substr(EXPR,OFFSET,LEN)

     substr(EXPR,OFFSET)

             Extracts a substring out of  EXPR  and  returns  it.
             First  character  is at offset 0, or whatever you've
             set $[ to.  If OFFSET is negative, starts  that  far
             from  the  end  of  the  string.  If LEN is omitted,
             returns everything to the end of  the  string.   You
             can use the substr() function as an lvalue, in which
             case EXPR must be an lvalue.  If  you  assign  some-
             thing  shorter than LEN, the string will shrink, and
             if you assign something longer than LEN, the  string
             will grow to accommodate it.  To keep the string the
             same length you may need to pad or chop  your  value
             using sprintf().