1*aeb91fd3Santonsetenv FOO 1 2*aeb91fd3Santonecho $FOO 3*aeb91fd3Santonunsetenv FOO 4*aeb91fd3Santonsetenv | grep FOO || echo ok 5*aeb91fd3Santonsetenv FOO 1 6*aeb91fd3Santonsetenv FOOFOO 2 7*aeb91fd3Santonecho $FOO $FOOFOO 8*aeb91fd3Santonunsetenv FOO* 9*aeb91fd3Santonsetenv | grep FOO || echo ok 10