Chapter 6. The second boot

Table of Contents

6.1. dmesg
6.2. Mounting the CD-ROM
6.3. Mounting the floppy
6.4. Accessing a DOS/Windows partition
6.5. Adding users
6.6. Shadow passwords
6.7. Stopping and rebooting the system

During the first boot you have set up a basic system configuration. This chapter describes some common commands and operations.

6.1. dmesg

At system startup the kernel displays a long sequence of messages on the screen: these messages give information about the kernel status (for example, available memory) and the peripherals that have been detected on the system. This information is very important for diagnosing hardware or configuration problems, and for determining the name of the devices for the peripherals (for example you can check if your network card has been detected as ne0 or ne1). Usually these messages scroll on the screen too fast to be useful, but you can use the dmesg(8) command to view them again.

# dmesg | more

If something on your system doesn't appear to work correctly and you ask for help on one of the NetBSD mailing lists, always remember to include the relevant dmesg output in your post: it will help other people diagnose your problem. Note that during the boot process NetBSD also writes a copy of the dmesg output to /var/run/dmesg.out. This feature is useful because the system will scroll “old” messages out of the dmesg buffer over time.

6.2. Mounting the CD-ROM

New users are often surprised by the fact that although the installation program recognized and mounted their CD-ROM perfectly, the installed system seems to have “forgotten” how to use the CD-ROM. There is no special magic for using a CD-ROM: you can mount it as any other file system, all you need to know is the device name and some options to the mount(8) command. You can find the device name with the aforementioned dmesg(8) command. For example, if dmesg(8) displays:

# dmesg | grep ^cd
cd0 at atapibus0 drive 1: <ASUS CD-S400/A, , V2.1H> type 5 cdrom removable

the device name is cd0, and you can mount the CD-ROM with the following commands:

# mkdir /cdrom
# mount -t cd9660 -o ro /dev/cd0a /cdrom

To make things easier, you can add a line to the /etc/fstab file:

/dev/cd0a /cdrom cd9660 ro,noauto 0 0

Without the need to reboot, you can now mount the cdrom with:

# mount /cdrom

When the cdrom is mounted you can't eject it manually; you'll have to unmount it before you can do that:

# umount /cdrom

There is also a software command which unmounts the cdrom and ejects it:

# eject /dev/cd0a

6.3. Mounting the floppy

To mount a floppy you must know the name of the floppy device and the file system type of the floppy. Read the fdc(4) manpage for more information about device naming, as this will differ depending on the exact size and kind of your floppy disk. For example, to read and write a floppy in MS-DOS format you use the following command:

# mount -t msdos /dev/fd0a /mnt

Instead of /mnt, you can use another directory of your choice; you could, for example, create a /floppy directory like you did for the cdrom. If you do a lot of work with MS-DOS floppies, you will want to install the mtools package, which enables you to access a MS-DOS floppy (or hard disk partition) without the need to mount it. It is very handy for quickly copying a file from/to floppy:

# mcopy foo bar a:
# mcopy a:baz.txt baz
# mcopy a:\*.jpg .

6.4. Accessing a DOS/Windows partition

If NetBSD shares the hard disk with MS-DOS or Windows, it is possible modify the disklabel and make the Windows partitions visible from NetBSD. First, you must determine the geometry of the Windows partition, for example using fdisk(8).

# fdisk wd0
NetBSD disklabel disk geometry:
cylinders: 77520, heads: 16, sectors/track: 63 (1008 sectors/cylinder)
Partition table:
0: OS/2 HPFS or NTFS or QNX2 or Advanced UNIX (sysid 7)
    bootmenu: WinXP
    start 63, size 20643462 (10080 MB, Cyls 0-1285), Active
1: NetBSD (sysid 169)
    start 20643525, size 57496635 (28075 MB, Cyls 1285-4864)


This example uses the wd0 hard disk: substitute the device for your hard disk.

The output of the fdisk command shows that the Windows partition uses NTFS (“OS/2 HPFS or NTFS or QNX2 or Advanced UNIX (sysid 7)”), if the partition was FAT it would have said “Primary 'big' DOS, 16-bit FAT (>32MB) (sysid 6)”.

The Windows partition is currently only known in the MBR partition table, in order to mount it from NetBSD it also needs to be in the NetBSD disk's disklabel. There are two ways to do so, editing the disklabel manually using disklabel -e, or using the mbrlabel(8) command, which is what we will describe first.

When running mbrlabel(8), it needs a disk which it will search for partitions that are in the MBR but not in the disklabel, and will then add them to the disklabel:

# disklabel wd0
 d:  78140160         0     unused      0     0        # (Cyl.      0 -  77519)
# mbrlabel -rw wd0
Found NTFS partition; size 20643462 (10079 MB), offset 63
  adding NTFS partition to slot e.
Found 4.2BSD partition; size 57496572 (28074 MB), offset 20643588
  skipping existing unused partition at slot c.

