System tasks.
WHAT PYTHON CAN DO
Read environment variables List and manipulate files Run other programs Report system information
WHEN TO RUN ANOTHER PROGRAM
When a tool already does the job well.
WHAT TO USE
The subprocess facilities, rather than older or simpler alternatives.
WHAT TO NEVER DO
Build a command by joining strings containing values from outside.
WHY
That is command injection, and it gives the caller control of your server.
WHAT TO DO INSTEAD
Pass the command and its arguments as a list, without a shell.
WHAT TO ALWAYS SET
A timeout, so a hung command does not hang your script.
WHAT TO CAPTURE
Output and exit status.
WHAT TO CHECK
The exit status, before assuming success.
WHAT TO HANDLE
The command not existing The command failing Unexpected output
WHAT TO BE CAREFUL WITH ON SHARED HOSTING
Commands requiring privileges you do not have Resource-intensive operations
WHAT TO PREFER
A Python library over running an external command, where one exists.
