refp

  zsh% echo "hello world" > data
  
  zsh% < data && echo "READABLE"   # <- will print the contents of data
  hello world
  READABLE
  
  zsh% : < data && echo "READABLE" # <- this will not
  READABLE

    % cat subshell.sh
    #!/bin/bash --posix
    ( : < missing.json ); echo AFTER    # <- will echo AFTER
    
    % ./subshell.sh
    ./subshell.sh: line 2: missing.json: No such file or directory
    AFTER
    
    % cat no-subshell.sh
    #!/bin/bash --posix
    : < missing.json; echo AFTER        # <- this will not
    
    % ./no-subshell.sh
    ./no-subshell.sh: line 2: missing.json: No such file or directory

    % : ^- apparently.. there is a difference

    Another approach might be to sit back, have a nice cup
    of zen, and just always pull all updates and then
    update your entire fleet of systems on a weekly basis,
    which, yes, I sure would like to be able to do, but
    reality keeps getting in my way.

    I'm not sure what to do here going forward.

    -Jan

    while true; do apt-get update && apt-get upgrade -y; sleep 1d; done