Program Environments / Variables

[nixpulvis]

POSIX shell scripts like most programs have a notion of bindings with scope. We need to implement the syntax fo assigning (FOO=1) and referencing ($FOO) variables. As part of loading a program it's default environment should be loaded appropriately. The environment variable $ENV denotes the complete working environment for a POSIX program.

• Special Parameters #54
• Positional Parameters #55

Related to #43.

[nixpulvis]

First pass implementation merged in #51.

[nixpulvis]

Key issue we need to fix is related to the scope of variables and their assignment, e.g X=1 echo $X should not print 1 as it does today.

Captured in a few preliminary tests here;

oursh/tests/posix.rs

Lines 125 to 128 in b064528

	assert_posix!("X=1; echo $X", "1\n");
	assert_posix!("X=1 echo $X", "\n");
	assert_posix!("X=1; printenv X", "\n");
	assert_posix!("X=1 printenv X", "1\n");