Cut

You can get a substring in a range using the cut command. This command takes a flag -c followed by a range of 1 indexed characters to return, described in the format -cI-N where I is the ith character to start from and N is the nth to strip to, this also includes the character that you strip from.

$ echo "STRING" | cut -c2-4 # => TRI

You can get a substring until the end of a string by leaving the second number (N) empty.

$ echo "STRING" | cut -c2- # => TRING