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IDN2(1) User Commands IDN2(1)


idn2 - Libidn2 Internationalized Domain Names conversion tool


idn2 [OPTION]... [STRINGS]...


The idn2 tool converts DNS domains from UTF-8 to ASCII compatible encoding (ACE) form, as used in the DNS protocol. The encoding format is the Internationalized Domain Name (IDNA2008/TR46) format.

Internationalized Domain Name (IDNA2008) convert STRINGS, or standard input.

Command line interface to the Libidn2 implementation of IDNA2008.

All strings are expected to be encoded in the locale charset.

To process a string that starts with `-', for example `-foo', use `--' to signal the end of parameters, as in `idn2 --quiet -- -foo'.

Mandatory arguments to long options are mandatory for short options too.

-h, --help
Print help and exit
-V, --version
Print version and exit
-d, --decode
Decode (punycode) domain name
-l, --lookup
Lookup domain name (default)
-r, --register
Register label
-T, --tr46t
Enable TR46 transitional processing
-N, --tr46nt
Enable TR46 non-transitional processing
Disable TR46 processing
Enable STD3 ASCII rules
Disable A-label roundtrip for lookups
Print debugging information
Silent operation


Written by Simon Josefsson, Tim Ruehsen.


Report bugs to:

Report Debian bugs to:
Libidn2 home page: <>
General help using GNU software: <>

Packaged by Debian (2.3.2-1)
Copyright © 2011-2021 Simon Josefsson, Tim Ruehsen.
License GPLv3+: GNU GPL version 3 or later <>.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.



The full documentation for idn2 is maintained as a Texinfo manual. If the info and idn2 programs are properly installed at your site, the command

info idn2

should give you access to the complete manual.

July 2021 Libidn2 2.3.2