shell script split string into array and get last element code example

Example 1: bash get last field in line

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

Example 2: bash split variable by delimiter

IFS='|' read -r -a arrayName <<< "$variable"