Why do some Linux utility programs send output for "normal" operation to STDERR instead of STDOUT?
For example, when I run the following command (in CentOS 7.3):
/usr/sbin/grub2-mkconfig -o /boot/grub2/grub.cfg 1> /dev/null ; echo $?
I see the output on the TTY even though the exit status is zero and there are no errors.
Generating grub configuration file ... Found linux image: /boot/vmlinuz-3.10.0-514.el7.x86_64 Found initrd image: /boot/initramfs-3.10.0-514.el7.x86_64.img Found linux image: /boot/vmlinuz-0-rescue-1ef39414718640fe9f6ec0f6d65fdc3e Found initrd image: /boot/initramfs-0-rescue-1ef39414718640fe9f6ec0f6d65fdc3e.img done 0
I've noticed a handful of other programs that do this as well. Wondering if there is some good explanation.
For reference, I need to call this this line in an RPM %post script and I'd like to redirect "normal" output to
/dev/null and capture only true "error" type messages. This particular command does not offer a
-q quiet switch.