DIRECTORY=/usr/local
LS=ls
CMD="$LS $DIRECTORY"
$CMD     # Note how the command is executed indirectly.


# Add a -1 (one) command-line option.
DIRECTORY=/usr/local
LS=ls
LS_OPTS="-1"
CMD="$LS $LS_OPTS $DIRECTORY"
$CMD


# Even more indirect script.
DIRECTORY=/usr/local
LS=ls
LS_OPTS="-1"
LS_CMD="$LS $LS_OPTS"
CMD="$LS_CMD $DIRECTORY"
$CMD