How to detach-sign a file with a specific private key? || Why this fails?

Question

I have a .tar.xz file which I would like to detach-sign using my gpg private key.

The problem is, I have multiple of private keys imported to my keyring and need to choose, which one to use.

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Progress

This I am trying to execute:

gpg --output somefile.tar.xz.sig --detach-sig somefile.tar.xz --local-user [fingerprint]

but I get an error:

gpg: Note: '--local-user' is not considered an option
gpg: can't open '--local-user': No such file or directory
gpg: signing failed: No such file or directory

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What am I doing wrong here and how do I fix it?

Answer 1

Solution

I have been to remedy the situation using the following working example:

gpg --local-user [fingerprint] --sign --armor --output somefile.tar.xz.asc --detach-sig somefile.tar.xz

Parsing

• gpg: the program doing the signing; in my case version 2.2.4

• --local-user: takes an ID as an argument or a fingerprint in my case.

• --sign: action for gpg to do.

• --armor: outputs human-readable characters instead of binary.

• --output: takes a non-existing file name as an argument, this is to be the result of gpg's work. In case it exists, it will ask you if you wish to overwrite.

• --detach-sig: instructs gpg not to sign the file directly and create a separate signature file.

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Non-working examples

1. If you put the --local-user and its argument on the end, instead of the beginning, you will get the error as is in my question:

   gpg --sign --armor --output somefile.tar.xz.asc --detach-sig somefile.tar.xz --local-user [fingerprint]
   

   So, the --local-user and its argument shall come first (if possible).

2. If you reverse the --output and --detach-sig, you will get an error similar to what is my question:

   gpg --local-user [fingerprint] --sign --armor --detach-sig somefile.tar.xz --output somefile.tar.xz.asc
   

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Conclusion

The order of given arguments matters. That is why it failed.