Home / ubuntu / Questions / 1236657
Accepted
jfhr
Asked: 2020-05-08 08:23:06 +0800 CST

Why should apt-key output not be parsed?

  • 772

To validate that the docker gpg key is installed, I ran:

sudo apt-key fingerprint 0EBFCD88 | grep "9DC8 5822 9FC7 DD38 854A  E2D8 8D81 803C 0EBF CD88"

Which resulted in the following output:

Warning: apt-key output should not be parsed (stdout is not a terminal)
      9DC8 5822 9FC7 DD38 854A  E2D8 8D81 803C 0EBF CD88

I found this Stack Overflow question on how to circumvent the warning, but I couldn't find any sources on why it appears in the first place? What's the reason you shouldn't parse apt-key output?

command-line grep stdout

1 Answers

  1. Best Answer

    From man apt-key:

    DESCRIPTION
   apt-key is used to manage the list of keys used by apt to authenticate
   packages. Packages which have been authenticated using these keys will
   be considered trusted.
   Note that if usage of apt-key is desired the additional installation of
   the GNU Privacy Guard suite (packaged in gnupg) is required. For this
   reason alone the programmatic usage (especially in package maintainer
   scripts!) is strongly discouraged. Further more the output format of all
   commands is undefined and can and does change whenever the underlying
   commands change.  apt-key will try to detect such usage and generates
   warnings on stderr in these cases.
    • 7