race condition  ndash  if the directory is created between the os path exists and the os makedirs calls  the os makedirs will fail with an OSError  Unfortunately  blanket-catching OSError and continuing is not foolproof  as it will ignore a failure to create the directory due to other factors  such as insufficient permissions  full disk  etc   One option would be to trap the OSError and examine the embedded error code  see Is there a cross-platform way of getting information from Python   s OSError    import os  errno  try      os makedirs directory  except OSError as e      if e errno    errno EEXIST          raise   Alternatively  there could be a second os path exists  but suppose another created the directory after the first check  then removed it before the second one  ndash  we could still be fooled    Depending on the application  the danger of concurrent operations may be more or less than the danger posed by other factors such as file permissions  The developer would have to know more about the particular application being developed and its expected environment before choosing an implementation   Modern versions of Python improve this code quite a bit  both by exposing FileExistsError  in 3 3       try      os makedirs  path to directory   except FileExistsError        directory already exists     pass      and by allowing a keyword argument to os makedirs called exist ok  in 3 2     os makedirs  path to directory   exist ok True     succeeds even if directory exists

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Try the os path exists function  if not os path exists dir       os mkdir dir

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Check os makedirs    It makes sure the complete path exists    To handle the fact the directory might exist  catch OSError   If exist ok is False  the default   an OSError is raised if the target directory already exists    import os try      os makedirs    path to somewhere   except OSError      pass

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Call the function create dir   at the entry point of your program project   import os  def create dir directory       if not os path exists directory           print  Creating Directory   directory          os makedirs directory   create dir  Project directory

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In Python 3 4 you can also use the brand new pathlib module   from pathlib import Path path   Path   my directory filename txt   try      if not path parent exists            path parent mkdir parents True  except OSError        handle error  you can also catch specific errors like       FileExistsError and so on

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Why not use subprocess module if running on a machine that supports command  mkdir with -p option    Works on python 2 7 and python 3 6  from subprocess import call call   mkdir    -p    path1 path2 path3      Should do the trick on most systems   In situations where portability doesn t matter  ex  using docker  the solution is a clean 2 lines  You also don t have to add logic to check if directories exist or not  Finally  it is safe to re-run without any side effects  If you need error handling   from subprocess import check call try      check call   mkdir    -p    path1 path2 path3    except      handle

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Starting from Python 3 5  pathlib Path mkdir has an exist ok flag  from pathlib import Path path   Path   my directory filename txt   path parent mkdir parents True  exist ok True     path parent   os path dirname path   This recursively creates the directory and does not raise an exception if the directory already exists   just as os makedirs got an exist ok flag starting from python 3 2 e g os makedirs path  exist ok True    Note  when i posted this answer none of the other answers mentioned exist ok

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You can use os listdir for this   import os if  dirName  in os listdir  parentFolderPath       print  Directory Exists

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Using try except and the right error code from errno module gets rid of the race condition and is cross-platform   import os import errno  def make sure path exists path       try          os makedirs path      except OSError as exception          if exception errno    errno EEXIST              raise   In other words  we try to create the directories  but if they already exist we ignore the error  On the other hand  any other error gets reported  For example  if you create dir  a  beforehand and remove all permissions from it  you will get an OSError raised with errno EACCES  Permission denied  error 13

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In Python3  os makedirs supports setting exist ok  The default setting is False  which means an OSError will be raised if the target directory already exists  By setting exist ok to True  OSError  directory exists  will be ignored and the directory will not be created   os makedirs path exist ok True    In Python2  os makedirs doesn t support setting exist ok  You can use the approach in heikki-toivonen s answer   import os import errno  def make sure path exists path       try          os makedirs path      except OSError as exception          if exception errno    errno EEXIST              raise

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I have put the following down  It s not totally foolproof though   import os  dirname    create me   try      os makedirs dirname  except OSError      if os path exists dirname             We are nearly safe         pass     else            There was an error on creation  so make sure we know about it         raise   Now as I say  this is not really foolproof  because we have the possiblity of failing to create the directory  and another process creating it during that period

