User Commands ZSHTCPSYS(1)
NAME
zshtcpsys - zsh tcp system
DESCRIPTION
A module zsh/net/tcp is provided to provide network I/O over
TCP/IP from within the shell; see its description in zshmo-
dules(1) . This manual page describes a function suitebased on the module. If the module is installed, the func-
tions are usually installed at the same time, in which casethey will be available for autoloading in the default func-
tion search path. In addition to the zsh/net/tcp module, the zsh/zselect module is used to implement timeouts on read operations. For troubleshooting tips, consult the corresponding advice for the zftp functions described in zshftpsys(1) .There are functions corresponding to the basic I/O opera-
tions open, close, read and send, named tcp_open etc., as
well as a function tcp_expect for pattern match analysis of
data read as input. The system makes it easy to receive data from and send data to multiple named sessions at once. In addition, it can be linked with the shell's line editor in such a way that input data is automatically shown at the terminal. Other facilities available including logging, filtering and configurable output prompts. To use the system where it is available, it should be enoughto `autoload -U tcp_open' and run tcp_open as documented
below to start a session. The tcp_open function will auto-
load the remaining functions. TCP USER FUNCTIONSBasic I/O
tcp_open [-qz] host port [ sess ]
tcp_open [-qz] [ -s sess | -l sess,... ] ...
tcp_open [-qz] [-a fd | -f fd ] [ sess ]
Open a new session. In the first and simplest form, open a TCP connection to host host at port port; numeric and symbolic forms are understood for both. If sess is given, this becomes the name of the session which can be used to refer to multiple different TCP connections. If sess is not given, the function will invent a numeric name value (note this is not the same as the file descriptor to which the session is attached). It is recommended that session names not include `funny' characters, where funny characters arenot well-defined but certainly do not include
alphanumerics or underscores, and certainly do include whitespace. zsh 4.3.10 Last change: June 1, 2009 1 User Commands ZSHTCPSYS(1) In the second case, one or more sessions to be opened are given by name. A single session name is givenafter -s and a comma-separated list after -l; both
options may be repeated as many times as necessary. Afailure to open any session causes tcp_open to abort.
The host and port are read from the file .ztcp_sessions
in the same directory as the user's zsh initialisationfiles, i.e. usually the home directory, but $ZDOTDIR if
that is set. The file consists of lines each giving a session name and the corresponding host and port, in that order (note the session name comes first, not last), separated by whitespace. The third form allows passive and fake TCP connections.If the option -a is used, its argument is a file
descriptor open for listening for connections. Nofunction front-end is provided to open such a file
descriptor, but a call to `ztcp -l port' will create
one with the file descriptor stored in the parameter$REPLY. The listening port can be closed with `ztcp -c
fd'. A call to `tcp_open -a fd' will block until a
remote TCP connection is made to port on the local machine. At this point, a session is created in the usual way and is largely indistinguishable from an active connection created with one of the first two forms.If the option -f is used, its argument is a file
descriptor which is used directly as if it were a TCP session. How well the remainder of the TCP functionsystem copes with this depends on what actually under-
lies this file descriptor. A regular file is likely to be unusable; a FIFO (pipe) of some sort will work better, but note that it is not a good idea for two different sessions to attempt to read from the same FIFO at once.If the option -q is given with any of the three forms,
tcp_open will not print informational messages,
although it will in any case exit with an appropriate status. If the line editor (zle) is in use, which is typicallythe case if the shell is interactive, tcp_open installs
a handler inside zle which will check for new data at the same time as it checks for keyboard input. This is convenient as the shell consumes no CPU time while waiting; the test is performed by the operating system.Giving the option -z to any of the forms of tcp_open
prevents the handler from being installed, so data mustbe read explicitly. Note, however, this is not neces-
sary for executing complete sets of send and read zsh 4.3.10 Last change: June 1, 2009 2 User Commands ZSHTCPSYS(1) commands from a function, as zle is not active at this point. Generally speaking, the handler is only active when the shell is waiting for input at a command prompt or in the vared builtin. The option has no effect ifzle is not active; `[[ -o zle]]' will test for this.
The first session to be opened becomes the current ses-
sion and subsequent calls to tcp_open do not change it.
The current session is stored in the parameter$TCP_SESS; see below for more detail about the parame-
ters used by the system.The function tcp_on_open, if defined, is called when a
session is opened. See the description below.tcp_close [-qn] [ -a | -l sess,... | sess ... ]
Close the named sessions, or the current session ifnone is given, or all open sessions if -a is given.
The options -l and -s are both handled for consistency
with tcp_open, although the latter is redundant.
