Important concepts and bits
what is mtab?
matb is the currently mounted file system.
what is fstab?
fstab is the to be mounted file system while booting.
difference between mtab and fstab?
mtab is mounted file system.
fstab is the file system tab to be mounted.
where is the fstab conf and mtab conf
fstab and mtab are located in the etc directory.
etc is located in the / directory.
/ is the top of hierachy in linux.
what are the fstab entries?
there are devices or file system partitions and their types format type mount point like this we have.
example fstab entry config file.
## /etc/fstab
# Created by anaconda on Mon Feb 10 08:32:29 2020
#
# Accessible filesystems, by reference, are maintained under '/dev/disk/'.
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info.
#
# After editing this file, run 'systemctl daemon-reload' to update systemd
# units generated from this file.
#
/dev/mapper/rhel-root / xfs defaults 0 0
UUID=5a3685c4-9e21-40cb-b476-c363a4e9942c /boot xfs defaults 0 0
/dev/mapper/rhel-home /home xfs defaults 0 0
/dev/mapper/rhel-swap swap swap defaults 0 0
/dev/sr0 /mnt iso9660 defaults 0 0
/dev/sdb1 /space ext4 defaults 0 0
how to check last boot time?
boot time when it started the kernel version like this we have other parameters like what users are logged into the system.
example :
[root@balaserver ~]# last
root pts/0 192.168.0.101 Sat Mar 21 18:21 still logged in
root pts/1 192.168.0.110 Fri Mar 20 21:21 - 12:29 (15:08)
root pts/0 192.168.0.102 Fri Mar 20 20:17 - 12:29 (16:12)
root pts/0 192.168.0.102 Thu Mar 19 17:18 - 14:19 (21:00)
reboot system boot 4.18.0-147.el8.x Thu Mar 19 17:16 still running
root pts/0 192.168.0.104 Thu Mar 12 17:24 - 20:39 (03:15)
root pts/2 192.168.0.104 Wed Mar 11 18:44 - 20:59 (02:15)
root pts/1 192.168.0.101 Wed Mar 11 17:10 - crash (8+00:05)
root pts/0 192.168.0.100 Wed Mar 11 16:48 - 18:49 (02:01)
root pts/2 192.168.0.110 Wed Mar 11 16:46 - 16:46 (00:00)
root pts/1 192.168.0.110 Wed Mar 11 16:45 - 16:46 (00:00)
root pts/0 192.168.0.110 Wed Mar 11 16:41 - 16:46 (00:04)
root pts/0 192.168.0.108 Wed Mar 11 16:36 - 16:40 (00:03)
reboot system boot 4.18.0-147.el8.x Wed Mar 11 16:34 still running
reboot system boot 4.18.0-147.el8.x Sun Mar 8 05:54 still running
root pts/1 192.168.0.103 Sat Mar 7 13:29 - 16:34 (03:04)
root tty2 tty2 Sat Mar 7 13:14 - down (03:19)
reboot system boot 4.18.0-147.el8.x Sat Mar 7 12:58 - 16:34 (03:35)
root pts/1 192.168.0.108 Fri Mar 6 01:55 - 08:12 (06:17)
root pts/0 192.168.0.100 Fri Mar 6 01:54 - 08:12 (06:18)
root pts/2 192.168.0.100 Thu Mar 5 19:17 - 19:31 (00:13)
root pts/2 192.168.0.100 Thu Mar 5 19:15 - 19:17 (00:02)
suneel pts/3 192.168.0.100 Thu Mar 5 17:58 - 19:17 (01:19)
root pts/2 192.168.0.100 Thu Mar 5 17:52 - 19:14 (01:21)
