Reading and writing environment variables in Python

Question

My python script which calls many python functions and shell scripts  I want to set a environment variable in Python  main calling function  and all the daughter processes including the shell scripts to see the environmental variable set   I need to set some environmental variables like this   DEBUSSY 1 FSDB 1   1 is a number  not a string  Additionally  how can I read the value stored in an environment variable   Like DEBUSSY FSDB in another python child script

User · Answer

Use os environ str DEBUSSY   for both reading and writing  http   docs python org library os html os environ    As for reading  you have to parse the number from the string yourself of course

User · Answer

First things first    reading books is an excellent approach to problem solving  it s the difference between band-aid fixes and long-term investments in solving problems  Never miss an opportunity to learn   D  You might choose to interpret the 1 as a number  but environment variables don t care  They just pass around strings      The argument envp is an array of character pointers to null-    terminated strings  These strings shall constitute the    environment for the new process image  The envp array is    terminated by a null pointer     From environ 3posix     You access environment variables in python using the os environ dictionary-like object    gt  gt  gt  import os  gt  gt  gt  os environ  HOME     home sarnold   gt  gt  gt  os environ  PATH     home sarnold bin  usr local sbin  usr local bin  usr sbin  usr bin  sbin  bin  usr games   gt  gt  gt  os environ  PATH     os environ  PATH        silly    gt  gt  gt  os environ  PATH     home sarnold bin  usr local sbin  usr local bin  usr sbin  usr bin  sbin  bin  usr games  silly

User · Answer

If you want to pass global variables into new scripts  you can create a python file that is only meant for holding global variables  e g  globals py   When you import this file at the top of the child script  it should have access to all of those variables   If you are writing to these variables  then that is a different story  That involves concurrency and locking the variables  which I m not going to get into unless you want

User · Answer

Try using the os module   import os  os environ  DEBUSSY      1  os environ  FSDB      1     Open child processes via os system    popen   or fork   and execv    someVariable   int os environ  DEBUSSY      See the Python docs on os environ  Also  for spawning child processes  see Python s subprocess docs

[python] Reading and writing environment variables in Python?

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