1 .TH sympathy 1 "%VERSIONSTAMP%" "%LONGVERSION%" "USER COMMANDS"
2 .\" $Id: sympathy.1,v 1.28 2008/05/09 12:31:55 james Exp $
4 sympathy \- client/server terminal emulator with logging
8 .B \fIterminal_options\fP
10 .B \fIdisplay_options\fP
15 .B \fIterminal_options\fP
17 .B \fIserver_options\fP
22 .B \-\fBc\fP \-\fBs\fP
24 .B \fIterminal_options\fP
26 .B \fIserver_options\fP
28 .B \fIclient_options\fP
30 .B \fIdisplay_options\fP
35 .B \fIclient_options\fP
37 .B \fIdisplay_options\fP
43 .B \fIclient_options\fP
45 .B \fIdisplay_options\fP
48 .B sympathy \-\fBC\fP \-\fBd\fP
51 .B sympathy \-\fBls\fP
57 is a replacement for screen(1), minicom(1) and consolidate(1). It
58 is a VT52/VT100/ANSI terminal emulator with some special features. In normal use
60 would sit between a terminal device (a serial port or a pseudo-tty) and
61 the user's usual terminal emulator (eg xterm(1)).
63 renders data from the terminal device into an internal frame buffer
64 and then expresses changes in this frame buffer to the outer terminal
65 emulator using a small subset of ANSI escape codes.
67 always generates valid escape codes to the outer terminal, and will
68 reset the state of its internal terminal emulator when it detects
69 receive errors on the terminal device.
72 unlike screen(1), takes care to preserve the scroll-back features
73 of the outer terminal emulator: lines that scroll off the top of the internal
74 frame buffer are scrolled off the top of the outer terminal emulator. When
76 is used in client/server mode, some history is added to the outer
77 terminal emulator when the client connects.
80 also supports automatic baud\-rate detection, and advanced logging features.
82 logs whenever any of the modem control lines change state, receive errors,
84 of any line on the frame buffer as the cursor moves off it.
86 .B \fImajor mode options\fP:
91 will remove inactive lockfiles for the specified serial device, and then exit.
93 .B \-c\fP or \fB\-r\fP \fIid\fP
98 server process and injects the history into the outer terminal
100 and connects the user with the terminal device. One server process can support multiple
101 client processes. This mode can also be used to obtain a dump of the current screen
102 in HTML format (see the \-\fBH\fP option), inject key\-presses (see \-\fBI\fP)
103 or allow control via a dumb terminal (see \-\fBN\fP).
104 The \-\fPr\fP option connects to a
105 server process socket called \fIid\fP, or if \fIid\fP is an integer
106 \fIhost-name\fP.\fIid\fP mimicking the behaviour of screen(1).
108 searches for the socket in the following directories: \fI~/.sympathy\fP,
109 \fI~/sympathy\fP, \fI/etc/sympathy\fP, \fI/var/sympathy\fP.
110 With the \-\fBc\fP option the socket must be specified with the \-\fBk\fP
113 .B \fP[\fB \-c \-s \fP]
114 act as both client and server:
116 forks. The child process becomes a server, and the original process becomes a client
117 which then connects to the server. This is the default major mode if no other is specified.
118 Since the default terminal device is a pseudo-tty, running
120 with no arguments will start a new shell in a daemonised process and connect to it
121 as a client from the original process, mimicking the behaviour of screen(1)
126 will show active sockets, ones to which a call to connect(2) succeeds,
127 in ~/.sympathy. If the socket name begins with the host-name of the machine, and
128 the call to connect(2) fails, then socket will be unlinked.
133 opens the terminal device and renders into an internal frame buffer, listens for clients
134 on the socket and logs activity. By default the server will fork into a daemon process
135 but can be forced to remain in the foreground with the \-\fBF\fP option.
138 act as terminal emulator only:
140 opens the terminal device and outputs into the outer terminal emulator. When
141 .I sympathy exits the
142 device is closed and no process remains. In this mode
144 behaves like a traditional
145 terminal emulator such as cu(1) or minicom(1).
148 show current version:
150 will print the the version number of the code it was compiled from.
155 will show brief usage instructions
157 .B \fIterminal_options\fP:
159 .B \-d \fIserialdev\fP
160 connect to terminal device \fIserialdev\fP, eg /dev/ttyS0.
164 lock the terminal device, but checks periodically for lock files of other processes. If
166 detects another lock file it displays \fBLocked\fP in the status line
167 and refuses I/O on the device until the lock file is removed or becomes invalid.
