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- So you can manually mount a file system

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using the mount command, as we have seen.

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But if you manually mount a file system,

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it's not persistent.

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So your reboot, it's gone.

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And that is why you want
to make them persistent.

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And still, the default way
to go is through /etc/fstab.

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While booting, the /etc/fstab is processed

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to persistently mount these file systems.

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But on modern Linux distributions,

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/etc/fstab is processed by systemd,

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and systemd converts the
mount in a systemd mount.

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If during the boot procedure,

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a file system specified in /etc/fstab

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doesn't mount successfully,

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typically a troubleshooting
prompt is shown

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where the error must be fixed
manually before you can go on.

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In /etc/fstab there are different fields.

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The first field is
mandatory, what to mount.

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That is where you put your device.

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Then where to mount,

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that's a direction where
you are going to mount it.

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The filesystem type is going
to be your EXT4, your XFS,

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or whatever file system it
is that you want to use.

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These three options are
the most important ones.

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Because mount options are
only used in specific cases,

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you might just have defaults
for default mount options,

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nothing specific.

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And the dump option and Fsck option,

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these are kind of legacy,

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just put them to zero,
and that will always work.

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Now let's create some
persistent mounts in /etc/fstab.

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Alright, let me edit /etc/fstab.

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And in /etc/fstab,

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I'm going to include dev/sdb1.

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And this dev/sdb1, I want to mount it on,

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let's say mydata.

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So this was the EXT4 file system,

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and I'm using defaults amount
option in zero and zero,

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and then we are good.

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So I need to make sure
that my data exists,

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and then I'm going to reboot,

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and we are going to check
if this all works out well.

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Now if the boot procedure
is taking a while,

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I suggest you press the escape key

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so that you can see what is going on.

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I can see that it is mounting boot,

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it has just mounted boot,

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00:02:22,710 --> 00:02:25,863
and now it looks as if
it is getting stuck.

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Let's see what's happening.

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00:02:28,950 --> 00:02:29,820
Now, there we go.

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This is what's happening.

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You see what's wrong on the bottom line.

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A start job is running for /dev/sdvb1.

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Well, I can tell you, I
don't have any devices sdvb1.

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So this is systemd.

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Systemd is giving a timeout
on anything that is failing,

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and its default timeout is
one minute and 30 seconds,

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and we just need to wait.

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There's nothing that you
can do to speed it up.

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So now you can see that it has failed,

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and it is continuing,

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and, well, it is entering emergency mode.

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That is because there's
an error in /etc/fstab,

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and the systemd cannot see

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if the error is in a file system,

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or if it's just a typo, or anything.

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So we need human intervention here.

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I'm entering the root password,

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00:03:21,150 --> 00:03:24,060
and, well, after entering
the root password,

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I'm in emergency mode.

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Well, we already know what's going on.

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Lsblk is listing the block devices.

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We need sdb1,

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and we have sdvb1.

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That's an easy fix.

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And in many cases where you see problems

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that relate to /etc/fstab,
it's an easy fix.

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You can use control D to get out of there,

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and then the default
target will be started,

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and everything should be booted all right.

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(keys clicking)

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So now we are back in the root cell,

84
00:04:07,350 --> 00:04:10,500
and I want to verify that
everything worked out alright.

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00:04:10,500 --> 00:04:13,440
Of course you can type the mount command,

86
00:04:13,440 --> 00:04:16,590
but the mount command is
a little bit hard to read.

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00:04:16,590 --> 00:04:20,670
Personally I like lsblk,
list block devices,

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where we can see that sdb1

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is mounted on the partition mydata.

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This is a pretty clean overview
of what is mounted where.

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Now, one advice.

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If you just modified your /etc/fstab,

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00:04:36,540 --> 00:04:38,580
please just use mount -a.

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00:04:38,580 --> 00:04:42,780
Mount -a is going to
try to mount everything

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00:04:42,780 --> 00:04:44,040
that is not yet mounted.

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And if you made any error,
mount -a will tell you.

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00:04:47,580 --> 00:04:50,253
Otherwise, just findmnt.

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00:04:51,150 --> 00:04:53,220
Findmnt is showing you
all the mount points

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00:04:53,220 --> 00:04:56,490
and the devices that are associated to it.

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And findmnt --verify

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00:05:00,060 --> 00:05:03,510
is what you can use to verify the syntax

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00:05:03,510 --> 00:05:05,340
of your /etc/fstab.

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So use either one of these solutions

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to avoid getting into a situation

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where you need to do troubleshooting.