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.
Unless FreeBSD has been configured to automatically start a graphical environment during startup, the system will boot into a command line login prompt, as seen in this example:
FreeBSD/amd64 (pc3.example.org) (ttyv0) login:
The first line contains some information about the system. The amd64 indicates that the system in this example is running a 64-bit version of FreeBSD. The hostname is pc3.example.org, and ttyv0 indicates that this is the system console.
The second line is the login prompt. The next section describes how to log into FreeBSD at this prompt.
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.
When a FreeBSD system boots, startup scripts are automatically executed in order to prepare the system and to start any services which have been configured to start at system boot. Once the system finishes running its startup scripts, it will present a login prompt:
login:
Type the username that was configured during system installation and press Enter. Then enter the password associated with the username and press Enter. The password is not echoed for security reasons.
Once the correct password is input, the message of the day (MOTD) will be displayed followed by a command prompt (a #, $, or % character). You are now logged into the FreeBSD console and ready to try the available commands.
FreeBSD can be configured to provide many virtual consoles for inputting commands. Each virtual console has its own login prompt and output channel, and FreeBSD takes care of properly redirecting keyboard input and monitor output as you switch between virtual consoles.
Special key combinations have been reserved by FreeBSD for switching consoles.[1]. Use Alt-F1, Alt-F2, through Alt-F8 to switch to a different virtual console in FreeBSD.
When 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 can be used to type commands for FreeBSD to run. The programs that are launched in one virtual console do not stop running when that console is not visible because the user has switched to a different virtual console.
By default, FreeBSD is configured to start eight virtual consoles. The configuration can be customized to start more or fewer virtual consoles. To change the number of and the settings of the virtual consoles, edit /etc/ttys.
Each uncommented line in /etc/ttys (lines that do not start with a # character) contains settings for a single terminal or virtual console. The default version 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 the available options for the virtual consoles, refer to ttys(5).
A detailed description of “single user mode” can be found here. There is only one console when FreeBSD is in single user mode as no other virtual consoles are available in this mode. The settings for single user mode are found in this section of /etc/ttys:
# 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, editing secure to insecure will prompt for the root password when booting into single user mode. The default setting enters single user mode without prompting for a password.
Be careful when changing this setting to insecure. If you ever forget the root password, booting into single user mode is still possible, but may be difficult for someone who is not comfortable with the FreeBSD booting process.
The FreeBSD console default video mode may be adjusted to 1024x768, 1280x1024, or any other size supported by the graphics chip and monitor. To use a different video mode load the VESA module:
# kldload vesa
To determine which video modes are supported by the hardware, use vidcontrol(1). To get a list of supported video modes issue the following:
# vidcontrol -i mode
The output of this command lists the video modes that are supported by the hardware. To select a new video mode, specify the mode using vidcontrol(1) as the root user:
# vidcontrol MODE_279
If the new video mode is acceptable, it can be permanently set on boot by adding it to /etc/rc.conf:
allscreens_flags="MODE_279"
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Refer to syscons(4), atkbd(4), vidcontrol(1) and kbdcontrol(1) for a more technical description of the FreeBSD console and its keyboard drivers. |