16 partitions:
#        size    offset     fstype [fsize bsize cpg/sgs]
 a:  57236256  20643588     4.2BSD   1024  8192 46920  # (Cyl.  20479*-  77261*)
 b:    260316  77879844       swap                     # (Cyl.  77261*-  77519)
 c:  57496572  20643588     unused      0     0        # (Cyl.  20479*-  77519)
 d:  78140160         0     unused      0     0        # (Cyl.      0 -  77519)
 e:  20643462        63       NTFS                     # (Cyl.      0*-  20479*)

Updating in-core and on-disk disk label.
# disklabel wd0
 d:  78140160         0     unused      0     0        # (Cyl.      0 -  77519)
 e:  20643462        63       NTFS                     # (Cyl.      0*-  20479*) 

If you can't or don't want to use mbrlabel(8) for some reason, you will have to edit the disklabel manually with data from the fdisk-command above. The partition with the NTFS filesystem begins at sector 63 and has a size of 20643462 sectors. The NetBSD partition begins at sector 20643525 (20643525 = 20643462 + 63). You will use this data to modify the BSD disklabel: all you have to do is add one line which defines the position and type of the NTFS partition, choosing one of the still unused partition id letters. Use the disklabel command to modify the disklabel. If you give the -e option to disklabel it will invoke your favourite editor ($EDITOR) to modify the disklabel. For example:

# disklabel -e wd0
#        size   offset     fstype  [fsize bsize  cpg]
 d:  78140160         0     unused      0     0        # (Cyl.      0 -  77519)
 e:  20643462        63       NTFS 

The partitions from “a” to “d” were already used, and the first available id was “e”. The “size” and “offset” fields have been filled with the previously calculated numbers. Next, the mount point must be created. For example:

# mkdir /c

finally, a line will be added to the /etc/fstab file.

/dev/wd0e /c ntfs ro,noauto 1 3

If you want to mount a MS-DOS "FAT" partition instead of a NTFS partition, use MSDOS as the "fstype" in the disklabel and "msdos" as filesystem type (3rd column) in /etc/fstab. You can also mount FAT-filesystems read/write, i.e. you can use "rw" instead of "ro" in /etc/fstab too. For details about NetBSD support for the MSDOS and NTFS filesystems, see mount_msdos(8) and mount_ntfs(8).

Now the Windows partition can be mounted with a simple command:

# mount /c

With this method you can mount NFS, FAT and FAT32 partitions. If you want to mount the partition(s) automatically at startup, remove the noauto option from /etc/fstab.

/dev/wd0e /c ntfs ro 1 3

6.5. Adding users

It's time to add new users to the system, since you don't want to use the root account for your daily work (yes, we're serious about that!). NetBSD offers the useradd(8) utility to create user accounts. For example, to create a new user:

# useradd -m joe

The defaults for the useradd(8) command can be changed; see the useradd(8) man page.

Accounts that can su(1) to root are required to be in the "wheel" group. This can be done when the account is created by specifying a secondary group:

# useradd -m -G wheel joe

As an alternative, the usermod(8) command can be used to add a user to an existing group:

# usermod -G wheel joe


You can edit /etc/group directly to add users to groups, but do not edit /etc/passwd directly! All changes made to that file will get lost, see Section 6.6, “Shadow passwords”.


If the system uses ssh, direct root access via ssh is disabled by default. Check the sshd_config(5) and /etc/ssh/sshd_config to change this behaviour.

6.6. Shadow passwords

Shadow passwords are enabled by default on NetBSD: all the passwords in /etc/passwd contain an “*”; the encrypted passwords are stored in another file, /etc/master.passwd, that can be read only by root. When you start vipw(8) to edit the password file, the program opens a copy of /etc/master.passwd; when you exit, vipw(8) checks the validity of the copy, creates a new /etc/passwd and installs the new /etc/master.passwd file. Finally, vipw(8) launches pwd_mkdb(8), which creates the files /etc/pwd.db and /etc/spwd.db, two databases which are equivalent to /etc/passwd and /etc/master.passwd but faster to process.

As you can see, passwords are handled automatically by NetBSD; if you use vipw(8) to edit the password file you don't need any special administration procedure.

It's very important to always use vipw and the other tools for account administration (chfn(1), chsh(1), chpass(1), passwd(1)) and to never modify directly /etc/master.passwd or /etc/passwd.

6.7. Stopping and rebooting the system

Use one of the following two shutdown(8) commands to halt and/or reboot the system:

# shutdown -h now
# shutdown -r now

Two other commands perform the same tasks are:

# halt
# reboot

halt(8), reboot(8), and shutdown(8) are not synonyms: the latter is more sophisticated. On a multiuser system you should really use shutdown(8); this will allow you to schedule a shutdown time, notify users, and it will also take care to shutdown database processes etc. properly without simply kill(1)ing them. For a more detailed description, see the shutdown(8), halt(8) and reboot(8) manpages.