The user enters the argument to the script IP address, tell me how to check the correctness of the input of the IP address with the help of regulars?

  • eight
    IP v4, IP v6, IP v4 & v6? - MaxU
  • four
    What are the general requirements for a correct IP address as a whole? - andreymal
  • What for?! Is there really not enough normal utility to do this? man ipcalc , man ipv6calc . - 0andriy

4 answers 4

 echo "$IP" | grep -E "([0-9]{1,3}[\.]){3}[0-9]{1,3}"

if there is enough testing of four three-digit numbers through a point, without checking for exceeding 255 and validity and compliance with the "white" - "gray" ranges.

You can also make whois "$IP" , in Russian localization, to an invalid address, whois always returns:

 Нет whois-сервера для объектов данного вида.

this works for both local addresses and domain names.

  • Comments are not intended for extended discussion; conversation moved to chat . - PashaPash ♦

a fairly correct expression for checking ipv4-addresses:

$ echo "ipv4-адрес" | grep -Eq '^((25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9]?[0-9])\.){3}(25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9][0-9]?)$'

does not miss:

 1.2.3.0 0.0.0.256 xyzt 1...1 1.1.1 1.1.1.1.1 1000.1.1.1 1.2.3.04 и т.п.

so that the addresses, in the last octet of which zero is written (see the discussion in the comments), should be skipped, should the last one be passed ? slightly to the left:

$ echo "ipv4-адрес" | grep -Eq '^((25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9]?[0-9])\.){3}(25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9]?[0-9])$'

explanation:

  • -E is a grep program option that enables extended regexp mode. in this case it is used only in order not to overload the expression with backslashes
  • -q - option of the grep program, thanks to which the program will not write anything to stdout , but will only return the return code (there is a match - it will return 0, otherwise - it will return non-zero)
  • ^...$ - binding to the beginning and end of the line
  • (...) - group
  • (...){3} - the group should repeat exactly three times.
  • (выражение1|выражение2|...) - must match either выражение1 or выражение2 or ...
  • [...] - any of the listed characters ("set")
  • [0-5] - any of the numbers from zero to five
  • x? - the character x can occur zero or once (in this case, the “character” can be both a group (...) and a character set [...]
  • \. - the “dot” character (without a backslash, the dot is a quantifier that matches any (one) character)
  • sure that 1.2.3.0 is not a valid ip-address? - ArcherGodson
  • @ArcherGodson whois 1.2.3.0 >> For details, refer to the APNIC Whois Database via WHOIS.APNIC.NET or wq.apnic.net/apnic-bin/whois.pl " - Nick Volynkin ♦
  • # whois 1.2.3.0% [whois.apnic.net]% Whois data copyright terms apnic.net/db/dbcopyright.html% Information related to '1.2.3.0 - 1.2.3.255'% Abuse contact for '1.2.3.0 - 1.2 .3.255 'is' abuse@apnic.net' inetnum: 1.2.3.0 - 1.2.3.255 netname: Debogon-prefix descr: APNIC Debogon Project descr: APNIC Pty Ltd ... change huiz - ArcherGodson
  • Can I go on the other hand, 192.168.100.0 is not exactly valid? and 192.168.1.1? - ArcherGodson
  • @ArcherGodson, 1.2.3.0 and 192.168.100.0 - yes, I think they are invalid for a host. 192.168.1.1 - thanks, corrected typo. - aleksandr barakin

You can make sure that the IP-address is recorded correctly, you can use such a regular schedule ( taken from here ). This expression allows both IPv4 and IPv6 addresses.

 (([0-9a-fA-F]{1,4}:){7,7}[0-9a-fA-F]{1,4}|([0-9a-fA-F]{1,4}:){1,7}:|([0-9a-fA-F]{1,4}:){1,6}:[0-9a-fA-F]{1,4}|([0-9a-fA-F]{1,4}:){1,5}(:[0-9a-fA-F]{1,4}){1,2}|([0-9a-fA-F]{1,4}:){1,4}(:[0-9a-fA-F]{1,4}){1,3}|([0-9a-fA-F]{1,4}:){1,3}(:[0-9a-fA-F]{1,4}){1,4}|([0-9a-fA-F]{1,4}:){1,2}(:[0-9a-fA-F]{1,4}){1,5}|[0-9a-fA-F]{1,4}:((:[0-9a-fA-F]{1,4}){1,6})|:((:[0-9a-fA-F]{1,4}){1,7}|:)|fe80:(:[0-9a-fA-F]{0,4}){0,4}%[0-9a-zA-Z]{1,}|::(ffff(:0{1,4}){0,1}:){0,1}((25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])\.){3,3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])|([0-9a-fA-F]{1,4}:){1,4}:((25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])\.){3,3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9]))|((25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])\.){3,3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])

Here is an example script for the command interpreter.

 ip_regex='(([0-9a-fA-F]{1,4}:){7,7}[0-9a-fA-F]{1,4}|([0-9a-fA-F]{1,4}:){1,7}:|([0-9a-fA-F]{1,4}:){1,6}:[0-9a-fA-F]{1,4}|([0-9a-fA-F]{1,4}:){1,5}(:[0-9a-fA-F]{1,4}){1,2}|([0-9a-fA-F]{1,4}:){1,4}(:[0-9a-fA-F]{1,4}){1,3}|([0-9a-fA-F]{1,4}:){1,3}(:[0-9a-fA-F]{1,4}){1,4}|([0-9a-fA-F]{1,4}:){1,2}(:[0-9a-fA-F]{1,4}){1,5}|[0-9a-fA-F]{1,4}:((:[0-9a-fA-F]{1,4}){1,6})|:((:[0-9a-fA-F]{1,4}){1,7}|:)|fe80:(:[0-9a-fA-F]{0,4}){0,4}%[0-9a-zA-Z]{1,}|::(ffff(:0{1,4}){0,1}:){0,1}((25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])\.){3,3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])|([0-9a-fA-F]{1,4}:){1,4}:((25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])\.){3,3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9]))|((25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])\.){3,3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])' if echo "$param" | egrep -q "$ip_regex"; then // теперь в переменной $param что-то похожее на IP-адрес ... fi 
     rexp='(?:(?:\d{1,2}|1\d{,2}|2[0-4]?\d?|25?[0-5]?)\.){3}(?:\d{1,2}|1\d{,2}|2[0-4]?\d?|25?[0-5]?)'