root pts/2 192.168.0.100 Thu Mar 5 17:36 - 17:52 (00:15)
root pts/0 192.168.0.105 Thu Mar 5 17:28 - 19:41 (02:12)
root pts/1 192.168.0.105 Thu Mar 5 17:19 - 19:40 (02:21)
root pts/0 192.168.0.105 Thu Mar 5 17:02 - 17:28 (00:25)
reboot system boot 4.18.0-147.el8.x Thu Mar 5 16:56 - 20:09 (1+03:13)
root pts/0 192.168.0.104 Tue Mar 3 19:31 - crash (1+21:24)
reboot system boot 4.18.0-147.el8.x Tue Mar 3 16:08 - 20:09 (3+04:00)
root pts/2 192.168.0.105 Sun Mar 1 22:55 - 23:11 (00:15)
root pts/2 192.168.0.105 Sun Mar 1 21:59 - 22:32 (00:32)
root pts/2 192.168.0.105 Sun Mar 1 15:32 - 18:52 (03:20)
balu pts/1 192.168.0.104 Sat Feb 29 19:34 - crash (2+20:34)
root pts/0 192.168.0.104 Sat Feb 29 19:33 - crash (2+20:35)
reboot system boot 4.18.0-147.el8.x Sat Feb 29 17:15 - 20:09 (6+02:53)
root pts/0 192.168.0.104 Sat Feb 29 16:15 - 17:14 (00:59)
reboot system boot 4.18.0-147.el8.x Sat Feb 29 16:13 - 17:14 (01:00)
root pts/1 192.168.0.104 Sat Feb 29 12:24 - 12:30 (00:06)
root pts/0 192.168.0.104 Sat Feb 29 11:51 - 12:48 (00:57)
root pts/0 192.168.0.104 Sat Feb 29 11:47 - 11:50 (00:03)
root pts/0 192.168.0.104 Sat Feb 29 10:15 - 11:46 (01:31)
reboot system boot 4.18.0-147.el8.x Sat Feb 29 10:14 - 15:50 (05:36)
root pts/0 192.168.0.104 Sat Feb 29 09:53 - 10:07 (00:13)
root pts/0 192.168.0.104 Fri Feb 28 23:53 - 23:56 (00:03)
root pts/3 192.168.0.108 Fri Feb 28 23:06 - 23:14 (00:07)
root pts/0 192.168.0.108 Fri Feb 28 22:01 - 23:14 (01:12)
root pts/3 192.168.0.108 Fri Feb 28 21:44 - 21:57 (00:13)
root pts/2 192.168.0.108 Fri Feb 28 21:42 - 23:14 (01:32)
root pts/1 192.168.0.108 Fri Feb 28 21:37 - 23:14 (01:37)
root pts/0 192.168.0.104 Fri Feb 28 21:26 - 21:56 (00:29)
root pts/1 192.168.0.104 Fri Feb 28 21:25 - 21:26 (00:00)
root pts/1 192.168.0.104 Fri Feb 28 21:23 - 21:25 (00:01)
root pts/0 192.168.0.104 Fri Feb 28 21:20 - 21:26 (00:05)
root pts/0 192.168.0.104 Fri Feb 28 21:14 - 21:20 (00:06)
bala tty2 tty2 Fri Feb 28 21:13 - down (12:53)
reboot system boot 4.18.0-147.el8.x Fri Feb 28 21:03 - 10:07 (13:03)
reboot system boot 4.18.0-147.el8.x Mon Feb 24 16:12 - 19:14 (4+03:01)
root pts/2 192.168.0.108 Mon Feb 24 16:22 - 16:22 (00:00)
root pts/2 192.168.0.105 Mon Feb 24 16:19 - 16:22 (00:02)
root pts/5 192.168.0.105 Mon Feb 24 16:19 - 16:19 (00:00)
root pts/2 192.168.0.105 Mon Feb 24 16:18 - 16:19 (00:00)
root pts/4 192.168.0.105 Mon Feb 24 14:56 - 16:22 (01:26)
root pts/2 192.168.0.105 Mon Feb 24 14:41 - 16:18 (01:36)
root pts/2 192.168.0.105 Mon Feb 24 14:39 - 14:41 (00:01)
root pts/3 192.168.0.109 Mon Feb 24 14:23 - 16:22 (01:59)
root pts/2 192.168.0.105 Mon Feb 24 14:14 - 14:39 (00:25)
root pts/1 192.168.0.105 Mon Feb 24 14:09 - 16:22 (02:13)
root pts/0 192.168.0.105 Mon Feb 24 13:58 - 16:22 (02:24)
root pts/0 192.168.0.100 Sun Feb 23 21:30 - 23:09 (01:38)
