IDN(1)

NAME
idn - Internationalized Domain Names command line tool

SYNOPSIS
idn [OPTION]... [STRINGS]...

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

Command line interface to the internationalized domain name library.

All strings are expected to be encoded in the preferred charset used by your locale. Use --debug to find out what this charset is. You can override the charset used by setting environment variable CHARSET.

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

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

-h, --help
    Print help and exit

-V, --version
    Print version and exit

-s, --stringprep
    Prepare string according to nameprep profile

-d, --punycode-decode
    Decode Punycode

-e, --punycode-encode
    Encode Punycode

-a, --idna-to-ascii
    Convert to ACE according to IDNA (default mode)

-u, --idna-to-unicode
    Convert from ACE according to IDNA

--allow-unassigned
    Toggle IDNA AllowUnassigned flag (default off)

--usestd3asciirules
    Toggle IDNA UseSTD3ASCIIRules flag (default off)

--no-tld
    Don't check string for TLD specific rules Only for --idna-to-ascii and --idna-to-unicode

-n, --nfkc
    Normalize string according to Unicode v3.2 NFKC

-p, --profile=STRING
    Use specified stringprep profile instead Valid stringprep profiles: Nameprep iSCSI Nodeprep Resourceprep trace SASLprep

--debug
    Print debugging information

--quiet
    Silent operation

AUTHOR
Written by Simon Josefsson.

REPORTING BUGS
Report bugs to: help-libidn@gnu.org
GNU Libidn home page: <https://www.gnu.org/software/libidn/>
General help using GNU software: <https://www.gnu.org/gethelp/>

COPYRIGHT
Copyright © 2026 Simon Josefsson. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.

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

    info idn

should give you access to the complete manual.