Is there a way to change the environment variables of another process in Unix?

Question

On Unix, is there any way that one process can change another\'s environment variables (assuming they\'re all being run by the same user)? A general solution would be best,

Answer 1

It seems that putenv doesn't work now, but setenv does. I was testing the accepted answer while trying to set the variable in the current shell with no success

$] sudo gdb -p $$
(gdb) call putenv("TEST=1234")
$1 = 0
(gdb) call (char*) getenv("TEST")
$2 = 0x0
(gdb) detach
(gdb) quit
$] echo "TEST=$TEST"
TEST=

and the variant how it works:

$] sudo gdb -p $$
(gdb) call (int) setenv("TEST", "1234", 1)
$1 = 0
(gdb) call (char*) getenv("TEST")
$2 = 0x55f19ff5edc0 "1234"
(gdb) detach
(gdb) quit
$] echo "TEST=$TEST"
TEST=1234