#!/bin/bash# substring-extraction.shString=23skidoo1#      012345678    Bash#      123456789    awk# Note different string indexing system:# Bash numbers first character of string as '0'.# Awk  numbers first character of string as '1'.echo ${String:2:4} # position 3 (0-1-2), 4 characters long                                         # skid# The awk equivalent of ${string:pos:length} is substr(string,pos,length).echo | awk '{ print substr("'"${String}"'",3,4)      # skid}'#  Piping an empty "echo" to awk gives it dummy input,#+ and thus makes it unnecessary to supply a filename.exit 0