The telephone INPUT tag allows you to request telephone numbers in your HTML forms.
DTD: HTML5: At this time, there are no browsers that really support the input type telephone tag. You can still use this input type to collect phone numbers and just use a script to validate the phone number. In one sense all browsers support the input type telephone tag because they all display it as a text field.
Tools category section below includes annotated links to Web authoring / HTML editors, reviews, and other resources, along with links to HTML reference charts, cleanup and conversion tools, automated HTML tools, and HTML validators. Note that some tools include HTML editors will generate the HTML markup for you, such as Dreamweaver and Front Page above, and so will publishing programs and content management systems (CMS).
You can also watch a video to see how the visual regex tester works.
Regular expressions, by definition, are string patterns that describe text.
The following bash script contains a bash function which returns true if it is passed a valid IP address and false otherwise.
In bash speak true means it exits with a zero status, anything else is false.
The status of a command/function is stored in the bash variable "$? variable so that rather than parsing words as whitespace separated items, bash parses them as dot separated.