FreeBSD can be used in various ways. One of them is typing commands to a text terminal. A lot of the flexibility and power of a UNIX® operating system is readily available at your hands when using FreeBSD this way. This section describes what “terminals” and “consoles” are, and how you can use them in FreeBSD.
If you have not configured FreeBSD to automatically start a graphical environment during startup, the system will present you with a login prompt after it boots, right after the startup scripts finish running. You will see something similar to:
Additional ABI support:. Local package initialization:. Additional TCP options:. Fri Sep 20 13:01:06 EEST 2002 FreeBSD/i386 (pc3.example.org) (ttyv0) login:
The messages might be a bit different on your system, but you will see something similar. The last two lines are what we are interested in right now. The second last line reads:
FreeBSD/i386 (pc3.example.org) (ttyv0)
This line contains some bits of information about the system you have just booted. You are looking at a “FreeBSD” console, running on an Intel or compatible processor of the x86 architecture[1]. The name of this machine (every UNIX machine has a name) is pc3.example.org, and you are now looking at its system console--the ttyv0 terminal.
Finally, the last line is always:
login:
This is the part where you are supposed to type in your “username” to log into FreeBSD. The next section describes how you can do this.
FreeBSD is a multiuser, multiprocessing system. This is the formal description that is usually given to a system that can be used by many different people, who simultaneously run a lot of programs on a single machine.
Every multiuser system needs some way to distinguish one “user” from the rest. In FreeBSD (and all the UNIX-like operating systems), this is accomplished by requiring that every user must “log into” the system before being able to run programs. Every user has a unique name (the “username”) and a personal, secret key (the “password”). FreeBSD will ask for these two before allowing a user to run any programs.
Right after FreeBSD boots and finishes running its startup scripts[2], it will present you with a prompt and ask for a valid username:
login:
For the sake of this example, let us assume that your username is john. Type john at this prompt and press Enter. You should then be presented with a prompt to enter a “password”:
login: john Password:
Type in john's password now, and press Enter. The password is not echoed! You need not worry about this right now. Suffice it to say that it is done for security reasons.
If you have typed your password correctly, you should by now be logged into FreeBSD and ready to try out all the available commands.
You should see the MOTD or message of the day followed by a command prompt (a #, $, or % character). This indicates you have successfully logged into FreeBSD.
Running UNIX commands in one console is fine, but FreeBSD can run many programs at once. Having one console where commands can be typed would be a bit of a waste when an operating system like FreeBSD can run dozens of programs at the same time. This is where “virtual consoles” can be very helpful.
FreeBSD can be configured to present you with many different virtual consoles. You can switch from one of them to any other virtual console by pressing a couple of keys on your keyboard. Each console has its own different output channel, and FreeBSD takes care of properly redirecting keyboard input and monitor output as you switch from one virtual console to the next.
Special key combinations have been reserved by FreeBSD for switching consoles[3]. You can use Alt-F1, Alt-F2, through Alt-F8 to switch to a different virtual console in FreeBSD.
As you are switching from one console to the next, FreeBSD takes care of saving and restoring the screen output. The result is an “illusion” of having multiple “virtual” screens and keyboards that you can use to type commands for FreeBSD to run. The programs that you launch on one virtual console do not stop running when that console is not visible. They continue running when you have switched to a different virtual console.
The default configuration of FreeBSD will start up with eight virtual consoles. This is not a hardwired setting though, and you can easily customize your installation to boot with more or fewer virtual consoles. The number and settings of the virtual consoles are configured in the /etc/ttys file.
You can use the /etc/ttys file to configure the virtual consoles of FreeBSD. Each uncommented line in this file (lines that do not start with a # character) contains settings for a single terminal or virtual console. The default version of this file that ships with FreeBSD configures nine virtual consoles, and enables eight of them. They are the lines that start with ttyv:
# name getty type status comments # ttyv0 "/usr/libexec/getty Pc" cons25 on secure # Virtual terminals ttyv1 "/usr/libexec/getty Pc" cons25 on secure ttyv2 "/usr/libexec/getty Pc" cons25 on secure ttyv3 "/usr/libexec/getty Pc" cons25 on secure ttyv4 "/usr/libexec/getty Pc" cons25 on secure ttyv5 "/usr/libexec/getty Pc" cons25 on secure ttyv6 "/usr/libexec/getty Pc" cons25 on secure ttyv7 "/usr/libexec/getty Pc" cons25 on secure ttyv8 "/usr/X11R6/bin/xdm -nodaemon" xterm off secure
For a detailed description of every column in this file and all the options you can use to set things up for the virtual consoles, consult the ttys(5) manual page.
A detailed description of what “single user mode” is can be found in Section 12.6.2. It is worth noting that there is only one console when you are running FreeBSD in single user mode. There are no virtual consoles available. The settings of the single user mode console can also be found in the /etc/ttys file. Look for the line that starts with console:
# name getty type status comments # # If console is marked "insecure", then init will ask for the root password # when going to single-user mode. console none unknown off secure
Note: As the comments above the console line indicate, you can edit this line and change secure to insecure. If you do that, when FreeBSD boots into single user mode, it will still ask for the root password.
Be careful when changing this to insecure. If you ever forget the root password, booting into single user mode is a bit involved. It is still possible, but it might be a bit hard for someone who is not very comfortable with the FreeBSD booting process and the programs involved.
The FreeBSD console default video mode may be adjusted to 1024x768, 1280x1024, or any other size supported by your graphics chip and monitor. To use a different video mode, you first must recompile your kernel and include two additional options:
options VESA options SC_PIXEL_MODE
Once the kernel has been recompiled with these two options, you can then determine what video modes are supported by your hardware by using the vidcontrol(1) utility. To get a list of supported video modes issue the following:
# vidcontrol -i mode
The output of this command is a list of video modes that are supported by your hardware. You can then choose to use a new video mode by passing it to vidcontrol(1) in a root console:
# vidcontrol MODE_279
If the new video mode is acceptable, it can be permanently set on boot by setting it in the /etc/rc.conf file:
allscreens_flags="MODE_279"
| [1] |
This is what i386 means. Note that even if you are not running FreeBSD on an Intel 386 CPU, this is going to be i386. It is not the type of your processor, but the processor “architecture” that is shown here. |
| [2] |
Startup scripts are programs that are run automatically by FreeBSD when booting. Their main function is to set things up for everything else to run, and start any services that you have configured to run in the background doing useful things. |
| [3] |
A fairly technical and accurate description of all the details of the FreeBSD console and keyboard drivers can be found in the manual pages of syscons(4), atkbd(4), vidcontrol(1) and kbdcontrol(1). We will not expand on the details here, but the interested reader can always consult the manual pages for a more detailed and thorough explanation of how things work. |