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1. UNIX for Dummies Questions & Answers
Hi ,
I have searched wiki for pseudo tty devices but it was very complex for me to understand.
Can any one help me understanding concept behind pseudo-tty in layman language?
According to security manual of our org /etc/securetty files shouldn't have any pseudo tty devices.
i understand
ttyX... (5 Replies)
Discussion started by: pinga123
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LEARN ABOUT LINUX
console
CONSOLE(4) Linux Programmer's Manual CONSOLE(4)
NAME
console - console terminal and virtual consoles
DESCRIPTION
A Linux system has up to 63 virtual consoles (character devices with major number 4 and minor number 1 to 63), usually called /dev/ttyn
with 1 <= n <= 63. The current console is also addressed by /dev/console or /dev/tty0, the character device with major number 4 and minor
number 0. The device files /dev/* are usually created using the script MAKEDEV, or using mknod(1), usually with mode 0622 and owner
root.tty.
Before kernel version 1.1.54 the number of virtual consoles was compiled into the kernel (in tty.h: #define NR_CONSOLES 8) and could be
changed by editing and recompiling. Since version 1.1.54 virtual consoles are created on the fly, as soon as they are needed.
Common ways to start a process on a console are: (a) tell init(1) (in inittab(5)) to start a mingetty(8) (or agetty(8)) on the console; (b)
ask openvt(1) to start a process on the console; (c) start X--it will find the first unused console, and display its output there. (There
is also the ancient doshell(8).)
Common ways to switch consoles are: (a) use Alt+Fn or Ctrl+Alt+Fn to switch to console n; AltGr+Fn might bring you to console n+12 [here
Alt and AltGr refer to the left and right Alt keys, respectively]; (b) use Alt+RightArrow or Alt+LeftArrow to cycle through the presently
allocated consoles; (c) use the program chvt(1). (The key mapping is user settable, see loadkeys(1); the above mentioned key combinations
are according to the default settings.)
The command deallocvt(1) (formerly disalloc) will free the memory taken by the screen buffers for consoles that no longer have any associ-
ated process.
Properties
Consoles carry a lot of state. I hope to document that some other time. The most important fact is that the consoles simulate vt100 ter-
minals. In particular, a console is reset to the initial state by printing the two characters ESC c. All escape sequences can be found in
console_codes(4).
FILES
/dev/console
/dev/tty*
SEE ALSO
chvt(1), deallocvt(1), init(1), loadkeys(1), mknod(1), openvt(1), console_codes(4), console_ioctl(4), tty(4), ttyS(4), charsets(7),
agetty(8), mapscrn(8), mingetty(8), resizecons(8), setfont(8)
Linux 1994-10-31 CONSOLE(4)
