*** empty log message ***

[sympathy.git] / sympathy.1

.TH sympathy 1  "%VERSIONSTAMP%" "%LONGVERSION%" "USER COMMANDS"
.\" $Id$
.SH NAME
sympathy \- client/server terminal emulator with logging
.SH SYNOPSIS
.B sympathy \-\fBt\fP
[
.B \fIterminal_options\fP
] [
.B \fIdisplay_options\fP
]
.br
.B sympathy \-\fBs\fP
[
.B \fIterminal_options\fP
] [
.B \fIserver_options\fP
]
.br
.B sympathy 
[
.B \-\fBc\fP \-\fBs\fP
] [
.B \fIterminal_options\fP
] [
.B \fIserver_options\fP
] [
.B \fIclient_options\fP
] [
.B \fIdisplay_options\fP
]
.br
.B sympathy \-\fBc\fP
[
.B \fIclient_options\fP
] [
.B \fIdisplay_options\fP
] 
.br
.B sympathy \-\fBr\fP
id
[
.B \fIclient_options\fP
] [
.B \fIdisplay_options\fP
] 
.br
.B sympathy \-\fBv\fP
.br
.SH DESCRIPTION
.I Sympathy
is a replacement for screen(1), minicom(1) and consolidate(1). It
is a VT52/VT100/ANSI terminal emulator with some special features. In normal use
.I sympathy
would sit between a terminal device (a serial port or a pseudo-tty) and
the user's usual terminal emulator (eg xterm(1)). 
.I Sympathy
renders data from the terminal device into an internal frame buffer
and then expresses changes in this frame buffer to the outer terminal
emulator using a small subset of ANSI escape codes. 
.I Sympathy 
always generates valid escape codes to the outer terminal, and will 
reset the state of its internal terminal emulator when it detects
receive errors on the terminal device.
.PP
.I Sympathy\fP,
unlike screen(1), takes care to preserve the scroll-back features
of the outer terminal emulator: lines that scroll of the top of the internal 
frame buffer are scrolled off the top of the outer terminal emulator. When
sympathy is used in client/server mode, some history is added to the outer 
terminal emulator when the client connects.
.PP
.I Sympathy
also supports automatic baud\-rate detection, and advanced logging features.
.I Sympathy
logs whenever any of the modem control lines change state, receive errors,
and the contents
of any line on the frame buffer as the cursor moves off it.
.SH OPTIONS
.B \fImajor mode options\fP:
.TP 5
.B \-t
act as terminal emulator only:
.I sympathy
opens the terminal device and outputs into the outer terminal emulator. When sympathy exits the 
device is closed and no process remains. In this mode sympathy behaves like a traditional
terminal emulator such as cu(1) or minicom(1).
.TP 5
.B \-s
act as server only:
.I sympathy
opens the terminal device and renders into an internal frame buffer, listens for clients
on the socket and logs activity. By default the server will fork into a daemon process
but can be forced to remain in the foreground with the \-\fBF\fP option.
.TP 5
.B \-c\fP or \fB\-r\fP \fIid\fP
act as client only:
.I sympathy
connects to a sympathy server process and injects the history into the outer terminal
emulator,
and connects the user with the terminal device. One server process can support multiple 
client processes. This mode can also be used to obtain a dump of the current screen
in HTML format (see the \-\fBH\fP option). The \-\fPr\fP option connects to a server
on the socket ~/.sympathy/\fIid\fP  or if \fIid\fP is an integer 
~/.sympathy/\fIhost-name\fP.\fIid\fP mimicking the behaviour of screen(1). With the 
\-\fBc\fP option the socket must be specified with the \-\fBk\fP option.
.TP 5
.B \fP[\fB \-c \-s \fP]
act as both client and server:
.I sympathy
forks. The child process becomes a server, and the original process becomes a client
which then connects to the server. This is the default major mode if no other is specified. 
Since the default terminal device is a pseudo-tty, running 
.I sympathy
with no arguments will start a new shell in a daemonised process and connect to it
as a client from the original process, mimicking the behaviour of screen(1)
.TP 5 
.B \-l\fP or \fB\-ls
show active sockets:
.I sympathy 
will show active sockets, ones to which a call to connect(2) succeeds, 
in ~/.sympathy. If the socket name begins with the host-name of the machine, and
the call to connect(2) fails, then socket will be unlinked. 
