What is a virtual terminal for?
When I press Ctrl + Alt + F1 it goes to virtual terminal. What is this virtual terminal for? When do you need to use it?
This question is prett well covered here: askubuntu.com/questions/14284/… . and you would use it when you don’t have (or need. or want) a Graphical User Interface. it is a text based Command Line Interface (with no graphics at all)
The advantage of it is that it is 99% of the time accessible and usable, even if the system is short of freezing or the graphical interface has frozen or crashed hard.
4 Answers 4
A Virtual Terminal is a full-screen terminal which doesn’t run inside an X window (unlike the terminal window on your graphical desktop). Virtual terminals are found on all GNU/Linux systems, even on systems which don’t have a desktop environment or graphical system installed.
Virtual terminals can be accessed on an Ubuntu system by pressing Ctrl + Alt + F1 till F6 . To come back to the graphical session, press Alt + F7 .
You can get more in-depth info about virtual terminals on its Wikipedia article.
Not all users need or run a graphical environment, and they will work from the virtual terminals.
Many (most) servers do not have a graphical environment as users are rarely logged in to the console. Servers most often require a command line from which the administrator can access the system to monitor or configure it. The virtual terminal provides this environment. Having more than one virtual terminal allows the administrator to switch to another terminal if necessary.
On a desktop with a broken Xserver (graphical environment) the virtual console provides a terminal session from which the Xserver can be reconfigured.
Just to add — Ubuntu Server has just the terminal, no graphical desktop. And one reason you might not need a graphical display is if the host is only accessed via SSH.
The main-frame computers to which old text terminals were connected to were not considered to be «servers». They were just part of the computer system just like a monitor doesn’t connect to a server PC. Virtual terminals are not real text-terminals but are emulated text-terminals. It’s important to include the word «text» since they are not GUI terminals (sometimes called thin Clients).
Virtual terminals are nice since one can set up each one to have a different color display by putting the setterm program in say the /etc/rc-local file that runs at boot time. Then one may use one virtual terminal to run a script that does something that fails; Use another terminal to change the configuration that might fix the problem; Use still another terminal to look up documentation regarding the problem; use another terminal to go on the Internet with a text browser to help solve the problem, etc., etc. Since each screen has a different color background, seeing the right color assures one that they are where they want to be when switching from one terminal to another. But alas, there are not enough colors; only 8. There is a terminal type linux-16color but how to use it? setterm doesn’t support it.
Linux console
The Linux console is a system console internal to the Linux kernel. The Linux console provides a way for the kernel and other processes to send text output to the user, and to receive text input from the user. The user typically enters text with a computer keyboard and reads the output text on a computer monitor. The Linux kernel supports virtual consoles — consoles that are logically separate, but which access the same physical keyboard and display.
This article describes the basics of the Linux console and how to configure the font display. Keyboard configuration is described in the /Keyboard configuration subpage.
Implementation
This article or section needs expansion.
Reason: In what ways is the Linux console limited compared to terminal emulators? (Discuss in Talk:Linux console)
The console, unlike most services that interact directly with users, is implemented in the kernel. This contrasts with terminal emulation software, such as Xterm, which is implemented in user space as a normal application. The console has always been part of released Linux kernels, but has undergone changes in its history, most notably the transition to using the framebuffer and support for Unicode.
Despite many improvements in the console, its full backward compatibility with legacy hardware means it is limited compared to a graphical terminal emulator.
Virtual consoles
The console is presented to the user as a series of virtual consoles. These give the impression that several independent terminals are running concurrently; each virtual console can be logged in with different users, run its own shell and have its own font settings. The virtual consoles each use a device /dev/ttyX , and you can switch between them by pressing Alt+Fx (where x is equal to the virtual console number, beginning with 1). The device /dev/console is automatically mapped to the active virtual console.
Text mode
Since Linux originally began as a kernel for PC hardware, the console was developed using standard IBM CGA/EGA/VGA graphics, which all PCs supported at the time. The graphics operated in VGA text mode, which provides a simple 80×25 character display with 16 colours. This legacy mode is similar to the capabilities of dedicated text terminals, such as the DEC VT100 series. It is still possible to boot in text mode (with vga=0 nomodeset ) if the system hardware supports it, but almost all modern distributions (including Arch Linux) use the framebuffer console instead.
