From owner-svn-doc-head@FreeBSD.ORG Wed Feb 27 20:38:17 2013 Return-Path: Delivered-To: svn-doc-head@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by hub.freebsd.org (Postfix) with ESMTP id C9DC4C4E; Wed, 27 Feb 2013 20:38:17 +0000 (UTC) (envelope-from dru@FreeBSD.org) Received: from svn.freebsd.org (svn.freebsd.org [IPv6:2001:1900:2254:2068::e6a:0]) by mx1.freebsd.org (Postfix) with ESMTP id BABEFDCF; Wed, 27 Feb 2013 20:38:17 +0000 (UTC) Received: from svn.freebsd.org ([127.0.1.70]) by svn.freebsd.org (8.14.5/8.14.5) with ESMTP id r1RKcHt2095380; Wed, 27 Feb 2013 20:38:17 GMT (envelope-from dru@svn.freebsd.org) Received: (from dru@localhost) by svn.freebsd.org (8.14.5/8.14.5/Submit) id r1RKcHQb095379; Wed, 27 Feb 2013 20:38:17 GMT (envelope-from dru@svn.freebsd.org) Message-Id: <201302272038.r1RKcHQb095379@svn.freebsd.org> From: Dru Lavigne Date: Wed, 27 Feb 2013 20:38:17 +0000 (UTC) To: doc-committers@freebsd.org, svn-doc-all@freebsd.org, svn-doc-head@freebsd.org Subject: svn commit: r41052 - head/en_US.ISO8859-1/books/handbook/serialcomms X-SVN-Group: doc-head MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-doc-head@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: SVN commit messages for the doc tree for head List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 27 Feb 2013 20:38:17 -0000 Author: dru Date: Wed Feb 27 20:38:17 2013 New Revision: 41052 URL: http://svnweb.freebsd.org/changeset/doc/41052 Log: First pass at this chapter. This patch addresses the following: - &os;, you, and please - fix xref, acronym, and directory tags (still needs ulink review) - removed redundant warning, leaving only first instance; this warning can be removed altogether once 7.x is EOL at end of month Approved by: bcr (mentor) Modified: head/en_US.ISO8859-1/books/handbook/serialcomms/chapter.xml Modified: head/en_US.ISO8859-1/books/handbook/serialcomms/chapter.xml ============================================================================== --- head/en_US.ISO8859-1/books/handbook/serialcomms/chapter.xml Tue Feb 26 16:52:43 2013 (r41051) +++ head/en_US.ISO8859-1/books/handbook/serialcomms/chapter.xml Wed Feb 27 20:38:17 2013 (r41052) @@ -13,31 +13,28 @@ serial communications - &unix; has always had support for serial communications. In - fact, the very first &unix; machines relied on serial lines for - user input and output. Things have changed a lot from the days - when the average terminal consisted of a - 10-character-per-second serial printer and a keyboard. This - chapter will cover some of the ways in which FreeBSD uses serial - communications. + &unix; has always had support for serial communications as + the very first &unix; machines relied on serial lines for user + input and output. Things have changed a lot from the days + when the average terminal consisted of a 10-character-per-second + serial printer and a keyboard. This chapter covers some of the + ways serial communications can be used on &os;. After reading this chapter, you will know: - How to connect terminals to your FreeBSD - system. + How to connect terminals to a &os; system. - How to use a modem to dial out to remote - hosts. + How to use a modem to dial out to remote hosts. - How to allow remote users to login to your - system with a modem. + How to allow remote users to login to a &os; system + with a modem. - How to boot your system from a serial console. + How to boot a &os; system from a serial console. @@ -45,17 +42,16 @@ - Know how to configure and install a new kernel (). + Know how to configure and + install a custom kernel. - Understand &unix; permissions and processes (). + Understand &os; permissions + and processes. Have access to the technical manual for the serial - hardware (modem or multi-port card) that you would like to - use with FreeBSD. + hardware to be used with &os;. @@ -82,30 +78,30 @@ bits-per-second - bps + bps - Bits per Second — the rate at which data is - transmitted + Bits per Second (bps) is the rate + at which data is transmitted. - DTE + DTE DTE - Data Terminal Equipment — for example, your - computer + An example of a Data Terminal Equipment + (DTE) is a computer. - DCE + DCE DCE - Data Communications Equipment — your - modem + An example of a Data Communications Equipment + (DTE) is a modem. @@ -115,8 +111,9 @@ RS-232C cables - EIA standard for hardware serial - communications + The original standard for hardware serial + communications. It is now usually referred to as + TIA-232 @@ -124,28 +121,26 @@ When talking about communications data rates, this section does not use the term baud. Baud refers to the number of electrical state transitions that may be made in a - period of time, while bps (bits per second) is - the correct term to use (at