.TP 5 
.B \-v
show current version:
.I sympathy 
will print the the version number of the code it was compiled from.
.TP 5
.B \-h
show help:
.I sympathy 
will show brief usage instructions
.PP
.B \fIterminal_options\fP:
.TP 5
.B \-d \fIserialdev\fP
connect to terminal device \fIserialdev\fP, eg /dev/ttyS0. 
By default 
.I sympathy
doesn't
lock the terminal device, but checks periodically for lock files of other processes. If 
sympathy detects another lock file it displays \fBLocked\fP in the status line 
and refuses I/O on the device until the lock file is removed or becomes invalid.
To lock the device use the \-\fBK\fP option. 
.I Sympathy 
will in addition check that the name of the device does not occur in /proc/cmdline
as an argument to the \fIconsole\fP kernel parameter. 
The \-\fBd\fP option is incompatible with the \-\fBp\fP option. 
.TP 5
.B \-p
connect to a pseudo-tty instead of a terminal device, and fork a login shell in
it. The \-\fBp\fP option is incompatible with the \-\fBd\fP option. This is the default 
terminal device if none is specified.
.TP 5
.B \-K
lock the terminal device specified in the \-\fBd\fP option. 
.I Sympathy
generates lock files in a staggering variety of formats and places. For locks
based on the name of the device sympathy generates lock files for all devices
with the same major and minor in /dev, /dev/usb and /dev/tts, it uses both normal
and lower case and replaces occurrences of `/' in the device name with both `.' and `_'.
.I Sympathy
also generates locks based on the device major and minor numbers, and for all lock file
names generates them in any of the following directories that are writable:
/var/lock/uucp, /var/spool/lock, /var/spool/uucp, /etc/locks, /usr/spool/uucp, 
/var/spool/locks, /usr/spool/lock, /usr/spool/locks, /usr/spool/uucp/LCK, /var/lock. 
Lock files are assumed to be in HDB format.
.TP 5
.B \-b \fIbaud-rate\fP
set the baud\-rate of the terminal device specified in the \-\fBd\fP to
\fIbaud-rate\fP, if omitted the current baud-rate of the serial port will be
used.
.TP 5
.B \-f
turn on flow control on the terminal device. This option adds \fICRTSCTS\fP to sympathy's default 
\fIc_cflag\fPs of \fICS8|CREAD|CLOCAL\fP.
.TP 5
.B \-L \fIlogfile\fP
log activity to the file \fIlogfile\fP. If \fIlogfile\fP is `-' then log to \fIstdout\fP. Note
that logging to \fIstdout\fP only makes sense with the \-\fBF\fP \fIserver_option\fP. 
.TP 5
.B \-w \fIwidth\fP[x\fIheight\fP]
set the initialise size of the terminal emulator's frame buffer to be \fIwidth\fP columns
by \fIheight\fP rows. If \fIheight\fP is omitted it defaults to 24, the default width
is 80. These values may
be overridden later by terminal escape sequences. If \-\fBp\fP is also specified
the pseudo-tty will have its window size set to match.
.PP
.B \fIdisplay_options\fP:
.TP 5
.B \-u
attempt to render Unicode characters in the internal frame buffer to the outer terminal 
emulator by using ISO-2202 sequences. 
.I Sympathy
currently only checks to see if an appropriate character appears in the VT102 
US character set, or in the VT102 `special characters and line drawing' character set.
If the character appears in neither of these then it will be rendered on the outer
terminal emulator as a `?'.
.TP 5
.B \-H
render the current state of the internal frame buffer to \fIstdout\fP as HTML, then quit.
.PP
.B \fIclient_options\fP:
.TP 5
.B \-k \fIsocket\fP
set the name in the file-system of the socket to which
.I sympathy
should connect. This option is \fBmandatory\fP unless the \-\fBs\fP or \-\fBr\fP options
have also been given. If \-\fBs\fP is given then it will default to the socket which
the forked server process opens. See the discussion of the \-\fPr\fP option above, for
information on how 
.I sympathy 
chooses a socket name if \-\fBr\fP is specified.