Framebuffer console
As Linux was ported to other non-PC architectures, a better solution was required, since other architectures do not use VGA-compatible graphics adapters, and may not support text modes at all. The framebuffer console was implemented to provide a standard console across all platforms, and so presents the same VGA-style interface regardless of the underlying graphics hardware. As such, the Linux console is not a terminal emulator, but a terminal in its own right. It uses the terminal type linux , and is largely compatible with VT100.
Keyboard shortcuts
| Keyboard Shortcut | Description |
|---|---|
| Ctrl+Alt+Del | Reboots the system (specified by the symlink /usr/lib/systemd/system/ctrl-alt-del.target ) |
| Alt+F1 , F2 , F3 , . | Switch to n-th virtual console |
| Alt+Left | Switch to previous virtual console |
| Alt+Right | Switch to next virtual console |
| Scroll Lock | When Scroll Lock is activated, input/output is locked |
| Ctrl+c | Kills current task |
| Ctrl+d | Inserts an EOF |
| Ctrl+z | Pauses current Task |
Fonts
Note: This section is about the Linux console. For alternative console solutions offering more features (full Unicode fonts, modern graphics adapters etc.), see KMSCON or similar projects.
The Linux console uses UTF-8 encoding by default, but because the standard VGA-compatible framebuffer is used, a console font is limited to either a standard 256, or 512 glyphs. If the font has more than 256 glyphs, the number of colours is reduced from 16 to 8. In order to assign correct symbol to be displayed to the given Unicode value, a special translation map, often called unimap, is needed. Nowadays, most of the console fonts have the unimap built-in; historically, it had to be loaded separately.
By default, the virtual console uses the kernel built-in font with a CP437 character set[1], but this can be easily changed. The kernel offers about 15 built in fonts to choose from, from which the officially supported kernels provide two: VGA 8×16 font ( CONFIG_FONT_8x16 ) and Terminus 16×32 font ( CONFIG_FONT_TER16x32 ). The kernel chooses the one to use based on its evaluation of the screen resolution. Another builtin font can be forced upon by kernel parameters boot parameter setting such as fbcon=font:TER16x32 .
The kbd package provides tools to override the kernel decision for virtual console font and font mapping. Available fonts are provided in the /usr/share/kbd/consolefonts/ directory; those ending with .psfu or .psfu.gz have a Unicode translation map built-in.
Keymaps, the connection between the key pressed and the character used by the computer, are found in the subdirectories of /usr/share/kbd/keymaps/ ; see /Keyboard configuration for details.
Note: Replacing the font can cause issues with programs that expect a standard VGA-style font, such as those using line drawing graphics.
Tip: For European based languages written in Latin/Greek letters, you can use the eurlatgr font. It includes a broad range of Latin/Greek letter variations as well as special characters [2].
Preview and temporary changes
shows a table of glyphs or letters of a font.
setfont temporarily change the font if passed a font name (in /usr/share/kbd/consolefonts/ ) such as
Font names are case-sensitive. With no parameter, setfont returns the console to the default font.
So to have a small 8×8 font, with that font installed like seen below, use e.g.:
$ setfont -h8 /usr/share/kbd/consolefonts/drdos8x8.psfu.gz
To have a bigger font, the Terminus font ( terminus-font ) is available in many sizes, such as ter-132b which is large.
Note: setfont only works on the console currently being used. Any other consoles, active or inactive, remain unaffected.
Persistent configuration
The FONT variable in /etc/vconsole.conf is used to set the font at boot, persistently for all consoles. See vconsole.conf(5) for details.
For displaying characters such as Č, ž, đ, š or Ł, ę, ą, ś using the font lat2-16.psfu.gz :
It means that second part of ISO/IEC 8859 characters are used with size 16. You can change font size using other values (e.g. lat2-08 ). For the regions determined by 8859 specification, look at the Wikipedia:ISO/IEC 8859#The parts of ISO/IEC 8859.
Since mkinitcpio v33, the font specified in /etc/vconsole.conf gets automatically loaded during early userspace by default via the consolefont hook, which adds the font to the initramfs. See Mkinitcpio#HOOKS for more information.
You may also need to restart systemd-vconsole-setup.service after changing /etc/vconsole.conf .
If the fonts appear to not change on boot, or change only temporarily, it is most likely that they got reset when graphics driver was initialized and console was switched to framebuffer. By default, all in-tree kernel drivers are loaded early, NVIDIA users should see NVIDIA#Early loading to load their graphics driver before /etc/vconsole.conf is applied.