The mtab (contraction of mounted file systems table) file is a system information file, commonly found on Unix-like systems. This file lists all currently mounted filesystems along with their initialization options. mtab has a lot in common with fstab, the main distinction being that the latter lists all available filesystems whereas the former lists only currently mounted ones. Therefore mtab is usually in a format similar to that of fstab. Most of the time it is possible to directly use lines from mtab in fstab.[1][2]
The file commonly resides in /etc/mtab.
Sample mtab contents:
/dev/sdb1 / ext3 rw,relatime,errors=remount-ro 0 0 proc /proc proc rw,noexec,nosuid,nodev 0 0 /sys /sys sysfs rw,noexec,nosuid,nodev 0 0 varrun /var/run tmpfs rw,noexec,nosuid,nodev,mode=0755 0 0 varlock /var/lock tmpfs rw,noexec,nosuid,nodev,mode=1777 0 0 udev /dev tmpfs rw,mode=0755 0 0 devshm /dev/shm tmpfs rw 0 0 devpts /dev/pts devpts rw,gid=5,mode=620 0 0 lrm /lib/modules/2.6.24-16-generic/volatile tmpfs rw 0 0 securityfs /sys/kernel/security securityfs rw 0 0 gvfs-fuse-daemon /home/alice/.gvfs fuse.gvfs-fuse-daemon rw,nosuid,nodev,user=alice 0 0