Remount

Remount is the operation of reattaching a filesystem that is already mounted with a different set of options, without unmounting the filesystem or attaching a new device. In Unix-like operating systems, the remount capability is provided by the mount system call and is commonly exposed through the mount command as -o remount. The primary purpose is to apply changes to an active mount, such as switching from read-only to read-write, or enabling or disabling options such as noexec, nosuid, or nodev, without disrupting services that rely on the mount.

Remounts may require elevated privileges (typically root or equivalent capabilities) and will usually fail if the filesystem is busy, if the requested options are incompatible with the filesystem, or if the kernel does not support changing that particular option for the mounted type. Some changes take effect immediately; others may require the filesystem to be unmounted and remounted or the system to be rebooted.

In practice, remount is a maintenance tool used during system administration, for example to apply security-related options after boot, to enable or disable write access for maintenance, or to accommodate changes in fstab entries without downtime. While commonly associated with Linux, remount semantics exist in various forms on other Unix-like systems, though syntax and capabilities may differ.