check if environment variable is already set
58433
What's a concise way to check that environment variables are set in a Unix shell script?
100513
import environment variables in a bash script
54838
determine shell in script during runtime
3146
What are PATH and other environment variables, and how can I set or use them?
19329
How to check if directory exists in %PATH%?
22578
How do I set an environment variable on the command line and have it appear in commands?
53507
Test if executable exists in Python?
93046
How to see if the directory exists?
113748
Is it possible to change the Environment of a parent process in Python?
63101
How to set environment variable in systemd service?
40229
How do I check if a variable exists?
81183
How can I set env variables so that KDE recognizes them?
139705
Setting or modifying a (system wide) environment variable in cmd.exe
151216
Is there a nice way to set directory/project local environment variables?
150358
How to check whether a particular directory is mounted?
65962
How to compare a program's version in a shell script?
20256
How do I set environment variables from Java?