I coincidentally found out that I cannot change the actual directory from within a python-code. My Test-Program is as follows:
from os import system
def sh(script):
system("bash -c '%s'" % script)
sh("cd /home")
sh("pwd")
The output of pwd is not /home, but the directory where the code above lives.
Can someone explain why this happens?
The problem is that you execute shell commands instead of actually changing the directory using os.chdir()
Each os.system() call executes the given command in a new shell - so the script's working directory is not affected at all.
The directory actually is changed, but in another process, the child of your script. There's one simple rule to remember: a child can never affect the environment (PATH, CWD etc) of its parent.
sh("cd /home")
sh("pwd")
^ this spawns 2 separate shells, try:
sh("cd /home; pwd")
When you run sh function you spawn a new bash process which then changes current directory and exits. Then you spawn a new process which knows nothing about what happened to the first bash process. Its current directory is, again, set to the home directory of the current user.
To change Python process' current working directory use
os.chdir("blah")`
Each sh( ) call is generating a different shell, so you are affecting the shell's working directory, not python's. To change pythons working directory, use chdir()
