Terminal preview does not accept environment variables from parent process

[ChrisKnue-MSFT]

Windows Terminal version

1.18.1421.0

Windows build number

10.0.22631.0

Other Software

No response

Steps to reproduce

Create a batch file "test.bat" with contents

echo %TEST%
pause

open cmd terminal profile
run SET TEST=wow
run wt test.bat
run ./test.bat

Expected Behavior

New terminal window should open up with output (this is the behavior in 1.16)

>echo wow
wow
>pause
press any key to continue . . .

Then outputs in parent window

>echo wow
wow
>pause
press any key to continue . . .

Actual Behavior

New terminal window is opened with output

>echo
ECHO is on.
>pause
Press any key to continue . . .

Then outputs in parent window

>echo wow
wow
>pause
press any key to continue . . .

[DHowett]

Ah, indeed!

With WT transitioning to a long-lived single process model like Explorer, we're evaluating a stance that all tabs and panes receive a completely new environment block on creation. That's the only way--apart from a risky three-way merge--to ensure that applications get up-to-date environment variables without requiring everything run through Terminal to actively reconstruct and merge its own envrionment. In short, inheritance is in tension with #1125 and #7239.

The move to that single-process model has made it somewhat difficult to maintain a chain of custody for the env. block in any way other than to construct a new one! There is probably something we could do with the wt remote control to send over environment variables that are "important," but that will require some doing.

[DHowett]

This was already a bit "wacky" for window grouping, even in Preview 1.16 (and 1.15, 1.14, ...):

SET TEST=wow
wt -w 0 cmd

has different environment block behavior than...

SET TEST=wow
wt -w -1 cmd

Between the two, they are now at the very least consistent as of 1.18 😄

[carlos-zamora]

@ChrisKnue-MSFT Thanks for filing! Going to close this based on Dustin's responses.

[timmydo]

We have hundreds of developers relying on windows terminal for running about 6 tabs of applications to run our platform. Not propagating environment variables is a pretty large breaking change--I hope you will provide a workaround for passing environment variables to new tabs or at least give us some time to rearchitect things before the preview becomes the standard version. @DHowett

[DHowett]

(I'm gonna reopen this and mark it for discussion among the team.)

There's roughly one quarter of a year until this ships broadly, which is the big win we get from having a preview channel 😄

[zadjii-msft]

quick notes

• collect the env when wt is run. Package that up with the CommandlineArgs to send to the monarch
• add a --flag to tell NewTab/SplitPane to use those env vars instead of the regenerated ones
• don't just keep using those vars for future tabs/panes

[DHowett]

Maybe the --flag should be to disable inheritance