klibc - Dec 2025 - mount: Error message in case of missing -t should identify the cause

Calling klibc's mount utility without specifying the filesystem type

| mount /dev/sdb1 /mnt/

fails with the error message

| Usage: mount [-r] [-w] [-o options] [-t type] [-f] [-i] [-n] device directory

This message is a bit confusing, because that is exactly how I am
calling mount. There is no indication that the program misses the
filesystem type, instead the message seems to confirm that -t is
optional. This stumped me for a while when debugging an initramfs
problem.


I'd suggest ...

... either changing to a multi-variant usage text such as

| Usage:
|   mount [-r] [-w] [-o options] [-f] [-i] [-n] -t type device directory
|   mount -o bind|move|remount[,options] [-r] [-w] [-f] [-i] [-n] device
directory

to indicate when the type is mandatory,


... or splitting the argument check in
https://git.kernel.org/pub/scm/libs/klibc/klibc.git/tree/usr/utils/mount_main.c?id=1d27e1732f1326eaf98f4624100f83232d843616#n151
in the following way:

- not exactly two positional arguments -> show the normal usage message

- two positional arguments, but type is NULL -> show a specific error 
message such as "missing -t type" or "filesystem type required,
except
for -o bind/move/remount"


(Another course of action would be to actually make -t optional and, if 
unspecified, try the non-nodev filesystems from /proc/filesystems until 
one works - like busybox does.? However I understand that this is
probably beyond the scope of klibc's minimalistic design.)

Best regards,
Kristof