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diff --git a/share/doc/psd/05.sysman/2.4.t b/share/doc/psd/05.sysman/2.4.t new file mode 100644 index 0000000..cd7dcb9 --- /dev/null +++ b/share/doc/psd/05.sysman/2.4.t @@ -0,0 +1,174 @@ +.\" Copyright (c) 1983, 1993 +.\" The Regents of the University of California. All rights reserved. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" 3. All advertising materials mentioning features or use of this software +.\" must display the following acknowledgement: +.\" This product includes software developed by the University of +.\" California, Berkeley and its contributors. +.\" 4. Neither the name of the University nor the names of its contributors +.\" may be used to endorse or promote products derived from this software +.\" without specific prior written permission. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND +.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE +.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS +.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY +.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +.\" SUCH DAMAGE. +.\" +.\" @(#)2.4.t 8.1 (Berkeley) 6/8/93 +.\" +.sh "Terminals and Devices +.NH 3 +Terminals +.PP +Terminals support \fIread\fP and \fIwrite\fP I/O operations, +as well as a collection of terminal specific \fIioctl\fP operations, +to control input character interpretation and editing, +and output format and delays. +.NH 4 +Terminal input +.PP +Terminals are handled according to the underlying communication +characteristics such as baud rate and required delays, +and a set of software parameters. +.NH 5 +Input modes +.PP +A terminal is in one of three possible modes: \fIraw\fP, \fIcbreak\fP, +or \fIcooked\fP. +In raw mode all input is passed through to the +reading process immediately and without interpretation. +In cbreak mode, the handler interprets input only by looking +for characters that cause interrupts or output flow control; +all other characters are made available as in raw mode. +In cooked mode, input +is processed to provide standard line-oriented local editing functions, +and input is presented on a line-by-line basis. +.NH 5 +Interrupt characters +.PP +Interrupt characters are interpreted by the terminal handler only in +cbreak and cooked modes, and +cause a software interrupt to be sent to all processes in the process +group associated with the terminal. Interrupt characters exist +to send SIGINT +and SIGQUIT signals, +and to stop a process group +with the SIGTSTP signal either immediately, or when +all input up to the stop character has been read. +.NH 5 +Line editing +.PP +When the terminal is in cooked mode, editing of an input line +is performed. Editing facilities allow deletion of the previous +character or word, or deletion of the current input line. +In addition, a special character may be used to reprint the current +input line after some number of editing operations have been applied. +.PP +Certain other characters are interpreted specially when a process is +in cooked mode. The \fIend of line\fP character determines +the end of an input record. The \fIend of file\fP character simulates +an end of file occurrence on terminal input. Flow control is provided +by \fIstop output\fP and \fIstart output\fP control characters. Output +may be flushed with the \fIflush output\fP character; and a \fIliteral +character\fP may be used to force literal input of the immediately +following character in the input line. +.PP +Input characters may be echoed to the terminal as they are received. +Non-graphic ASCII input characters may be echoed as a two-character +printable representation, ``^character.'' +.NH 4 +Terminal output +.PP +On output, the terminal handler provides some simple formatting services. +These include converting the carriage return character to the +two character return-linefeed sequence, +inserting delays after certain standard control characters, +expanding tabs, and providing translations +for upper-case only terminals. +.NH 4 +Terminal control operations +.PP +When a terminal is first opened it is initialized to a standard +state and configured with a set of standard control, editing, +and interrupt characters. A process +may alter this configuration with certain +control operations, specifying parameters in a standard structure:\(dg +.FS +\(dg The control interface described here is an internal interface only +in 4.3BSD. Future releases will probably use a modified interface +based on currently-proposed standards. +.FE +.DS +._f +struct ttymode { + short tt_ispeed; /* input speed */ + int tt_iflags; /* input flags */ + short tt_ospeed; /* output speed */ + int tt_oflags; /* output flags */ +}; +.DE +and ``special characters'' are specified with the +\fIttychars\fP structure, +.DS +._f +struct ttychars { + char tc_erasec; /* erase char */ + char tc_killc; /* erase line */ + char tc_intrc; /* interrupt */ + char tc_quitc; /* quit */ + char tc_startc; /* start output */ + char tc_stopc; /* stop output */ + char tc_eofc; /* end-of-file */ + char tc_brkc; /* input delimiter (like nl) */ + char tc_suspc; /* stop process signal */ + char tc_dsuspc; /* delayed stop process signal */ + char tc_rprntc; /* reprint line */ + char tc_flushc; /* flush output (toggles) */ + char tc_werasc; /* word erase */ + char tc_lnextc; /* literal next character */ +}; +.DE +.NH 4 +Terminal hardware support +.PP +The terminal handler allows a user to access basic +hardware related functions; e.g. line speed, +modem control, parity, and stop bits. A special signal, +SIGHUP, is automatically +sent to processes in a terminal's process +group when a carrier transition is detected. This is +normally associated with a user hanging up on a modem +controlled terminal line. +.NH 3 +Structured devices +.PP +Structures devices are typified by disks and magnetic +tapes, but may represent any random-access device. +The system performs read-modify-write type buffering actions on block +devices to allow them to be read and written in a totally random +access fashion like ordinary files. +File systems are normally created in block devices. +.NH 3 +Unstructured devices +.PP +Unstructured devices are those devices which +do not support block structure. Familiar unstructured devices +are raw communications lines (with +no terminal handler), raster plotters, magnetic tape and disks unfettered +by buffering and permitting large block input/output and positioning +and formatting commands. |
