returns part of string

substr.bash

# returns part of string
# @param string input
# @param string startoffset
# @param string number of characters
#
# usage: substr foobar 0 3                                (outputs 'foo')
#        echo "foobar" | substr 0 3                       (outputs 'foo')
#        short="$( substr "foobar" 0 3 )"; echo "$short"  (outputs 'foo')

function substr(){
  if [[ -n "$3" ]]; then echo "${1:$2:$3}"; 
  else cat - | while read line; do a="$line"; b="$1"; c="$2"; echo "${a:b:c}"; done; fi;
}