168 To lock the device use the \-\fBK\fP option.
170 will in addition check that the name of the device does not occur in /proc/cmdline
171 as an argument to the \fIconsole\fP kernel parameter.
172 The \-\fBd\fP option is incompatible with the \-\fBp\fP option.
175 connect to a pseudo\-tty instead of a terminal device, and fork a login shell in
176 it. The \-\fBp\fP option is incompatible with the \-\fBd\fP option. This is the default
177 terminal device if none is specified. The first non\-option command line
178 arugment is considered to be the a binary to run in the pseudo\-tty, subsequent
179 arguments are parsed to the binary. The current value of PATH is searched for
180 the binary if it does not start with '/'. If no binary is specified
181 then '/bin/sh' is called with \fIargv[0]\fP set to '\-'.
184 lock the terminal device specified in the \-\fBd\fP option.
186 generates lock files in a staggering variety of formats and places. For locks
187 based on the name of the device
189 generates lock files for all devices
190 with the same major and minor in /dev, /dev/usb and /dev/tts, it uses both
191 normal and lower case and replaces occurrences of `/' in the device name with
194 also generates locks based on the device major and minor numbers, and for all lock file
195 names generates them in any of the following directories that are writable:
196 /var/lock/uucp, /var/spool/lock, /var/spool/uucp, /etc/locks, /usr/spool/uucp,
197 /var/spool/locks, /usr/spool/lock, /usr/spool/locks, /usr/spool/uucp/LCK, /var/lock.
198 Lock files are assumed to be in HDB format.
200 .B \-b \fIbaud\-rate\fP
201 set the baud\-rate of the terminal device specified in the \-\fBd\fP to
202 \fIbaud\-rate\fP, if omitted the current baud\-rate of the serial port will be
206 turn on flow control on the terminal device. This option adds \fICRTSCTS\fP to
207 \fIsympathy\fP's default
208 \fIc_cflag\fPs of \fICS8|CREAD|CLOCAL\fP.
211 log activity to the file \fIlogfile\fP. If \fIlogfile\fP is `-' then log to
212 \fIstdout\fP. Note that logging to \fIstdout\fP only makes sense with the
213 \-\fBF\fP \fIserver_option\fP.
215 will also close and reopen its log file when it receives a \fBSIGHUP\fP, which
216 with the \fB\-P\fP allows the use of logrotate(8).
219 write the pid of the server/terminal process to \fIpidfile\fP, which is
220 removed on clean exit.
223 rotate log files. When the log\-file specified with the \fB\-L\fP option
226 will rotate it and compress old log\-files.
228 .B \-w \fIwidth\fP[x\fIheight\fP]
229 set the initial size of the terminal emulator's frame buffer to be \fIwidth\fP columns
230 by \fIheight\fP rows. If \fIheight\fP is omitted it defaults to 24, the default width
231 is 80. These values may
232 be overridden later by terminal escape sequences. If \-\fBp\fP is also specified
233 the pseudo-tty will have its window size set to match.
235 .B \fIdisplay_options\fP:
238 attempt to render Unicode characters in the internal frame buffer to the outer terminal
239 emulator by using ISO-2202 sequences.
241 currently only checks to see if an appropriate character appears in the VT102
242 US character set, or in the VT102 `special characters and line drawing' character set.
243 If the character appears in neither of these then it will be rendered on the outer
244 terminal emulator as a `?'.
247 render the current state of the internal frame buffer to \fIstdout\fP as HTML, then quit.
250 don't render the internal frame buffer using ANSI characters, but instead write characters
251 that would be written to the screen to stdout. Take characters from stdin and send them
252 to the device. This feature is useful when you wish to use sympathy in conjunction with programs
255 .B \fIclient_options\fP:
258 set the name in the file-system of the socket to which
260 should connect. This option is \fBmandatory\fP unless the \-\fBs\fP or \-\fBr\fP options
261 have also been given. If \-\fBs\fP is given then it will default to the socket which
262 the forked server process opens. See the discussion of the \-\fPr\fP option above, for
265 chooses a socket name if \-\fBr\fP is specified.
268 Inject \fIstring\fP to the device as if it had been typed at the keyboard. Each character in
269 the string is treated as a key\-press.
271 recognizes various common escapes for control characters. Other keys, for example the arrow keys,
272 are mapped to character codes between 128 and 255, see src/keys.h for details.
