bug#51311: [PATCH] echo: update --help to document edge cases

[Pádraig Brady]

On 20/10/2021 22:50, Florent Flament wrote:
> * src/echo.c (usage): Document edge cases when displaying arbitrary
> strings with the echo command.
> ---
>   src/echo.c | 8 ++++++++
>   1 file changed, 8 insertions(+)
>
> diff --git a/src/echo.c b/src/echo.c
> index 18513398a..73b44660b 100644
> --- a/src/echo.c
> +++ b/src/echo.c
> @@ -78,6 +78,14 @@ If -e is in effect, the following sequences are 
> recognized:\n\
>     fputs (_("\
>     \\0NNN   byte with octal value NNN (1 to 3 digits)\n\
>     \\xHH    byte with hexadecimal value HH (1 to 2 digits)\n\
> +"), stdout);
> +  fputs (_("\
> +\n\
> +NOTE: The echo command doesn't behave gracefully when displaying\n\
> +arbitrary strings. For example, it can't display the string \"-n\" and\n\
> +requires the STRICTLY_POSIX flag to display \"-e\" or \"-E\". Therefore,\n\
> +if you need to display arbitrary strings please use the printf command\n\
> +instead.\n\
>   "), stdout);
>     printf (USAGE_BUILTIN_WARNING, PROGRAM_NAME);
>     emit_ancillary_info (PROGRAM_NAME);

This is too verbose.
BTW the env var is POSIXLY_CORRECT, not STRICTLY_POSIX.
Anyway I don't think we should mention that in the man page anyway.
I'll push the attached later, which just says printf(1) is preferred.

cheers,
Pádraig

echo-printf.patch
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