SHELL

split and get last

Use rev command altogether with cut command as follows:
echo "a1 a2 a3 a4 a5" | rev | cut -d ' ' -f '1' | rev
#rev reverses string, then you cut from 2th field to end and reverse back

split string on last element

stringCutted = myString.Substring(myString.LastIndexOf("/")+1);