least it does - not seem to bother the curmudgeons quite as much). + period of time, while bps is the + correct term to use. Cables and Ports - To connect a modem or terminal to your FreeBSD system, you - will need a serial port on your computer and the proper cable - to connect to your serial device. If you are already familiar - with your hardware and the cable it requires, you can safely - skip this section. + To connect a modem or serial terminal to a &os; system, a + serial port on the computer and the proper cable to connect to + the serial device are needed. Users who are already familiar + with serial hardware and cabling can safely skip this + section. Cables There are several different kinds of serial cables. The - two most common types for our purposes are null-modem cables - and standard (straight) RS-232 cables. The - documentation for your hardware should describe the type of - cable required. + two most common types are null-modem cables and standard + RS-232 cables. The documentation for the hardware should + describe the type of cable required. Null-modem Cables @@ -160,16 +155,15 @@ Transmitted Data pin on one end goes to the Received Data pin on the other end. - You can also construct your own null-modem cable for - use with terminals (e.g., for quality purposes). This - table shows the RS-232C signals - and the pin numbers on a DB-25 connector. Note that the - standard also calls for a straight-through pin 1 to pin 1 - Protective Ground line, but it is - often omitted. Some terminals work OK using only pins 2, - 3 and 7, while others require different configurations - than the examples shown below. + A null-modem cable can be constructed for use with + terminals. The following table shows the RS-232C signal names + and the pin numbers on a DB-25 connector. While the + standard calls for a straight-through pin 1 to pin 1 + Protective Ground line, it is often + omitted. Some terminals work using only pins 2, 3, and + 7, while others require different configurations than + the examples shown below. DB-25 to DB-25 Null-Modem Cable @@ -261,8 +255,8 @@
- Here are two other schemes more common - nowadays. + The next two tables show two other common + schemes. DB-9 to DB-9 Null-Modem Cable @@ -451,10 +445,9 @@ and a long wire to the other single pin. - The above designs seems to be the most popular. In - another variation (explained in the book RS-232 - Made Easy) SG connects to SG, TD connects to - RD, RTS and CTS connect to DCD, DTR connects to DSR, and + The above designs seem to be the most popular. In + another variation, SG connects to SG, TD connects to RD, + RTS and CTS connect to DCD, DTR connects to DSR, and vice-versa. @@ -464,11 +457,11 @@ RS-232C cables A standard serial cable passes all of the RS-232C - signals straight through. That is, the Transmitted + signals straight through. The Transmitted Data pin on one end of the cable goes to the Transmitted Data pin on the other end. - This is the type of cable to use to connect a modem to - your FreeBSD system, and is also appropriate for some + This is the type of cable used to connect a modem to + the &os; system, and is also appropriate for some terminals. @@ -477,61 +470,61 @@ Ports Serial ports are the devices through which data is - transferred between the FreeBSD host computer and the + transferred between the &os; host computer and the terminal. This section describes the kinds of ports that - exist and how they are addressed in FreeBSD. + exist and how they are addressed in &os;. Kinds of Ports - Several kinds of serial ports exist. Before you - purchase or construct a cable, you need to make sure it - will fit the ports on your terminal and on the FreeBSD + Several kinds of serial ports exist. Before + purchasing or constructing a cable, make sure it will + fit the ports on the terminal and on the &os; system. - Most terminals will have DB-25 ports. Personal - computers, including PCs running FreeBSD, will have DB-25 - or DB-9 ports. If you have a multiport serial card for - your PC, you may have RJ-12 or RJ-45 ports. + Most terminals have DB-25 ports. Personal computers + may have DB-25 or DB-9 ports. A multiport serial card may + have RJ-12 or RJ-45 ports. See the documentation that accompanied the hardware - for specifications on the kind of port in use. A visual - inspection of the port often works too. + for specifications on the kind of port or visually verify + the type of port. Port Names - In FreeBSD, you access each serial port through an - entry in the /dev directory. There - are two different kinds of entries: + In &os;, each serial port is accessed through an + entry in /dev. + There are two different kinds of entries: Call-in ports are named /dev/ttyuN where N is the port