tree d34db65ce88b141c2b737a0767084a0899f17719
parent 9d3262b2127eb2dc3f22b38d596136f08bb0fee5
author Andrew Ruder <andrew.ruder@elecsyscorp.com> 1382486854 -0500
committer Tom Rini <trini@ti.com> 1383921504 -0500

cmd_nvedit.c: Add env exists command

env exists is a way to test (in hush) if an environment variable
exists.  A workaround existed using printenv but this new command
doesn't require all the stdout/stderr redirection to prevent
printing information to the screen.

Example:
$ set testexists 1
$ env exists testexists && echo "yes"
yes
$ env exists testexists || echo "no"
$ set testexists
$ env exists testexists && echo "yes"
$ env exists testexists || echo "no"
no
$

Signed-off-by: Andrew Ruder <andrew.ruder@elecsyscorp.com>