root pts/0 192.168.0.100 Sun Feb 23 21:28 - 21:30 (00:02)
root pts/0 192.168.0.100 Sun Feb 23 21:25 - 21:28 (00:02)
root pts/1 192.168.0.100 Sun Feb 23 21:24 - 21:25 (00:00)
root pts/0 192.168.0.100 Sun Feb 23 21:20 - 21:25 (00:04)
root pts/2 192.168.0.100 Sun Feb 23 21:19 - 21:20 (00:00)
root pts/2 192.168.0.100 Sun Feb 23 16:49 - 16:49 (00:00)
root pts/1 192.168.0.100 Sun Feb 23 16:31 - 21:20 (04:49)
root pts/0 192.168.0.100 Sun Feb 23 16:30 - 21:20 (04:50)
reboot system boot 4.18.0-147.el8.x Sun Feb 23 16:22 - 16:23 (1+00:01)
reboot system boot 4.18.0-147.el8.x Sun Feb 23 16:07 - 16:23 (1+00:15)
reboot system boot 4.18.0-147.el8.x Sun Feb 23 16:04 - 16:23 (1+00:18)
reboot system boot 4.18.0-147.el8.x Sun Feb 23 15:43 - 15:44 (00:00)
reboot system boot 4.18.0-147.el8.x Sun Feb 23 15:38 - 15:43 (00:04)
reboot system boot 4.18.0-147.el8.x Sun Feb 23 15:27 - 15:38 (00:11)
reboot system boot 4.18.0-147.el8.x Sun Feb 23 15:22 - 15:38 (00:16)
reboot system boot 4.18.0-147.el8.x Sun Feb 23 15:20 - 15:22 (00:01)
reboot system boot 4.18.0-147.el8.x Sun Feb 23 15:17 - 15:19 (00:02)
reboot system boot 4.18.0-147.el8.x Sun Feb 23 15:16 - 15:16 (00:00)
root pts/2 192.168.0.100 Sun Feb 23 13:41 - crash (01:34)
root pts/1 192.168.0.101 Sun Feb 23 13:13 - crash (02:02)
bala tty2 tty2 Sun Feb 23 12:36 - crash (02:39)
reboot system boot 4.18.0-147.el8.x Sun Feb 23 12:35 - 15:16 (02:41)
bala tty2 tty2 Sun Feb 23 11:38 - down (00:39)
root pts/2 192.168.0.103 Sun Feb 23 11:14 - 12:17 (01:03)
root pts/1 192.168.0.103 Sun Feb 23 11:09 - 12:17 (01:08)
root pts/0 192.168.0.103 Sun Feb 23 08:59 - 12:17 (03:18)
reboot system boot 4.18.0-147.el8.x Sun Feb 23 08:53 - 12:17 (03:24)
root pts/0 192.168.0.103 Sat Feb 22 23:04 - 23:35 (00:30)
root pts/0 192.168.0.103 Sat Feb 22 19:16 - 23:04 (03:47)
root pts/4 192.168.0.103 Sat Feb 22 17:10 - 17:12 (00:01)
root pts/3 192.168.0.108 Sat Feb 22 17:08 - 17:12 (00:03)
root pts/1 192.168.0.108 Sat Feb 22 17:07 - 17:12 (00:04)
root pts/0 192.168.0.103 Sat Feb 22 17:04 - 17:12 (00:08)
root pts/2 192.168.0.103 Sat Feb 22 16:56 - 17:14 (00:17)
root pts/2 192.168.0.103 Sat Feb 22 16:55 - 16:56 (00:00)
root pts/3 192.168.0.103 Sat Feb 22 15:57 - 16:42 (00:44)
root pts/3 192.168.0.103 Sat Feb 22 15:56 - 15:57 (00:00)
bala pts/2 192.168.0.108 Sat Feb 22 15:53 - 16:49 (00:55)
root pts/1 192.168.0.103 Sat Feb 22 15:14 - 17:03 (01:49)
root pts/0 192.168.0.103 Sat Feb 22 15:08 - 17:04 (01:55)
root pts/1 192.168.0.103 Sat Feb 22 13:57 - 14:25 (00:28)
root pts/0 192.168.0.103 Sat Feb 22 13:29 - 14:25 (00:56)
root pts/0 192.168.0.103 Sat Feb 22 12:36 - 13:29 (00:52)
reboot system boot 4.18.0-147.el8.x Sat Feb 22 12:23 - 23:35 (11:11)
root pts/4 192.168.0.103 Sat Feb 22 12:34 - 12:35 (00:01)
root pts/5 192.168.0.103 Sat Feb 22 12:26 - 12:35 (00:08)
