Setting environment variables for multiple commands in bash one-liner

Question

Let's say I have following command

$> MYENVVAR=myfolder echo $MYENVVAR && MYENVVAR=myfolder ls $MYENVVAR

I mean that MYENVVAR=myfolder repeats

Is it possible to set it once for both "&&" separated commands while keeping the command on one line?

Answer 1

Assuming you actually need it as an environment variable (even though the example code does not really need an environment variable; some shell variables are not environment variables):

(export MYENVVAR=myfolder; echo $MYENVVAR && ls $MYENVVAR) 

If you don't need it as an environment variable, then:

(MYENVVAR=myfolder; echo $MYENVVAR && ls $MYENVVAR) 

The parentheses create a sub-shell; environment variables (and plain variables) set in the sub-shell do not affect the parent shell. In both commands shown, the variable is set once and then used twice, once by each of the two commands.