/usr/bin/idn

Usage: /usr/bin/idn [OPTION]... [STRINGS]...
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

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/>