274 .B \fIserver_options\fP:
279 server process not to become a daemon but to remain the the foreground. This option is
280 incompatible with the \-\fBc\fP \-\fBs\fP major mode.
283 set the name in the file-system of the socket on which
285 should listen for clients. If this option is omitted
288 socket in ~/.sympathy, creating that directory if necessary, and named
289 \fIhost-name\fP.\fIpid\fP where \fIpid\fP is the process id of the
291 process that created the socket.
294 sets the number of lines of history that the server process stores to \fInlines\fP. When
295 a client connects \fInlines\fP of history are injected into the outer terminal emulator
296 so that they can be seen when scrolling back. By default the server stores 200 lines of
302 server process to log errors to syslog.
306 is relaying data to the outer terminal emulator a reverse video status line
307 will be visible at the bottom of the screen. The status line shows pertinent
308 information. The first item on the line reminds you what the current escape character
309 is, the second indicates the terminal device to which
311 is connected, and the third shows the current baud\-rate. Other messages are:
314 indicates that that RTS/CTS flow control is in operation on the terminal device.
317 indicates that the terminal device is asserting the RTS line which indicates that
318 the local system is ready to accept data from the remote system. If RTS/CTS
319 flow control is in operation then the operating system or hardware may
320 de-assert RTS even if RTS is shown. See the section on SERIAL PORT THEORY for
324 indicates that the terminal device has detected that the local system's CTS
325 line is being asserted, indicating that the remote system is ready to receive
326 data from the local system. See the section on SERIAL PORT THEORY for
330 indicates that the terminal device is asserting the DTR line indicating that the local
331 system would like the local DCE to establish a connection to the remote
332 DCE. See the section on SERIAL PORT THEORY for more information.
335 indicates that the terminal device has detected that the local system's DSR line is
336 being asserted, indicating that the local DCE is ready. See the section on
337 SERIAL PORT THEORY for more information.
340 indicates that the terminal device has detected that the local system's CD line is
341 being asserted, indicating that the local DCE has a connection to the remote DCE.
342 See the section on SERIAL PORT THEORY for more information.
345 indicates that the terminal device has detected that the local system's RI line is
346 being asserted, indicating that the DCE has detected a ringing signal or incoming
350 shows the number of connected client processes. In the \-\fBt\fP major mode, this will
354 the terminal device was opened without the \-\fbK\fP flag and another process is
355 currently using it. I/O to the device is currently suspended until the process dies
356 or removes its lock file.
359 indicates the number of frames received by the terminal device with errors (indicating
360 the wrong parity, baud\-rate or framing). The count resets if no errors are
361 detected by the device for 10 seconds.
365 thinks that you have set the wrong baud\-rate and is unable to determine the correct
366 one as the current baud\-rate is lower than the correct baud\-rate. Use the \fBbaud\fP command
367 to set a higher baud\-rate (eg 115200) and
373 thinks that you have set the wrong baud\-rate and thinks that the correct baud\-rate is
374 \fIrate\fP. Use the \fBbaud\fP command to change the current baud\-rate.
376 Commands are entered by sending the escape character, ascii(7) STX, from the outer terminal
377 emulator (usually by pressing CTRL\-B), typing the command and pressing return. Whilst the
378 command is entered the status line changes to `:' and rudimentary line editing is available.
379 Whilst the command is entered the cursor \fBdoes not move\fP but remains where the terminal
380 emulator has placed it. Pressing the escape character whilst in command mode
381 will send the escape character to the terminal and cancel command mode. Valid
385 switch from VT102 behaviour to ANSI behaviour. The most noticeable difference is
386 the so\-called `xn' glitch.
389 switch from ANSI behaviour to VT102 behaviour.
392 set the current baud\-rate to nnnn
395 send the break signal by asserting the TX line for longer than a frame period.
398 enable RTS/CTS flow control
401 disable RTS/CTS flow control
404 de-assert DTR for one second.
407 set the current width of the screen to \fInn\fP, and reset the terminal emulator.
410 set the current height of the screen to \fInn\fP, and reset the terminal emulator.
413 reset the terminal emulator
416 expand the size of the screen to fit the size of the current outer terminal emulator window
419 exit this instance of
421 (disconnect from the server if present)
422 .SH CHARACTER ENCODINGS
423 For characters between 32 and 126
425 interprets them as would a VT102 terminal by following the subset of ISO-2202 that
426 the VT102 supports. Characters 128 thru 255 are assumed to be in UTF\-8(7), if
427 however the UTF\-8 is invalid they will instead be interpreted as characters
428 from ISO_8859-1(7). Character 155 (0x9b) when not part of a valid UTF\-8 sequence
429 will be interpreted as the one byte CSI character.