.PP
.B \fIserver_options\fP:
.TP 5
.B \-k \fIsocket\fP
set the name in the file-system of the socket on which
.I sympathy
should listen for clients. If this option is omitted 
.I sympathy 
will create a 
socket in ~/.sympathy, creating that directory if necessary, and named
\fIhost-name\fP.\fIpid\fP where \fIpid\fP is the process id of the 
.I sympathy
process that created the socket.
.TP 5
.B \-F
tells the 
.I sympathy
server process not to become a daemon but to remain the the foreground. This option is
incompatible with the \-\fBc\fP \-\fBs\fP major mode.
.TP 5
.B \-n \fInlines\fP
sets the number of lines of history that the server process stores to \fInlines\fP. When 
a client connects \fInlines\fP of history are injected into the outer terminal emulator
so that they can be seen when scrolling back. By default the server stores 200 lines of
history.
.SH OPERATION
When 
.I sympathy
is relaying data to the outer terminal emulator a reverse video status line 
will be visible at the bottom of the screen. The status line shows pertinent
information. The first item on the line reminds you what the current escape character
is, the second indicates the terminal device to which 
.I sympathy
is connected, and the third shows the current baud-rate. Other messages are:
.TP 5
.B Flow
indicates that that RTS/CTS flow control is in operation on the terminal device.
.TP 5
.B RTS
indicates that the terminal device is asserting the RTS line which indicates that 
the local system is ready to accept data from the remote system. If RTS/CTS
flow control is in operation then the operating system or hardware may
de-assert RTS even if RTS is shown. See the section on SERIAL PORT THEORY for
more information.
.TP 5
.B CTS
indicates that the terminal device has detected that the local system's CTS
line is being asserted, indicating that the remote system is ready to receive
data from the local system. See the section on SERIAL PORT THEORY for
more information.
.TP 5
.B DTR
indicates that the terminal device is asserting the DTR line indicating that the local
system would like the local DCE to establish a connection to the remote
DCE.  See the section on SERIAL PORT THEORY for more information.
.TP 5
.B DSR
indicates that the terminal device has detected that the local system's DSR line is
being asserted, indicating that the local DCE is ready. See the section on
SERIAL PORT THEORY for more information.
.TP 5
.B CD
indicates that the terminal device has detected that the local system's CD line is
being asserted, indicating that the local DCE has a connection to the remote DCE.
See the section on SERIAL PORT THEORY for more information.
.TP 5
.B RI
indicates that the terminal device has detected that the local system's RI line is
being asserted, indicating that the DCE has detected a ringing signal or incoming 
connexion.
.TP 5
.B n clients
shows the number of connected client processes. In the \-\fBt\fP major mode, this will 
always be zero.
.TP 5
.B Locked
the terminal device was opened without the \-\fbK\fP flag and another process is
currently using it. I/O to the device is currently suspended until the process dies
or removes its lock file.
.TP 5
.B n errs
indicates the number of frames received by the terminal device with errors (indicating 
the wrong parity, baud\-rate or framing). The count resets if no errors are
detected by the device for 10 seconds.
.TP 5
.B try higher
.I Sympathy
thinks that you have set the wrong baud\-rate and is unable to determine the correct
one as the current baud\-rate is lower than the correct baud\-rate. Use the \fBbaud\fP command
to set a higher baud\-rate (eg 115200) and sympathy will try again.
.TP 5
.B try \fIrate\fBb 
.I Sympathy
thinks that you have set the wrong baud\-rate and thinks that the correct baud\-rate is
\fIrate\fP. Use the \fBbaud\fP command to change the current baud\-rate.
.SH COMMANDS
Commands are entered by sending the escape character, ascii(7) STX, from the outer terminal 
emulator (usually by pressing CTRL\-B), typing the command and pressing return. Whilst the
command is entered the status line changes to `:' and rudimentary line editing is available.
Whilst the command is entered the cursor \fBdoes not move\fP but remains where the terminal
emulator has placed it. Valid commands are:
.TP 7
.B ansi
switch from VT102 behaviour to ANSI behaviour. The most noticeable difference is 
the so called `xn' glitch.
.TP 7
.B noansi
switch from ANSI behaviour to VT102 behaviour.