number, - starting from zero. Generally, you use the call-in - port for terminals. Call-in ports require that the - serial line assert the data carrier detect (DCD) - signal to work correctly. + starting from zero. Generally, the call-in port is + used for terminals. Call-in ports require that the + serial line assert the Data Carrier Detect + (DCD) signal to work + correctly. Call-out ports are named /dev/cuauN. - You usually do not use the call-out port for - terminals, just for modems. You may use the call-out - port if the serial cable or the terminal does not - support the carrier detect signal. + Call-out ports are usually not used for terminals, but + are used for modems. The call-out port can be used if + the serial cable or the terminal does not support the + carrier detect signal. - If you have connected a terminal to the first serial - port(COM1 in &ms-dos;), then you - will use /dev/ttyu0 to refer to the + If a terminal is connected to the first serial + port(COM1), use + /dev/ttyu0 to refer to the terminal. If the terminal is on the second serial port - (also known as COM2), use + (COM2), use /dev/ttyu1, and so forth. @@ -541,25 +534,25 @@ Kernel Configuration - FreeBSD supports four serial ports by default. In the + &os; supports four serial ports by default. In the &ms-dos; world, these are known as COM1, COM2, COM3, and - COM4. FreeBSD currently supports + COM4. &os; currently supports dumb multiport serial interface cards, such as - the BocaBoard 1008 and 2016, as well as more - intelligent multi-port cards such as those made by Digiboard - and Stallion Technologies. However, the default kernel only - looks for the standard COM ports. - - To see if your kernel recognizes any of your serial ports, - watch for messages while the kernel is booting, or use the - /sbin/dmesg command to replay the kernel's - boot messages. In particular, look for messages that start - with the characters uart if you use - &os; 8.0 or higher, or sio for - &os; 7.4 or older. + the BocaBoard 1008 and 2016, as well as more intelligent + multi-port cards such as those made by Digiboard and Stallion + Technologies. However, the default kernel only looks for the + standard COM ports. + + To see if the kernel recognizes the serial ports, + watch for messages while the kernel is booting, or use + /sbin/dmesg to replay the kernel's + boot messages. Look for messages that start with the + characters uart for &os; 8.0 or + higher, or sio for &os; 7.4 or + older. To view just the messages that have the word uart or sio depending @@ -570,7 +563,7 @@ For example, on a &os; 7.X - system with four serial ports, these are the serial-port + system with four serial ports, these are the serial port specific kernel boot messages: sio0 at 0x3f8-0x3ff irq 4 on isa @@ -582,31 +575,30 @@ sio2: type 16550A sio3 at 0x2e8-0x2ef irq 9 on isa sio3: type 16550A - If your kernel does not recognize all of your serial - ports, you will probably need to configure your kernel - in the /boot/device.hints file. You can - also comment-out or completely remove lines for devices you - do not have. - - Please refer to the &man.sio.4; manual page for - more information on serial ports and multiport boards - configuration. Be careful if you are using a configuration - file that was previously used for a different version of - FreeBSD because the device flags and the syntax have changed - between versions. + If the kernel does not recognize all of the serial + ports, configure /boot/device.hints. + When editing this file, one can comment out or completely + remove lines for devices that do not exist on the + system. + + Refer to &man.sio.4; for more information on + configuring serial ports and multiport boards. When using a + configuration file that was previously used for a different + version of &os; be aware that the device flags and the syntax + may have changed between versions. port IO_COM1 is a substitution for port 0x3f8, IO_COM2 is 0x2f8, IO_COM3 is 0x3e8, and IO_COM4 is - 0x2e8, which are fairly common port - addresses for their respective serial ports; interrupts 4, - 3, 5, and 9 are fairly common interrupt request lines. Also - note that regular serial ports cannot - share interrupts on ISA-bus PCs (multiport boards have + 0x2e8. These are fairly common port + addresses for their respective serial ports and interrupts + 4, 3, 5, and 9 are fairly common interrupt request lines. + Regular serial ports cannot share + interrupts on ISA-bus PCs. Multiport boards have on-board electronics that allow all the 16550A's on the - board to share one or two interrupt request lines). + board to share one or two interrupt request lines. @@ -615,13 +607,13 @@ sio3: type 16550ADevice Special FilesMost devices in the kernel