431 For the outer terminal emulator
433 by default issues the
434 ESC % G sequence to select UTF\-8 mode and emits valid UTF-8. If the outer terminal
435 does not, however, support UTF\-8 use the \-\fBu\fP switch to force
437 to use the VT102 subset of ISO-2202.
439 Log files are made exclusively in the UTF\-8 encoding. Each line in the log file
440 starts with the date and time at which the entry was made \- for example:
442 Feb 27 23:24:42.509440
445 logs a line to the file whenever the cursor leaves the line. Additionally
448 logs certain other events to the file:
450 serial port parameter changes: baud\-rate and flow control.
452 serial port control line state changes.
454 serial port line discipline errors.
458 suggested baud rates and bit frequency analyses.
460 transmission of breaks.
462 sending of the hangup signal (dropping the DTR line).
464 unknown or un\-handled messages sent on the socket.
466 connexion and disconnexion of clients.
470 invalid UTF-8 sequences.
472 terminal size changes
474 un\-handled terminal command sequences
476 The log file is rotated when it gets too large if the \fI\-R\fP option
477 is specified, and the log file is re-opened on receipt of a \fBSIGHUP\fP
478 which together with the \fB\-P\fP allows the use of of a program such
480 .SH AUTOMATIC BAUD RATE ALGORITHM
483 detects a framing error on the serial port it displays the count of
484 errors on the status line, and logs the error.
486 <tty reports error: \\377 \\000 \\000>
488 The count is reset to zero after ten seconds
489 have elapsed during which no errors have occurred.
491 looks at bit patterns of the characters received, and
492 measures the length (in units of the receiving UART's
493 bit period) of any runs of '1's delimited by '0's and vice\-versa. It
494 then calculates the statistics on the length of these runs, and logs these.
496 <tty_bit_analyse: 0000000001 [0,0,0,0,0,0,110,0,0,80]>
499 stream of ASCII data, the most common run length will be the correct bit
502 uses this together with the current bit period to calculate the most probable
503 correct baud\-rate, which is displayed in the status line, and logged.
504 If the correct baud\irate is higher than the current baud\-rate then the most common bit frequency will be '0' or '1' and the correct baud\-rate cannot be
505 determined. In this case sympathy will display and log the message 'try higher'.
507 <tty_analyse: 80 errors, current rate 115200b, suggest 19200b>
509 The algorithm only works well if the data stream is normal. If the data stream
510 is generated by the reception, at the wrong baud\-rate, of characters emitted
513 then the algorithm will be biased towards suggesting that the baud\-rate
514 is too low. Noise on the line will also result in sympathy concluding that
515 the baud\-rate is too low.
518 reacts to a set of signals. You can use the \fB-P\fP option
519 to easily determine the PID of the
521 process to which you would like to send a signal.
525 will immediately try to restore the outer terminal emulator to its original
530 will close and reopen the log-file specified with the -L option, which allows
531 the use of programs like logrotate(8)
535 will redraw the display in the outer terminal emulator so that it will fit within
536 the new display size.
540 will wait for children if some were born (for example from compressing rotated logs)
543 uses the \fBHOME\fP environment variable to determine the default
544 location for sockets.
547 sets the value of \fBTERM\fP in pseudo-ttys spawned using the
548 \-\fBp\fP argument to `xterm'.
551 will use \fBCSI ] 0 ;\fP to set the window title to the name of the
552 socket or device if \fBTERM\fP starts with \fIxterm\fP or \fIrxvt\fP.
554 The \fBPATH\fP enviroment variable is searched for the binary to be run
558 completely emulates a VT102 terminal (including the VT52 emulation).
560 also emulates a few extra sequences: the xterm(1) ESC ] ... sequences, and
561 the ANSI CSI @ and CSI b sequences. The numeric keypad follows exactly the
562 sequences produced by an xterm rather than the exact VT102/VT220 sequences.
