Demo of string manipulation in Bash

bash-strings.sh

#!/bin/bash

# based on http://www.tldp.org/LDP/abs/html/string-manipulation.html

test=abcABC123ABCabc

echo "\${test} = ${test}"

echo && echo "Substrings:\${test:pos:length}"
echo "\${test:3} = ${test:3}" # ABC123ABCabc
echo "\${test: -3} = ${test: -3} " # abc
echo "\${test:3:3} = ${test:3:3}" # ABC
echo "\${test: -4:3} = ${test: -4:3}" # Cab

echo && echo "Front substring removal: \${test#pattern}"
echo "\${test#a*C} = ${test#a*C} (shortest match)" # 123ABCabc
echo "\${test##a*C} = ${test##a*C} (longest match)" # abc

echo && echo "Back substring removal: \${test%pattern}"
echo "\${test%C*c} = ${test%C*c} (shortest match)" # abcABC123AB 
echo "\${test%%C*c} = ${test%%C*c} (longest match)" # abcAB

echo && echo "Substring replacement: \${test/find/replace}"
echo "\${test/abc/xyz} = ${test/abc/xyz} (first instance)" # xyzABC123ABCabc
echo "\${test//abc/xyz} = ${test//abc/xyz} (all instances)" # xyzABC123ABCxyz
echo "\${test/#abc/xyz} = ${test/#abc/xyz} (front only)" # xyzABC123ABCabc
echo "\${test/%abc/xyz} = ${test/%abc/xyz} (back only)" # abcABC123ABCxyz