idn2 - Man Page

Libidn2 Internationalized Domain Names conversion tool


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


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.

All input 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

Prints help and exits.

-V,  --version

Prints version and exits.

-d,  --decode

Decode an ACE name according to IDNA2008.

-l,  --lookup

Encode to ACE according to IDNA2008 (the default).

-r,  --register

Registers a label.

-T,  --tr46t

Enable TR#46 transitional processing.

-N,  --tr46nt

Enable TR#46 non-transitional processing (default).


Disable TR#46 processing.


Enable STD3 ASCII rules.


Prints debugging information.


Silent operation.


Written by Simon Josefsson.

Reporting bugs

Report bugs to the gitlab issue tracker of the project


May 2019