root pts/4 192.168.0.103 Sat Feb 22 12:23 - 12:34 (00:10)
root pts/4 192.168.0.103 Sat Feb 22 11:19 - 11:40 (00:21)
root pts/3 192.168.0.103 Sat Feb 22 11:12 - 12:34 (01:21)
root pts/2 192.168.0.103 Sat Feb 22 11:11 - 12:34 (01:23)
root pts/1 192.168.0.107 Sat Feb 22 08:52 - 12:35 (03:42)
bala tty2 tty2 Sat Feb 22 08:45 - down (03:50)
root pts/1 192.168.0.103 Sat Feb 22 00:30 - 00:38 (00:08)
root pts/0 192.168.0.103 Fri Feb 21 23:54 - 02:51 (02:57)
reboot system boot 4.18.0-147.el8.x Fri Feb 21 23:53 - 12:35 (12:42)
root pts/1 192.168.0.103 Fri Feb 21 22:32 - 22:32 (00:00)
root pts/2 192.168.0.103 Wed Feb 19 21:29 - 00:45 (03:16)
root pts/2 192.168.0.103 Wed Feb 19 21:22 - 21:29 (00:06)
root pts/2 192.168.0.103 Wed Feb 19 20:19 - 20:19 (00:00)
root pts/1 192.168.0.103 Wed Feb 19 20:19 - 00:45 (04:26)
root pts/1 192.168.0.103 Wed Feb 19 20:17 - 20:18 (00:00)
root pts/1 192.168.0.103 Wed Feb 19 19:16 - 20:17 (01:01)
root pts/1 192.168.0.103 Wed Feb 19 18:05 - 18:56 (00:51)
root pts/1 192.168.0.103 Wed Feb 19 17:38 - 18:05 (00:26)
root pts/1 192.168.0.103 Wed Feb 19 16:46 - 17:38 (00:51)
root pts/1 192.168.0.103 Wed Feb 19 16:43 - 16:46 (00:03)
root pts/1 192.168.0.103 Wed Feb 19 16:43 - 16:43 (00:00)
root pts/1 192.168.0.103 Wed Feb 19 16:42 - 16:43 (00:00)
root pts/2 192.168.0.103 Wed Feb 19 16:42 - 16:42 (00:00)
root pts/1 192.168.0.103 Wed Feb 19 16:41 - 16:42 (00:01)
root pts/1 192.168.0.108 Wed Feb 19 16:32 - 16:32 (00:00)
bala tty2 tty2 Wed Feb 19 16:30 - down (2+06:02)
reboot system boot 4.18.0-147.el8.x Wed Feb 19 16:28 - 22:32 (2+06:04)
bala tty2 tty2 Wed Feb 12 16:21 - crash (7+00:07)
reboot system boot 4.18.0-147.el8.x Wed Feb 12 16:20 - 22:32 (9+06:12)
root pts/0 192.168.0.105 Mon Feb 10 21:50 - 21:54 (00:03)
root pts/1 fe80::f9dd:87c8: Mon Feb 10 21:29 - 21:40 (00:11)
root pts/0 192.168.0.105 Mon Feb 10 21:28 - 21:40 (00:11)
root pts/2 192.168.0.105 Mon Feb 10 21:27 - 21:27 (00:00)
root pts/1 fe80::f9dd:87c8: Mon Feb 10 21:25 - 21:27 (00:02)
root pts/0 192.168.0.105 Mon Feb 10 21:24 - 21:28 (00:03)
bala tty2 tty2 Mon Feb 10 21:20 - down (00:33)
reboot system boot 4.18.0-147.el8.x Mon Feb 10 21:19 - 21:54 (00:34)
root pts/1 192.168.0.105 Mon Feb 10 20:22 - crash (00:57)
root pts/2 192.168.0.105 Mon Feb 10 20:21 - 20:22 (00:00)
root pts/2 192.168.0.105 Mon Feb 10 20:16 - 20:16 (00:00)
root pts/1 192.168.0.105 Mon Feb 10 20:13 - 20:21 (00:07)
bala tty2 tty2 Mon Feb 10 20:10 - crash (01:09)
reboot system boot 4.18.0-147.el8.x Mon Feb 10 20:09 - 21:54 (01:44)
bala tty2 tty2 Mon Feb 10 20:05 - crash (00:03)
reboot system boot 4.18.0-147.el8.x Mon Feb 10 20:05 - 21:54 (01:49)
bala tty2 tty2 Mon Feb 10 19:59 - down (00:05)
reboot system boot 4.18.0-147.el8.x Mon Feb 10 19:49 - 20:04 (00:15)
wtmp begins Mon Feb 10 19:49:38 2020