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I would personally recommend that you use os path isdir   to test instead of os path exists      gt  gt  gt  os path exists   tmp dirname   True  gt  gt  gt  os path exists   tmp dirname filename etc   True  gt  gt  gt  os path isdir   tmp dirname filename etc   False  gt  gt  gt  os path isdir   tmp fakedirname   False   If you have    gt  gt  gt  dir   raw input          And a foolish user input       tmp dirname filename etc       You re going to end up with a directory named filename etc when you pass that argument to os makedirs   if you test with os path exists

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On Python   3 5  use pathlib Path mkdir   from pathlib import Path Path   my directory   mkdir parents True  exist ok True    For older versions of Python  I see two answers with good qualities  each with a small flaw  so I will give my take on it   Try os path exists  and consider os makedirs for the creation   import os if not os path exists directory       os makedirs directory    As noted in comments and elsewhere  there s a race condition  ndash  if the directory is created between the os path exists and the os makedirs calls  the os makedirs will fail with an OSError  Unfortunately  blanket-catching OSError and continuing is not foolproof  as it will ignore a failure to create the directory due to other factors  such as insufficient permissions  full disk  etc   One option would be to trap the OSError and examine the embedded error code  see Is there a cross-platform way of getting information from Python   s OSError    import os  errno  try      os makedirs directory  except OSError as e      if e errno    errno EEXIST          raise   Alternatively  there could be a second os path exists  but suppose another created the directory after the first check  then removed it before the second one  ndash  we could still be fooled    Depending on the application  the danger of concurrent operations may be more or less than the danger posed by other factors such as file permissions  The developer would have to know more about the particular application being developed and its expected environment before choosing an implementation   Modern versions of Python improve this code quite a bit  both by exposing FileExistsError  in 3 3       try      os makedirs  path to directory   except FileExistsError        directory already exists     pass      and by allowing a keyword argument to os makedirs called exist ok  in 3 2     os makedirs  path to directory   exist ok True     succeeds even if directory exists

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The relevant Python documentation suggests the use of the EAFP coding style  Easier to Ask for Forgiveness than Permission   This means that the code  try      os makedirs path  except OSError as exception      if exception errno    errno EEXIST          raise     else          print   nBE CAREFUL  Directory  s already exists     path   is better than the alternative  if not os path exists path       os makedirs path  else      print   nBE CAREFUL  Directory  s already exists     path   The documentation suggests this exactly because of the race condition discussed in this question  In addition  as others mention here  there is a performance advantage in querying once instead of twice the OS  Finally  the argument placed forward  potentially  in favour of the second code in some cases --when the developer knows the environment the application is running-- can only be advocated in the special case that the program has set up a private environment for itself  and other instances of the same program    Even in that case  this is a bad practice and can lead to long useless debugging  For example  the fact we set the permissions for a directory should not leave us with the impression permissions are set appropriately for our purposes  A parent directory could be mounted with other permissions  In general  a program should always work correctly and the programmer should not expect one specific environment

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Under Linux you can create directory in one line  import os os system  quot mkdir -p  0  quot  format  mydir

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I have put the following down  It s not totally foolproof though   import os  dirname    create me   try      os makedirs dirname  except OSError      if os path exists dirname             We are nearly safe         pass     else            There was an error on creation  so make sure we know about it         raise   Now as I say  this is not really foolproof  because we have the possiblity of failing to create the directory  and another process creating it during that period

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Check os makedirs    It makes sure the complete path exists    To handle the fact the directory might exist  catch OSError   If exist ok is False  the default   an OSError is raised if the target directory already exists    import os try      os makedirs    path to somewhere   except OSError      pass

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If you consider the following    os path isdir   tmp dirname     means a directory  path  exists AND is a directory  So for me this way does what I need  So I can make sure it is folder  not a file  and exists