are accessed through - device special files, which are located in the - /dev directory. The + device special files which are located in + /dev class="directory". The sio devices are accessed through the /dev/ttyuN (dial-in) and /dev/cuauN - (call-out) devices. FreeBSD also provides initialization + (call-out) devices. &os; also provides initialization devices (/dev/ttyuN.init and @@ -635,9 +627,9 @@ sio3: type 16550A such as crtscts for modems which use RTS/CTS signaling for flow control. The locking devices are used to lock flags on ports to prevent - users or programs changing certain parameters; see the manual - pages &man.termios.4;, &man.sio.4;, and &man.stty.1; for - information on the terminal settings, locking and initializing + users or programs changing certain parameters. Refer to + &man.termios.4;, &man.sio.4;, and &man.stty.1; for + information on terminal settings, locking and initializing devices, and setting terminal options, respectively. @@ -651,20 +643,20 @@ sio3: type 16550AThe ttyuN (or cuauN) - device is the regular device you will want to open for your - applications. When a process opens the device, it will have a - default set of terminal I/O settings. You can see these - settings with the command + is the regular device to open for applications. When a + process opens the device, it will have a default set of + terminal I/O settings. These settings can be viewed with the + command:&prompt.root; stty -a -f /dev/ttyu1 - When you change the settings to this device, the settings - are in effect until the device is closed. When it is - reopened, it goes back to the default set. To make changes to - the default set, you can open and adjust the settings of the + When the settings are changed for a device, the settings + are in effect until the device is closed. When the device is + reopened, it goes back to the default set. To permanently + change the default set, open and adjust the settings of the initial state device. For example, to turn on mode, 8 bit communication, and - flow control by default for + flow control for ttyu5, type: &prompt.root; stty -f /dev/ttyu5.init clocal cs8 ixon ixoff @@ -674,8 +666,8 @@ sio3: type 16550A rc.serial - System-wide initialization of the serial devices is - controlled in /etc/rc.d/serial. This + System-wide initialization of serial devices is + controlled by /etc/rc.d/serial. This file affects the default settings of serial devices. To prevent certain settings from being changed by an @@ -689,9 +681,8 @@ sio3: type 16550A ttyu5 and tries to change the speed of the port will be stuck with 57600 bps. - Naturally, you should make the initial state and lock - state devices writable only by the root - account. + The initial state and lock state devices should only be + writable by root. @@ -708,120 +699,85 @@ sio3: type 16550A Terminals - - As of &os; 8.0, device nodes for serial ports have been - renamed from - /dev/cuadN to - /dev/cuauN and - from - /dev/ttydN to - /dev/ttyuN. - &os; 7.X users will have to adapt the following - documentation according to these changes. - - terminals Terminals provide a convenient and low-cost way to access - your FreeBSD system when you are not at the computer's console - or on a connected network. This section describes how to use - terminals with FreeBSD. + a &os; system when not at the computer's console or on a + connected network. This section describes how to use terminals + with &os;. Uses and Types of Terminals The original &unix; systems did not have consoles. - Instead, people logged in and ran programs through terminals - that were connected to the computer's serial ports. It is - quite similar to using a modem and terminal software to dial - into a remote system to do text-only work. - - Today's PCs have consoles capable of high quality - graphics, but the ability to establish a login session on a - serial port still exists in nearly every &unix; style - operating system today; FreeBSD is no exception. By using a - terminal attached to an unused serial port, you can log in and - run any text program that you would normally run on the - console or in an xterm window in the X - Window System. - - For the business user, you can attach many terminals to a - FreeBSD system and place them on your employees' desktops. - For a home user, a spare computer such as an older IBM PC or a - &macintosh; can be a terminal wired into a more powerful - computer running FreeBSD. You can turn what might otherwise be - a single-user computer into a powerful multiple user - system. - - For FreeBSD, there are three kinds of terminals: + Instead, users logged in and ran programs through terminals + that were connected to the computer's serial ports. - - - Dumb terminals - - - - PCs acting