What does the command mount a do?
A.
It mounts the floppy disk for all users
B.
It shows all mounted file systems
C.
It opens /etc/fstab to edit
D.
It mounts all file systems listed in /etc/fstab
Explanation:
From the man pages:
-a, –all Mount all filesystems (of the given types) mentioned in fstab.
A dash needs to be added to the -a flag in the question to make this more accurate.
The command
mount -a [-t type] [-O optlist]
(usually given in a bootscript) causes all filesystems men-
tioned in fstab (of the proper type and/or having or not hav-
ing the proper options) to be mounted as indicated, except for
those whose line contains the noauto keyword. Adding the -F
option will make mount fork, so that the filesystems are
mounted simultaneously.
The Mount command on its own displays the currently mounted file systems like the /etc/mtab. So the answer should be B.