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- is allowed in domains

• knome 3y ago
  dash is only allowed in the middle. labels can't start or stop with it. so it wouldn't affect the command arguments. The labels must follow the rules for ARPANET host names. They must start with a letter, end with a letter or digit, and have as interior characters only letters, digits, and hyphen. There are also some restrictions on the length. Labels must be 63 characters or less. https://www.ietf.org/rfc/rfc1035.txt https://www.ietf.org/rfc/rfc1035.txt it's more likely that in the late 90s they just made up their own argument parsing that they liked and the application has just used that ever since.