as - terminals - - - - X terminals - - - - The remaining subsections describe each kind. + The ability to establish a login session on a serial port + still exists in nearly every &unix;-like operating system + today, including &os;. By using a terminal attached to an + unused serial port, a user can log in and run any text program + that can normally be run on the console or in an + xterm window. + + Many terminals can be attached to a &os; system. An older + spare computer can be used as a terminal wired into a more + powerful computer running &os;. This can turn what might + otherwise be a single-user computer into a powerful multiple + user system. + + This section describes three kinds of terminals supported + by &os;: dumb terminals, computers acting as terminals, and X + terminals. Dumb Terminals - Dumb terminals are specialized pieces of hardware that - let you connect to computers over serial lines. They are - called dumb because they have only enough - computational power to display, send, and receive text. You - cannot run any programs on them. It is the computer to - which you connect them that has all the power to run text + Dumb terminals are specialized hardware that connect to + computers over serial lines. They are called + dumb because they have only enough + computational power to display, send, and receive text. No + programs can be run on these devices. Dumb terminals + connect to a computer that has all the power to run text editors, compilers, email, games, and so forth. There are hundreds of kinds of dumb terminals made by - many manufacturers, including Digital Equipment - Corporation's VT-100 and Wyse's WY-75. Just about any kind - will work with FreeBSD. Some high-end terminals can even - display graphics, but only certain software packages can - take advantage of these advanced features. + many manufacturers, and just about any kind will work with + &os;. Some high-end terminals can even display graphics, + but only certain software packages can take advantage of + these advanced features. Dumb terminals are popular in work environments where - workers do not need access to graphical applications such as - those provided by the X Window System. + workers do not need access to graphical applications. - PCs Acting as Terminals + Computers Acting as Terminals If a dumb terminal has - just enough ability to display, send, and receive text, then - certainly any spare personal computer can be a dumb - terminal. All you need is the proper cable and some - terminal emulation software to run on - the computer. - - Such a configuration is popular in homes. For example, - if your spouse is busy working on your FreeBSD system's - console, you can do some text-only work at the same time - from a less powerful personal computer hooked up as a - terminal to the FreeBSD system. + just enough ability to display, send, and receive text, + any spare computer can be a dumb terminal. All that is + needed is the proper cable and some terminal + emulation software to run on the + computer. + + This configuration can be useful. For example, if one + user is busy working at the &os; system's console, another + user can do some text-only work at the same time from a + less powerful personal computer hooked up as a terminal to + the &os; system. There are at least two utilities in the base-system of &os; that can be used to work through a serial connection: &man.cu.1; and &man.tip.1;. To connect from a client system that runs &os; to the - serial connection of another system, you can use: + serial connection of another system, use: &prompt.root; cu -l serial-port-device Where serial-port-device is the name of a - special device file denoting a serial port of your system. + special device file denoting a serial port on the system. These device files are called /dev/cuauN. @@ -830,17 +786,13 @@ sio3: type 16550A Note that device numbers in &os; start from zero and - not one (like they do, for instance in &ms-dos;-derived - systems). This means that what &ms-dos;-based systems - call COM1 is usually + not one. This means that COM1 is /dev/cuau0 in &os;. - Some people prefer to use other programs, available - through the Ports Collection. The Ports include quite a - few utilities which can work in ways similar to &man.cu.1; - and &man.tip.1;, i.e., Some people prefer to use other programs available + through the Ports Collection, such as comms/minicom. @@ -854,48 +806,44 @@ sio3: type 16550A being relegated to text-only applications, they can display any X application. - We introduce X terminals just for the sake of - completeness. However, this chapter does - not cover setup, configuration, or use - of X terminals. + This chapter does not cover the + setup, configuration, or