如何在 bash 中为 printf 的每一行添加评论？

Question

I have the following code in my Dockerfile . Then I piped the output to my setup.py . I need to run this command in linux terminal. How can i put comment on each line?

  printf "%s\n" \
    # Facebook OAuth Client ID (default)
    "1234" \
    # Facebook OAuth Secret (default)
    "abcd" \
    # Google OAuth Client ID (default)
    "5678" \
    # Google OAuth Secret (default)
    "qwer" \

Answer 1

Using arrays in order to avoid long escaped by \ lists of arguments is a good practice. You can leave a comment for each element.

CREDENTIALS=(
    # Facebook OAuth Client ID (default)
    "1234"
    # Facebook OAuth Secret (default)
    "abcd"
    # Google OAuth Client ID (default)
    "5678"
    # Google OAuth Secret (default)
    "qwer"
)
printf "%s\n" "${CREDENTIALS[@]}"

Answer 2

printf "%s\n" \
    $(: 'Facebook OAuth Client ID (default)') \
    "1234" \
    $(: 'Facebook OAuth Secret (default)') \
    "abcd" \
    $(: 'Google OAuth Client ID (default)') \
    "5678" \
    $(: 'Google OAuth Secret (default)') \
    "qwer"

$(command) is command substitution, it gets replaced with the output of the command.

: is a command that does nothing and produces no output. The argument needs to be quoted because of the (default) , which would otherwise be executed as a command in a subshell.