564 also recognises the ESC % G and the ESC % @ sequences to switch between ISO-2202
565 and UTF\-8 but ignores them (see CHARACTER ENCODING below)
566 .SH SERIAL PORT THEORY
567 A serial connexion was originally envisaged to connect a DTE (Data Terminal Equipment)
568 to a DCE (Data Circuit-terminating Equipment). The DCE (some sort of modem) would assert
569 the DTE's (the computer or terminal) DSR line to indicate it was ready. The DTE would
570 assert DTR to indicate to the DCE that it should attempt a connexion to the remote DCE.
571 Once a connexion was established the DCE would assert the DTE's CD pin. Data could then
572 flow between the DTR and the remote DTE via the two DCEs. Flow control was provided
573 via the RTS and CTS lines. The DTE asserts RTS when it is capable of receiving new data,
574 and pauses its transmission of data when the CTS line is de-asserted. The local DCE
575 asserts CTS when the remote DCE detects RTS, and vice versa.
577 In modern usage the signals are slightly different, for a typical connexion using modems
578 DSR indicates that the modem is ready, a drop DTR is used to indicate to the
579 modem that it should break the connexion to the remote modem. CD indicates that
580 the local modem is connected to the remote modem, and CTS and RTS behave as before. Connexion
581 is established by in-band signalling before CD is asserted.
583 For a \fBnull modem\fP cable local DSR and DTR are wired to remote CD, local
584 CTS to remote RTS, and local RTS to remote CTS. Thus asserting local DTR
585 asserts local DSR and remote CD, and asserting local RTS asserts remote CTS.
587 When RTS/CTS flow control is in operation and the receive buffer becomes full,
588 the operating system, or the hardware, de-asserts RTS, causing (via the DCEs or
589 the null modem cable) a de-assertion of remote CTS which in turn causes the
590 remote DTE to cease transmission.
597 [foo@barhost ~]$ sympathy
600 forks. The child becomes a daemon server and launches a new shell in a
601 pseudo-tty, the original process becomes a client and connects to the server
602 and shows the output. The user then uses the new shell and after some time
603 either hangs up on the client or issues CTRL\-B quit, and the client detaches from
606 Later the user wishes to retrieve her session and to determine which sympathy
607 sessions are active and issues:
609 [foo@barhost ~]$ sympathy \-ls
611 /home/foo/.sympathy/barhost.8843 (Active)
615 The user then issues:
617 [foo@barhost ~]$ sympathy \-r 8843
619 and is reconnected to her session.
621 using sympathy to mimic minicom(1):
624 [foo@barhost ~]$ sympathy \-t \-d /dev/modem \-b 9600 \-K
627 opens the device /dev/modem and locks it, sets the baud\-rate to 9600 baud and disables
628 flow control. A VT102 terminal emulator then displays the data from the modem. The user
629 quits the emulator by issuing CTRL\-B quit, which unlocks the modem and exits
634 to mimic consolidate(1):
637 [foo@barhost ~]$ sympathy \-s \-d /dev/ttyS13 \-b 19200 \-K \-k /var/sympathy/13 \-L /var/sympathy/13.log -R
640 becomes a daemon and detaches from the current tty. It then opens the device
641 /dev/ttyS13 and locks it, sets the baud\-rate to 19200 baud and disables flow
644 then listens for clients connecting on the socket \fI/var/sympathy/13\fP, whilst logging
645 completed lines and changes in status to the file \fI/var/sympathy/13.log\fP,
646 rotating the log file when it gets too large.
648 A user wishing to see the current status of /dev/ttyS13 issues:
650 [foo@barhost ~]$ sympathy \-c \-k /var/sympathy/13
654 [foo@barhost ~]$ sympathy \-r 13
656 and the last 200 lines of history are injected into the history of her outer
657 terminal emulator and she is connected to /dev/ttyS13. The user disconnects from the
658 server by issuing CTRL\-B quit.
665 [foo@barhost ~]$ sympathy \-t \-L typescript
668 starts a shell in a ptty and logs completed lines to the file typescript. When the shell exits
670 will terminate, or the user can press CTRL-B which will close the ptty and send a hangup
671 to its controlling process.
673 screen(1) minicom(1) consolidate(1)
675 ANSI X3.64, ISO-6429, ECMA-48, ISO-2202, ISO-8859, ISO-10646, Digital Equipment Corp. VT102.
679 The command editor and parser should support better line editing.
681 It should be possible to change the escape character.
683 The HTML generated with the \-\fBH\fP option is ugly.
685 No useful error message is generated if opening the terminal device fails in the
686 \-\fBc\fP \-\fBs\fP major mode.
688 James McKenzie, james@fishsoup.dhs.org