isnum - Man Page

Return code telling whether the input string is numerical

isnum is a utility for identifying and classifying an input string. <B>isnum</B> returns an integer code depending on how it identifies the input number: 0: string is not any sort of number 1: String is an integer 2: String is a floating point number 3: String is a hh:mm:ss.ss time 4: String is a yyyy-mm-dd date