use of X terminals. Configuration - This section describes what you need to configure on your - FreeBSD system to enable a login session on a terminal. It - assumes you have already configured your kernel to support the - serial port to which the terminal is connected—and that - you have connected it. - - Recall from that the - init process is responsible for all process - control and initialization at system startup. One of the - tasks performed by init is to read the - /etc/ttys file and start a + This section describes how to configure a &os; system to + enable a login session on a terminal. It assumes that the + kernel is configured to support the serial port to which the + terminal is connected and that the terminal is + connected. + + The init process is responsible for all + process control and initialization at system startup. One of + the tasks performed by init is to read + /etc/ttys and start a getty process on the available terminals. The getty process is responsible for reading a login name and starting the login program. - Thus, to configure terminals for your FreeBSD system the - following steps should be taken as - root: + To configure terminals for a &os; system, the following + steps should be taken as root: Add a line to /etc/ttys for the - entry in the /dev directory for the - serial port if it is not already there. + entry in /dev for + the serial port if it is not already there. Specify that /usr/libexec/getty be run on the port, and specify the appropriate - getty type from the - /etc/gettytab file. + getty type from + /etc/gettytab. @@ -912,53 +860,53 @@ sio3: type 16550A - Force init to reread the - /etc/ttys file. + Force init to reread + /etc/ttys. - As an optional step, you may wish to create a custom + As an optional step, create a custom getty type for use in step 2 by - making an entry in /etc/gettytab. This - chapter does not explain how to do so; you are encouraged to - see the &man.gettytab.5; and the &man.getty.8; manual pages - for more information. + making an entry in /etc/gettytab. For + more information, refer to &man.gettytab.5; and + &man.getty.8;. Adding an Entry to <filename>/etc/ttys</filename> - The /etc/ttys file lists all of the - ports on your FreeBSD system where you want to allow logins. - For example, the first virtual console - ttyv0 has an entry in this file. - You can log in on the console using this entry. This - file also contains entries for the other virtual consoles, - serial ports, and pseudo-ttys. For a hardwired terminal, - just list the serial port's /dev entry - without the /dev part (for example, + /etc/ttys lists all of the ports + on the &os; system which allow logins. For example, the + first virtual console, + ttyv0, has an entry in this file, + allowing logins on the console. This file also contains + entries for the other virtual consoles, serial ports, and + pseudo-ttys. For a hardwired terminal, + list the serial port's /dev entry without the + /dev part. For example, /dev/ttyv0 would be listed as - ttyv0). + ttyv0. - A default FreeBSD install includes an - /etc/ttys file with support for the + A default &os; install includes an + /etc/ttys with support for the first four serial ports: ttyu0 - through ttyu3. If you are - attaching a terminal to one of those ports, you do not need - to add another entry. + through ttyu3. When + attaching a terminal to one of those ports, this file does + not need to be edited. Adding Terminal Entries to <filename>/etc/ttys</filename> - Suppose we would like to connect two terminals to the - system: a Wyse-50 and an old 286 IBM PC running + This example configures two terminals: a Wyse-50 and + an old 286 IBM PC running Procomm terminal software - emulating a VT-100 terminal. We connect the Wyse to the - second serial port and the 286 to the sixth serial port (a - port on a multiport serial card). The corresponding - entries in the /etc/ttys file would - look like this: + emulating a VT-100 terminal. The Wyse is connected to the + second serial port and the 286 to the sixth serial port on + a multiport serial card. The corresponding entries in + /etc/ttys would look like + this: ttyu1 "/usr/libexec/getty std.38400" The first field normally specifies the name of the terminal special file as it is found in - /dev. + /dev. The second field is the command to execute for this line, which is usually &man.getty.8;. getty initializes and opens the - line, sets the speed, prompts for a user name and then - executes the &man.login.1; program. + line, sets the speed, prompts for a user name, and + then executes &man.login.1;. The getty program accepts one (optional) parameter on its command line, the getty type. A getty type configures - characteristics on the