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Manual Reference Pages  -  IDNCHECK (1)


idncheck - check an internationalized domain name


Local Encoding
See Also


idncheck [options..] name


idncheck command checks an internationalized domain name. It tries to convert name to A-labels with various checks defined by IDNA2008-Protocol.

If the given name is a valid internationalized domain name, idncheck outputs the message:


to standard error and returns with exit code 0. Note that also traditional ASCII domain names are considered valid.

If the name is not valid, it outputs the reason (e.g. ‘‘invalid encoding’’) to standard error and returns with exit code 2. If an internal error such as memory exhaustion is caused, idncheck outputs the reason to standard error and then returns with exit code 3.

Unless -noconf (or -C) option is given, idncheck reads a configuration file (/usr/local/etc/idn2.conf, ~/.idn2rc or a file specified by an option) and performs conversions according to the parameters specified in the file.


-in in-code, -i in-code
  Specify the encoding name of the domain name specified as an argument. Any of the following encoding names can be recognized.
o Any encoding names which iconv_open() accepts
o Punycode
o UTF-8
o Any alias names for the above, defined by the encoding alias file.
The encoding defaults to the value of the environment variable ‘‘IDN_LOCAL_CODESET’’ or, if it is not set, an encoding determined from the locale information.
-conf file, -c file
  Specify the path of idnkit configuration file. If not specified, the default path (/usr/local/etc/idn2.conf or ~/.idn2rc) unless -noconf (or -C) option is specified.
-noconf, -C
  Suppress reading a configuration file.
-registration, -g (default)
  Use domain name registration protocol. This is the default behavior.
-lookup, -l
  Use domain name lookup protocol.
-nomap, -M
  Don’t perform the ‘‘map’’ action. This is the same as ‘‘-skip map’’.
-skip action,...
  Skip actions. the following action names are recognized:
map mappings
asclower convert ASCII uppercase letters to lowercase
rtconv conversion from Punycode to Unicode for round trip check
prohcheck prohibited code point check
unascheck unassigned code point check
nfccheck NFC conformance check
prefcheck ACE prefix check
hyphcheck hyphen check
combcheck combining character check
ctxjcheck CONTEXTJ code point check
ctxocheck CONTEXTO code point check for domain name registration protocol.
ctxolitecheck CONTEXTO code point check for domain name lookup protocol.
bidicheck Bidi check.
idnconv conversion to Punycode
lencheck label length check
rtcheck round trip check
-localcheck file, -e file
  Also perform code point check using file. Using the local check feature, you can check whether a domain name consists of code points allowed by a particular registry. The format of file is explained in idn_setlocalcheckfile(3).
-quiet, -q
  Suppress a result message; yield exit status only.
-test, -t Print which language, input encoding and output encoding will be chosen if the same arguments are gievn to the command, and then quit immediately.
-version, -v
  Print version information and quit.
-help, -h Print help and quit.


idncheck guesses local encoding from locale and environment variables. See the ‘‘LOCAL ENCODING’’ section in idn2.conf(5) for more details.


idncmp(1), idnconv2(1), iconv(3), idn2.conf(5), idnalias.conf(5), idnlang.conf(5)


The automatic input-code selection depends on your system, and sometimes it cannot guess or guess wrong. It is better to explicitly specify it using -in option.
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--> IDNCHECK (1) Sep 21, 2012

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