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Full Discussion: Grep in regex
Top Forums UNIX for Beginners Questions & Answers Grep in regex Post 302987099 by rbatte1 on Monday 5th of December 2016 07:26:02 AM
Old 12-05-2016
I think you are over-simplifying the issue. I don't think that there is no way for certain to know if names exist with a regular expression. You cannot just assume that the last part of a domain name (the Top Level Domain) is a 2 or three characters only.

List of Internet top-level domains - Wikipedia


You might have to trim out the domain name from the full URL & perform a get to the real site to see if you connect. That might be the only way.
  • There may be a formal list of names of the TLDs
    • Each of those may have a list of valid names below them
      • Each of those may have a list of valid names below them
        • Each of those may have a list of valid names below them
          • Each of those may have a list of valid names below them ..............

You can see the problem. The list (if you could even build one) would be huge and would be frequently updating. Perhaps a DNS query would give you enough though.

Code:
host $extracted_domain_name >/dev/null
if [ $? -eq 0 ]
then
   echo "DNS entry exists"
else
   echo "It is an invalid domain"
fi

Does that help?




Robin
 

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Parity(3)						User Contributed Perl Documentation						 Parity(3)

NAME
String::Parity, setEvenParity, setOddParity, setSpaceParity, setMarkParity, isEvenParity, isOddParity isSpaceParity, isMarkParity, Even- Bytes, OddBytes, SpaceBytes, MarkBytes, showParity, showMarkSpace - Parity (odd/even/mark/space) handling functions SYNOPSIS
use String::Parity; use String::Parity qw(:DEFAULT /show/); DESCRIPTION
setEvenParity LIST Copies the elements of LIST to a new list and converts the new elements to strings of bytes with even parity. In array context returns the new list. In scalar context joins the elements of the new list into a single string and returns the string. setOddParity LIST Like setEvenParity function, but converts to strings with odd parity. setSpaceParity LIST Like setEvenParity function, but converts to strings with space (High bit cleared) parity. setMarkParity LIST Like setEvenParity function, but converts to strings with mark (High bit set) parity. EvenBytes LIST Returns the number of even parity bytes in the elements of LIST. OddBytes LIST Returns the number of odd parity bytes in the elements of LIST. SpaceBytes LIST Returns the number of space parity bytes in the elements of LIST. MarkBytes LIST Returns the number of mark parity bytes in the elements of LIST. isEvenParity LIST Returns TRUE if the LIST contains no byte with odd parity, FALSE otherwise. isOddParity LIST Returns TRUE if the LIST contains no byte with even parity, FALSE otherwise. isSpaceParity LIST Returns TRUE if the LIST contains no byte with mark parity, FALSE otherwise. isMarkParity LIST Returns TRUE if the LIST contains no byte with space parity, FALSE otherwise. showParity LIST Like setEvenParity function, but converts bytes with even parity to 'e' and other bytes to 'o'. The function showParity must be imported by a specialised import list. showMarkSpace LIST Like setEvenParity function, but converts bytes with space parity to 's' and other bytes to 'm'. The function showMarkSpace must be imported by a specialised import list. NOTES
Don't use this module unless you have to communicate with some old device or protocol. Please make your application 8 bit clean and use the internationally standardised ISO-8859-1 character set. AUTHOR
Winfried Koenig <win@in.rhein-main.de> SEE ALSO
perl(1), Exporter(1) perl v5.8.0 1996-12-10 Parity(3)
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