#!/bin/bash echo '##### test of variable #####' echo VAR=onetwothree VAR=onetwothree echo ' '\$VAR is: $VAR echo ' '\$\{\#VAR\} is: ${#VAR} echo echo ' ## parameter substitutions ##' echo ' When VAR2=' VAR2= echo ' : ${VAR2:=$VAR}' : ${VAR2:=$VAR} echo ' $VAR2 is: '$VAR2 echo ' When VAR2=four' VAR2=four echo ' : ${VAR2:=$VAR}' : ${VAR2:=$VAR} echo ' $VAR2 is: '$VAR2 echo echo ' When VAR2=' VAR2= echo ' VAR3=${VAR2:-$VAR}' VAR3=${VAR2:-$VAR} echo ' $VAR3 is:' $VAR3 echo ' When VAR2=four' VAR2=four echo ' VAR3=${VAR2:-$VAR}' VAR3=${VAR2:-$VAR} echo ' $VAR3 is:' $VAR3 echo echo ' When VAR2=' VAR2= echo ' VAR3=${VAR2:+$VAR}' VAR3=${VAR2:+$VAR} echo ' $VAR3 is:' $VAR3 echo ' When VAR2=four' VAR2=four echo ' VAR3=${VAR2:+$VAR}' VAR3=${VAR2:+$VAR} echo ' $VAR3 is:' $VAR3 echo echo ' When VAR2=' VAR2= echo ' (VAR3=${VAR2:?$VAR} ; echo " \$VAR3 is:" $VAR3)' (VAR3=${VAR2:?$VAR} ; echo " \$VAR3 is:" $VAR3) echo ' $? is:' $? echo ' When VAR2=four' VAR2=four echo ' (VAR3=${VAR2:?$VAR} ; echo " \$VAR3 is:" $VAR3)' (VAR3=${VAR2:?$VAR} ; echo " \$VAR3 is:" $VAR3) echo ' $? is:' $? echo echo ' VAR=one; VAR2=; VAR3=three' VAR=one; VAR2=; VAR3=three echo ' ${!VAR*} is:' ${!VAR*} echo echo ' ## replace functions ##' echo ' VAR=onetwothree' VAR=onetwothree echo ' ${VAR/two/four} is:' ${VAR/two/four} echo ' $VAR is: ' $VAR echo ' ${VAR/two} is:' ${VAR/two} echo ' ${VAR/t/xx} is:' ${VAR/t/xx} echo echo ' ${VAR^t} is:' ${VAR^t} echo ' ${VAR^^t} is:' ${VAR^^t} echo ' ${VAR^^} is:' ${VAR^^} echo ' VARUP=ONETWOTHREE' VARUP=ONETWOTHREE echo ' ${VARUP,T} is:' ${VARUP,T} echo ' ${VARUP,,T} is:' ${VARUP,,T} echo ' ${VARUP,,} is:' ${VARUP,,} echo echo ' ${VAR#one*t} is:' ${VAR#one*t} echo ' ${VAR##one*t} is:' ${VAR##one*t} echo ' ${VAR%t*ee} is:' ${VAR%t*ee} echo ' ${VAR%%t*ee} is:' ${VAR%%t*ee} echo echo ' ${VAR: 0: 3} is:' ${VAR: 0: 3} echo ' ${VAR: 2: 3} is:' ${VAR: 2: 3} echo ' ${VAR: 2} is:' ${VAR: 2} echo ' ${VAR: -4: 3} is:' ${VAR: -4: 3} echo ' ${VAR: -4} is:' ${VAR: -4} echo ' ${VAR: -1} is:' ${VAR: -1} echo exit 0