python Change the scripts working directory to the script s own directory

Question

I run a python shell from crontab every minute              home udi foo bar py    home udi foo has some necessary subdirectories  like  home udi foo log and  home udi foo config  which  home udi foo bar py refers to   The problem is that crontab runs the script from a different working directory  so trying to open   log bar log fails   Is there a nice way to tell the script to change the working directory to the script s own directory  I would fancy a solution that would work for any script location  rather than explicitly telling the script where it is   EDIT   os chdir os path dirname sys argv 0      Was the most compact elegant solution  Thanks for your answers and explanations

User · Answer

Don t do this   Your scripts and your data should not be mashed into one big directory   Put your code in some known location  site-packages or  var opt udi or something  separate from your data   Use good version control on your code to be sure that you have current and previous versions separated from each other so you can fall back to previous versions and test future versions   Bottom line  Do not mingle code and data   Data is precious   Code comes and goes   Provide the working directory as a command-line argument value   You can provide a default as an environment variable   Don t deduce it  or guess at it   Make it a required argument value and do this   import sys import os working  os environ get  WORKING DIRECTORY    some default   if len sys argv   gt  1  working   sys argv 1  os chdir  working     Do not  assume  a directory based on the location of your software   It will not work out well in the long run

User · Answer

This will change your current working directory to so that opening relative paths will work   import os os chdir   home udi foo     However  you asked how to change into whatever directory your Python script is located  even if you don t know what directory that will be when you re writing your script   To do this  you can use the os path functions   import os  abspath   os path abspath   file    dname   os path dirname abspath  os chdir dname    This takes the filename of your script  converts it to an absolute path  then extracts the directory of that path  then changes into that directory

User · Answer

Change your crontab command to             cd  home udi foo     exit 1    bar py    The       starts a sub-shell that your crond executes as a single command  The    exit 1 causes your cronjob to fail in case that the directory is unavailable   Though the other solutions may be more elegant in the long run for your specific scripts  my example could still be useful in cases where you can t modify the program or command that you want to execute

User · Answer

You can get a shorter version by using sys path 0    os chdir sys path 0     From http   docs python org library sys html sys path     As initialized upon program startup  the first item of this list    path 0   is the directory containing the script that was used to   invoke the Python interpreter

[python] python: Change the scripts working directory to the script's own directory

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