Filesystem-Independent Mount Options (cont.)

set-group-ID bits or file capabilities when executing programs from this filesystem. nosuid Do not honor set-user-ID and set-group-ID bits or file capabilities when executing programs from this filesystem. In addition, SELinux domain transitions require permission nosuid_transition, which in turn needs also policy capability nnp_nosuid_transition. silent Turn on the silent flag. loud Turn off the silent flag. owner Allow an ordinary user to mount the filesystem if that user is the owner of the device. This option implies the options nosuid and nodev (unless overridden by subsequent options, as in the option line owner,dev,suid). remount Attempt to remount an already-mounted filesystem. This is commonly used to change the mount flags for a filesystem, especially to make a readonly filesystem writable. It does not change device or mount point. The remount operation together with the bind flag has special semantics. See above, the subsection Bind mount operation. The default kernel behavior for VFS mount flags (nodev,nosuid,noexec,ro) is to reset all unspecified flags on remount. That’s why mount(8) tries to keep the current setting according to fstab or /proc/self/mountinfo. This default behavior is possible to change by --options-mode. The recursive change of the mount flags (supported since v2.39 on systems with mount_setattr(2) syscall), for example, mount -o remount,ro=recursive, do not use "reset-unspecified" behavior, and it works as a simple add/remove operation and unspecified flags are not modified. The remount functionality follows the standard way the mount command works with options from fstab. This means that mount does not read fstab (or mtab) only when both device and dir are specified. mount -o remount,rw /dev/foo /dir After this call all old mount options are replaced and arbitrary stuff from fstab (or mtab) is ignored, except the loop= option which is internally generated and maintained by the mount command. mount -o remount,rw /dir After this call, mount reads fstab and merges these options with the options from the command line (-o). If no mountpoint is found in fstab, then it defaults to mount options from /proc/self/mountinfo. mount allows the use of --all to remount all already mounted filesystems which match a specified filter (-O and -t). For example: mount --all -o remount,ro -t vfat remounts all already mounted vfat filesystems in read-only mode. Each of the filesystems is remounted by mount -o remount,ro /dir semantic. This means the mount command reads fstab or mtab and merges these options with the options from the command line. ro Mount the filesystem read-only. rw Mount the filesystem read-write. sync All I/O to the filesystem should be done synchronously. In the case of media with a limited number of write cycles (e.g. some flash drives), sync may cause life-cycle shortening. user Allow an ordinary user to mount the filesystem. The name of the mounting user is written to the mtab file (or to the private libmount file in /run/mount on systems without a regular mtab) so that this same user can unmount the filesystem again. This option implies the options noexec, nosuid, and nodev (unless overridden by subsequent options, as in the option line user,exec,dev,suid). nouser Forbid an ordinary user to mount the

This section continues detailing filesystem-independent mount options for the `mount` command, specifically covering `nosuid`, `silent`, `loud`, `owner`, `remount`, `ro`, `rw`, `sync`, `user`, and `nouser`. These options control privilege escalation via setuid/setgid, toggling silent mode, allowing user-specific mounting, remounting behavior, read-only/read-write status, synchronous I/O, and user mount permissions.