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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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LEARN ABOUT CENTOS

rescan-scsi-bus.sh

RESCAN-SCSI-BUS.SH(1)						   User Commands					     RESCAN-SCSI-BUS.SH(1)

NAME

       rescan-scsi-bus.sh - script for adding and removing SCSI devices without rebooting

SYNOPSIS

       rescan-scsi-bus.sh [options] [host [host ...]]

OPTIONS

       -a, --alltargets
	      scan all targets, not just currently existing [default: disabled]

       -d     enable debug			 [default: 0]

       -l     activates scanning for LUNs 0--7	 [default: 0]

       -L NUM activates scanning for LUNs 0--NUM [default: 0]

       -w, --wide
	      scan for target device IDs 0--15	 [default: 0--7]

       -c     enables scanning of channels 0 1	 [default: 0 / all detected ones]

       -r, --remove
	      enables removing of devices	 [default: disabled]

       -f, --flush
	      flush failed multipath devices	 [default: disabled]

       -i, --issue-lip
	      issue a FibreChannel LIP reset	 [default: disabled]

       -u, --update
	      look for existing disks that have been remapped

       -s, --resize
	      look for resized disks and reload associated multipath devices, if applicable

       --forcerescan
	      rescan existing devices

       --forceremove
	      remove and readd every device (DANGEROUS)

       --nooptscan
	      don't stop looking for LUNs is 0 is not found

       --color
	      use coloured prefixes OLD/NEW/DEL

       --hosts=LIST
	      scan only host(s) in LIST

       --channels=LIST
	      scan only channel(s) in LIST

       --ids=LIST
	      scan only target ID(s) in LIST

       --luns=LIST
	      scan only lun(s) in LIST

       --sync, --nosync
	      issue a sync / no sync [default: sync if remove]

       --attachpq3
	      tell kernel to attach sg to LUN 0 that reports PQ=3

       --reportlun2
	      tell kernel to try REPORT_LUN even on SCSI2 devices

       --largelun
	      tell kernel to support LUNs > 7 even on SCSI2 devs

       --sparselun
	      tell kernel to support sparse LUN numbering

	      Host numbers may thus be specified either directly on cmd line (deprecated) or or with the --hosts=LIST parameter (recommended).

       LIST: A[-B][,C[-D]]... is a comma separated list of single values and ranges (No spaces allowed.)

SEE ALSO

       rescan-scsi-bus.sh Homepage: http://www.garloff.de/kurt/linux/#rescan-scsi

       sg3_utils Homepage: http://sg.danny.cz/sg

rescan-scsi-bus.sh 1.57 					    leden 2014						     RESCAN-SCSI-BUS.SH(1)
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