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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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UPSCLI_LIST_START(3)						    NUT Manual						      UPSCLI_LIST_START(3)

NAME
upscli_list_start - begin multi-item retrieval from a UPS SYNOPSIS
#include <upsclient.h> int upscli_list_start(UPSCONN_t *ups, int numq, const char **query) DESCRIPTION
The upscli_list_start() function takes the pointer ups to a UPSCONN_t state structure, and the pointer query to an array of numq query elements. It builds a properly-formatted request from those elements and transmits it to upsd(8). Upon success, the caller must call upscli_list_next(3) to retrieve the elements of the list. Failure to retrieve the list will most likely result in the client getting out of sync with the server due to buffered data. USES
This function implements the "LIST" command in the protocol. As a result, you can use it to request many different things from the server. Some examples are: o LIST UPS o LIST VAR <ups> o LIST RW <ups> o LIST CMD <ups> o LIST ENUM <ups> <var> o LIST RANGE <ups> <var> QUERY FORMATTING
To see the list of variables on a UPS called su700, the protocol command would be LIST VAR su700. To start that list with this function, you would populate query and numq as follows: int numq; const char *query[2]; query[0] = "VAR"; query[1] = "su700"; numq = 2; All escaping of special characters and quoting of elements with spaces are handled for you inside this function. ERROR CHECKING
This function checks the response from upsd(8) against your query. If it is not starting a list, or is starting the wrong type of list, it will return an error code. When this happens, upscli_upserror(3) will return UPSCLI_ERR_PROTOCOL. RETURN VALUE
The upscli_list_start() function returns 0 on success, or -1 if an error occurs. SEE ALSO
upscli_fd(3), upscli_get(3), upscli_readline(3), upscli_sendline(3), upscli_ssl(3), upscli_strerror(3), upscli_upserror(3) Network UPS Tools 05/31/2012 UPSCLI_LIST_START(3)
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