On 8/16/20 11:20 AM, Eli Schwartz wrote:
https://pubs.opengroup.org/onlinepubs/9699919799/utilities/echo.html
echo does not accept options, and is not permitted to accept options
including "--".
bash does accept -n, -e, -E in violation of POSIX, unless shopt -s shopt
-s xpg_echo is set, but it doesn't implement -- and I don't really see a
justification to do so.
Not quite: https://www.austingroupbugs.net/view.php?id=1222 says that
accepting -e and -E will become acceptable in the next revision of POSIX
(accepting -n was already acceptable on non-XSI systems).
Either enable xpg_echo or use printf.
POSIX recommends using printf. My personal recommendation is to avoid
xpg_echo except when trying to break things - there are a number of what
claim to be bash scripts that are not aware of the effects of xpg_echo
and which operate incorrectly when you actually set it; whereas using
printf is reliably portable.
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
