问题
Running os.path.expandvars
fails for some env variables. Seems too basic to be real.
$ echo $HOSTTYPE
x86_64
$ echo $HOME
/labhome/eladw
$ python -c 'import os; print os.path.expandvars("$HOSTTYPE")'
$HOSTTYPE
$ python -c 'import os; print os.path.expandvars("$HOME")'
/labhome/eladw
Any idea what I'm missing (I am running python 2.7)?
回答1:
Environment variables set in a shell are not automatically exported to subprocesses. Just because your shell has a HOSTTYPE
variable, doesn't mean this is variable is visible to subprocesses.
Export the variable first:
$ export HOSTTYPE
You can combine setting and exporting a variable in one step with:
$ export HOSTTYPE=x86_64
Demo:
$ HOSTTYPE=x86_64
$ python -c 'import os; print os.path.expandvars("$HOSTTYPE")'
$HOSTTYPE
$ export HOSTTYPE
$ python -c 'import os; print os.path.expandvars("$HOSTTYPE")'
x86_64
See Difference between environment variables and exported environment variables in bash.
来源:https://stackoverflow.com/questions/50857962/python-os-path-expandvars-only-works-for-some-variables