terminal line, like bps rate - and parity. The getty program - reads these characteristics from the file - /etc/gettytab. - - The file /etc/gettytab - contains lots of entries for terminal lines both old - and new. In almost all cases, the entries that start - with the text std will work for - hardwired terminals. These entries ignore parity. - There is a std entry for each bps - rate from 110 to 115200. Of course, you can add your - own entries to this file. The &man.gettytab.5; manual - page provides more information. + characteristics on the terminal line, like + bps rate and parity. + getty reads these characteristics + from /etc/gettytab. + + /etc/gettytab contains many + entries for terminal lines, both old and new. In + almost all cases, the entries that start with the + text std will work for hardwired + terminals as these entries ignore parity. There is + a std entry for each + bps rate from 110 to 115200. + &man.gettytab.5; provides more information. When setting the getty - type in the /etc/ttys file, make - sure that the communications settings on the terminal + type in /etc/ttys, make sure + that the communications settings on the terminal match. - For our example, the Wyse-50 uses no parity and + For this example, the Wyse-50 uses no parity and connects at 38400 bps. The 286 PC uses no parity and connects at 19200 bps. The third field is the type of terminal usually - connected to that tty line. For dial-up ports, + connected to that terminal line. For dial-up ports, unknown or - dialup is typically used in this - field since users may dial up with practically any - type of terminal or software. For hardwired - terminals, the terminal type does not change, so you - can put a real terminal type from the &man.termcap.5; - database file in this field. + dialup is typically used since + users may dial up with practically any type of + terminal or software. Since the terminal type does + not change for hardwired terminals, a real terminal + type from &man.termcap.5; can be used in this + field. - For our example, the Wyse-50 uses the real + For this example, the Wyse-50 uses the real terminal type while the 286 PC running Procomm will be set to emulate at VT-100. @@ -1030,30 +977,31 @@ ttyu5 "/usr/libexec/getty std.19200" The fourth field specifies if the port should be - enabled. Putting on here will have - the init process start the program - in the second field, getty. If you - put off in this field, there will - be no getty, and hence no logins on - the port. + enabled. If set to on, the + init process will start the program + in the second field, getty. If + this field is set to off, there + will be no getty, and hence no + logins on the port. The final field is used to specify whether the - port is secure. Marking a port as secure means that - you trust it enough to allow the - root account (or any account with - a user ID of 0) to login from that port. Insecure - ports do not allow root logins. - On an insecure port, users must login from - unprivileged accounts and then use &man.su.1; or a - similar mechanism to gain superuser privileges. - - It is highly recommended that you use - insecure - even for terminals that are behind locked doors. It - is quite easy to login and use su - if you need superuser privileges. + port is secure. Marking a port as + secure means that it is trusted + enough to allow root, or any + account with a UID of 0, to login + from that port. Insecure ports do not allow + root logins. On an insecure + port, users must login from unprivileged accounts and + then use &man.su.1; or a similar mechanism to gain + superuser privileges. + + It is highly recommended to use + insecure, even for terminals that + are behind locked doors. It is quite easy to login + and use su when superuser + privileges are needed. @@ -1063,34 +1011,34 @@ ttyu5 "/usr/libexec/getty std.19200" Force <command>init</command> to Reread <filename>/etc/ttys</filename> - After making the necessary changes to the - /etc/ttys file you should send a SIGHUP + After making any changes to + /etc/ttys, send a SIGHUP (hangup) signal to the init process to - force it to re-read its configuration file. For - example: + force it to re-read its configuration file: &prompt.root; kill -HUP 1 init is always the first process - run on a system, therefore it will always have PID - 1. + run on a system, therefore it will always have a process + ID of 1. If everything is set up correctly, all cables are in place, and the terminals are powered up, then a getty process should be running on each - terminal and you should see login prompts on your terminals - at this point. + terminal and login prompts should be available on each + terminal. *** DIFF OUTPUT TRUNCATED AT 1000 LINES ***