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I use os path exists    here is a Python 3 script that can be used to check if a directory exists  create one if it does not exist  and delete it if it does exist  if desired    It prompts users for input of the directory and can be easily modified

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Check os makedirs    It makes sure the complete path exists    To handle the fact the directory might exist  catch OSError   If exist ok is False  the default   an OSError is raised if the target directory already exists    import os try      os makedirs    path to somewhere   except OSError      pass

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import os if os path isfile filename       print  file exists  else       Your code here       Where your code here is use the  touch  command   This will check if the file is there if it is not then it will create it

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I would personally recommend that you use os path isdir   to test instead of os path exists      gt  gt  gt  os path exists   tmp dirname   True  gt  gt  gt  os path exists   tmp dirname filename etc   True  gt  gt  gt  os path isdir   tmp dirname filename etc   False  gt  gt  gt  os path isdir   tmp fakedirname   False   If you have    gt  gt  gt  dir   raw input          And a foolish user input       tmp dirname filename etc       You re going to end up with a directory named filename etc when you pass that argument to os makedirs   if you test with os path exists

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In Python3  os makedirs supports setting exist ok  The default setting is False  which means an OSError will be raised if the target directory already exists  By setting exist ok to True  OSError  directory exists  will be ignored and the directory will not be created   os makedirs path exist ok True    In Python2  os makedirs doesn t support setting exist ok  You can use the approach in heikki-toivonen s answer   import os import errno  def make sure path exists path       try          os makedirs path      except OSError as exception          if exception errno    errno EEXIST              raise

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Check os makedirs    It makes sure the complete path exists    To handle the fact the directory might exist  catch OSError   If exist ok is False  the default   an OSError is raised if the target directory already exists    import os try      os makedirs    path to somewhere   except OSError      pass

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I have put the following down  It s not totally foolproof though   import os  dirname    create me   try      os makedirs dirname  except OSError      if os path exists dirname             We are nearly safe         pass     else            There was an error on creation  so make sure we know about it         raise   Now as I say  this is not really foolproof  because we have the possiblity of failing to create the directory  and another process creating it during that period

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Insights on the specifics of this situation  You give a particular file at a certain path and you pull the directory from the file path  Then after making sure you have the directory  you attempt to open a file for reading  To comment on this code    filename     my directory filename txt  dir   os path dirname filename     We want to avoid overwriting the builtin function  dir  Also  filepath or perhaps fullfilepath is probably a better semantic name than filename so this would be better written   import os filepath     my directory filename txt  directory   os path dirname filepath    Your end goal is to open this file  you initially state  for writing  but you re essentially approaching this goal  based on your code  like this  which opens the file for reading    if not os path exists directory       os makedirs directory  f   file filename     Assuming opening for reading  Why would you make a directory for a file that you expect to be there and be able to read    Just attempt to open the file   with open filepath  as my file      do stuff my file    If the directory or file isn t there  you ll get an IOError with an associated error number  errno ENOENT will point to the correct error number regardless of your platform  You can catch it if you want  for example   import errno try      with open filepath  as my file          do stuff my file  except IOError as error      if error errno    errno ENOENT          print  ignoring error because directory or file is not there      else          raise   Assuming we re opening for writing  This is probably what you re wanting   In this case  we probably aren t facing any race conditions  So just do as you were  but note that for writing  you need to open with the w mode  or a to append   It s also a Python best practice to use the context manager for opening files   import os if not os path exists directory       os makedirs directory  with open filepath   w   as my file      do stuff my file    However  say we have several Python processes that attempt to put all their data into the same directory  Then we may have contention over creation of the directory  In that case it s best to wrap the makedirs call in a try-except block   import os import errno if not os path exists directory       try          os makedirs directory      except OSError as error          if error errno    errno EEXIST              raise with open filepath   w   as my file      do stuff my file

[python] How can I safely create a nested directory?

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