Parameter SubstitutionManipulating and/or expanding variables ${parameter}Same as $parameter, i.e., value of the variable parameter. In certain contexts, only the less ambiguous ${parameter} form works. May be used for concatenating variables with strings. your_id=${USER}-on-${HOSTNAME} echo "$your_id" # echo "Old \$PATH = $PATH" PATH=${PATH}:/opt/bin # Add /opt/bin to $PATH for duration of script. echo "New \$PATH = $
