Shell ${} and #,% Usage

In shell scripts, symbols are very usefull to handle strings in variables. Next list some frequently used methods of getting specified strings from variables.

${var##*str}               get string after the last str in $var

${var#*str}                get string after the 1st str in $var

${var%%str*}              get string before the 1st str in $var

${var%str*}                get string before the last str in $var

${#var}                       get how many bytes in $var.

E.g.

var=abcddcba

echo ${var##*c}        get "ba"

echo ${var#*c}          get "ddcba"

echo ${var%%c*}        get "ab"

echo ${var%c*}          get "abcdd"

echo ${#var}              get "8"