.TP 7
.B baud \fInnnn\fB
set the current baud\-rate to nnnn
.TP 7
.B break
send the break signal by asserting the TX line for longer than a frame period.
.TP 7
.B flow
enable RTS/CTS flow control
.TP 7
.B noflow
disable RTS/CTS flow control
.TP 7
.B hangup
de-assert DTR for one second.
.TP 7
.B width \fInn\fB
set the current width of the screen to \fInn\fP, and reset the terminal emulator.
.TP 7
.B height \fInn\fB
set the current height of the screen to \fInn\fP, and reset the terminal emulator.
.TP 7
.B reset
reset the terminal emulator
.TP 7
.B quit
exit this instance of sympathy (disconnect from the server if present)
.SH CHARACTER ENCODINGS
For characters between 32 and 126 
.I sympathy
interprets them as would a VT102 terminal by following the subset of ISO-2202 that 
the VT102 supports. Characters 128 thru 255 are assumed to be in UTF\-8(7), if
however the UTF\-8 is invalid they will instead be interpreted as characters
from ISO_8859-1(7). Character 155 (0x9b) when not part of a valid UTF\-8 sequence
will be interpreted as the one byte CSI character.
.PP
For the outer terminal emulator sympathy by default issues the 
ESC % G sequence to select UTF\-8 mode and emits valid UTF-8. If the outer terminal
does not, however, support UTF\-8 use the \-\fBu\fP switch to force 
.I sympathy 
to use the VT102 subset of ISO-2202.
.SH LOG FILES
Log files are made exclusively in the UTF\-8 encoding. Each line in the log file
starts with the date and time at which the entry was made \- for example:
.IP
Feb 27 23:24:42.509440
.PP
.I Sympathy
logs a line to the file whenever the cursor leaves the line. Additionally sympathy
logs certain other events to the file. When the baud\-rate is changed 
.I sympathy
writes  <baud changed to 19200>. Whenever a modem control line changes state 
.I sympathy
appends <Modem lines changed: \fI+/\-line\fP ...> to the log. Where \fI+\fP
indicates that \fIline\fP was asserted and \fI-\fP indicates that it was de-asserted.
.I Sympathy 
writes a message of the form <size now nnnxnnn> whenever the screen size is
changed, either by escape sequences, or via a user command.
When the terminal device reports receive errors 
.I sympathy 
adds additional information to the log. It reports the character sequence reporting the error
.IP
<tty reports error: \\377 \\000 \\000>
.PP
the observed frequencies of the different bit periods
.IP 
<tty_bit_analyse: 0000000001  [0,0,0,0,0,0,110,0,0,80]>
.PP
and the conclusions of the baud\-rate guessing algorithm
.IP
<tty_analyse:     80 errors, current rate 115200b, suggest 19200b>
.PP
Invalid UTF\-8 sequences are also reported 
.IP
<invalid utf\-8 sequence: \\301>
.SH ENVIRONMENT
.I sympathy 
uses the \fBHOME\fP environment variable to determine the default
location for sockets.
.br
.I sympathy 
sets the value of \fBTERM\fP in pseudo-ttys spawned using the
\-\fBp\fP argument to `xterm'
.SH EMULATION
.I Sympathy
completely emulates a VT102 terminal (including the VT52 emulation). 
.I Sympathy 
also emulates a few extra sequences: the xterm(1) ESC ] ... sequences, and 
the ANSI CSI @ and CSI b sequences. The numeric keypad follows exactly the
sequences produced by an xterm rather than the exact VT102/VT220 sequences.
.I Sympathy
also recognises the ESC % G and the ESC % @ sequences to switch between ISO-2202
and UTF\-8 but ignores them (see CHARACTER ENCODING below)
.SH SERIAL PORT THEORY
A serial connexion was originally envisaged to connect a DTE (Data Terminal Equipment)
to a DCE (Data Circuit-terminating Equipment). The DCE (some sort of modem) would assert
the DTE's (the computer or terminal) DSR line to indicate it was ready. The DTE would
assert DTR to indicate to the DCE that it should attempt a connexion to the remote DCE.
Once a connexion was established the DCE would assert the DTE's CD pin. Data could then 
flow between the DTR and the remote DTE via the two DCEs. Flow control was provided
via the RTS and CTS lines. The DTE asserts RTS when it is capable of receiving new data,
and pauses its transmission of data when the CTS line is de-asserted. The local DCE
asserts CTS when the remote DCE detects RTS, and vice versa.
.PP
In modern usage the signals are slightly different, for a typical connexion using modems
DSR indicates that the modem is ready, a drop DTR is used to indicate to the
modem that it should break the connexion to the remote modem.  CD indicates that
the local modem is connected to the remote modem, and CTS and RTS behave as before. Connexion
is established by in-band signalling before CD is asserted.
.PP
For a \fBnull modem\fP cable local DSR and DTR are wired to remote CD, local
CTS to remote RTS, and local RTS to remote CTS. Thus asserting local DTR
asserts local DSR and remote CD, and asserting local RTS asserts remote CTS.
.PP
When RTS/CTS flow control is in operation and the receive buffer becomes full,
the operating system, or the hardware, de-asserts RTS, causing (via the DCEs or
the null modem cable) a de-assertion of remote CTS which in turn causes the
remote DTE to cease transmission.
.SH EXAMPLES
.PP 
using sympathy to mimic screen(1):
.IP
[foo@barhost ~]$ sympathy
.IP
.I Sympathy 
forks. The child becomes a daemon server and launches a new shell in a
pseudo-tty, the original process becomes a client and connects to the server
and shows the output. The user then uses the new shell and after some time
either hangs up on the client or issues CTRL\-B quit, and the client detaches from 
the server.
.IP
Later the user wishes to retrieve her session and to determine which sympathy
sessions are active and issues:
.IP
[foo@barhost ~]$ sympathy \-ls
.br
        barhost.2456        (Active)
.br
[root@barhost ~]$ 
.IP
The user then issues:
.IP
[foo@barhost ~]$ sympathy \-r 2456
.IP
and is reconnected to her session.
.PP
using sympathy to mimic minicom(1):
.IP
.IP
[foo@barhost ~]$ sympathy \-t \-d /dev/modem \-b 9600 \-K
.IP
.I Sympathy
opens the device /dev/modem and locks it, sets the baud\-rate to 9600 baud and disables
flow control. A VT102 terminal emulator then displays the data from the modem. The user
quits the emulator by issuing CTRL\-B quit, which unlocks the modem and exits sympathy.
.PP
using sympathy to mimic consolidate(1):
.IP
.IP
[foo@barhost ~]$ sympathy \-s \-d /dev/ttyS13 \-b 19200 \-K \-k /root/sympathy/13 \-L /root/sympathy/13.log
.IP
.I Sympathy
becomes a daemon and detaches from the current tty. It then opens the device
/dev/ttyS13 and locks it, sets the baud\-rate to 19200 baud and disables flow
control. 
.I Sympathy
then listens for clients connecting on the socket \fI/root/sympathy/13\fP, whilst logging 
completed lines and changes in status to the file \fI/root/sympathy/13.log\fP.
.IP
A user wishing to see the current status of /dev/ttyS13 issues:
.IP
[foo@barhost ~]$ sympathy \-c \-k /root/sympathy/13 
.IP
and the last 200 lines of history are injected into the history of her outer
terminal emulator and she is connected to /dev/ttyS13. The user disconnects from the
server by issuing CTRL\-B quit.
.SH SEE ALSO
screen(1) minicom(1) consolidate(1)
.SH STANDARDS
ANSI X3.64, ISO-6429, ECMA-48, ISO-2202, ISO-8859, ISO-10646, Digital Equipment Corp. VT102.
.SH BUGS
.PD
.IP \(bu 3
The command editor and parser should support better line editing.
.IP \(bu 3
It should be possible to change the escape character.
.IP \(bu 3
When the \-\fBc\fP \-\fBs\fP major mode is used without the \-\fBk\fP option the pid
used in the socket is that of the client process and therefore not unique.
.IP \(bu 3
The HTML generated with the \-\fBH\fP option is ugly.
.IP \(bu 3
No useful error message is generated if opening the terminal device fails in  the
\-\fBc\fP \-\fBs\fP major mode.
.IP \(bu 3
No facility is made for rotation of the log files.
.SH AUTHOR
James McKenzie, james@fishsoup.dhs.org