If the session being closed is the current one,$TCP_SESS is unset, leaving no current session, even if
there are other sessions still open.If the session was opened with tcp_open -f, the file
descriptor is closed so long as it is in the range 0 to 9 accessible directly from the command line. If theoption -n is given, no attempt will be made to close
file descriptors in this case. The -n option is not
used for genuine ztcp session; the file descriptors are always closed with the session.If the option -q is given, no informational messages
will be printed.tcp_read [-bdq] [ -t TO ] [ -T TO ]
[ -a | -u fd ... | -l sess,... | -s sess ...]
Perform a read operation on the current session, or ona list of sessions if any are given with -u, -l or -s,
or all open sessions if the option -a is given. Any of
the -u, -l or -s options may be repeated or mixed
together. The -u option specifies a file descriptor
directly (only those managed by this system are use-
ful), the other two specify sessions as described fortcp_open above.
The function checks for new data available on all thesessions listed. Unless the -b option is given, it
will not block waiting for new data. Any one line of data from any of the available sessions will be read,stored in the parameter $TCP_LINE, and displayed to
zsh 4.3.10 Last change: June 1, 2009 3 User Commands ZSHTCPSYS(1)standard output unless $TCP_SILENT contains a non-empty
string. When printed to standard output the string$TCP_PROMPT will be shown at the start of the line; the
default form for this includes the name of the session being read. See below for more information on theseparameters. In this mode, tcp_read can be called
repeatedly until it returns status 2 which indicates all pending input from all specified sessions has been handled.With the option -b, equivalent to an infinite timeout,
the function will block until a line is available to read from one of the specified sessions. However, only a single line is returned.The option -d indicates that all pending input should
be drained. In this case tcp_read may process multiple
lines in the manner given above; only the last isstored in $TCP_LINE, but the complete set is stored in
the array $tcp_lines. This is cleared at the start of
each call to tcp_read.
The options -t and -T specify a timeout in seconds,
which may be a floating point number for increasedaccuracy. With -t the timeout is applied before each
line read. With -T, the timeout applies to the overall
operation, possibly including multiple read operationsif the option -d is present; without this option, there
is no distinction between -t and -T.
The function does not print informational messages, butif the option -q is given, no error message is printed
for a non-existent session.
A return status of 2 indicates a timeout or no data toread. Any other non-zero return status indicates some
error condition.See tcp_log for how to control where data is sent by
tcp_read.
tcp_send [-cnq] [ -s sess | -l sess,... ] data ...
tcp_send [-cnq] -a data ...
Send the supplied data strings to all the specified sessions in turn. The underlying operation differslittle from a `print -r' to the session's file descrip-
tor, although it attempts to prevent the shell from dying owing to a SIGPIPE caused by an attempt to write to a defunct session.The option -c causes tcp_send to behave like cat. It
reads lines from standard input until end of input and zsh 4.3.10 Last change: June 1, 2009 4 User Commands ZSHTCPSYS(1) sends them in turn to the specified session(s) exactly as if they were given as data arguments to individualtcp_send commands.
The option -n prevents tcp_send from putting a newline
at the end of the data strings.The remaining options all behave as for tcp_read.
The data arguments are not further processed once theyhave been passed to tcp_send; they are simply passed
down to print -r.
If the parameter $TCP_OUTPUT is a non-empty string and
logging is enabled then the data sent to each sessionwill be echoed to the log file(s) with $TCP_OUTPUT in
front where appropriate, much in the manner of$TCP_PROMPT.
Session Managementtcp_alias [-q] alias=sess ...
tcp_alias [-q] [ alias ] ...
tcp_alias -d [-q] alias ...
This function is not particularly well tested. The first form creates an alias for a session name; alias can then be used to refer to the existing session sess. As many aliases may be listed as required. The second form lists any aliases specified, or all aliases if none. The third form deletes all the aliases listed. The underlying sessions are not affected.The option -q suppresses an inconsistently chosen sub-
set of error messages.tcp_log [-asc] [ -n | -N ] [ logfile ]
With an argument logfile, all future input fromtcp_read will be logged to the named file. Unless -a
(append) is given, this file will first be truncated or created empty. With no arguments, show the current status of logging.With the option -s, per-session logging is enabled.
Input from tcp_read is output to the file logfile.sess.
As the session is automatically discriminated by thefilename, the contents are raw (no $TCP_PROMPT). The
option -a applies as above. Per-session logging and
logging of all data in one file are not mutually exclusive. zsh 4.3.10 Last change: June 1, 2009 5 User Commands ZSHTCPSYS(1)The option -c closes all logging, both complete and
per-session logs.
The options -n and -N respectively turn off or restore
output of data read by tcp_read to standard output;
hence `tcp_log -cn' turns off all output by tcp_read.
The function is purely a convenient front end to set-
ting the parameters $TCP_LOG, $TCP_LOG_SESS,
$TCP_SILENT, which are described below.
tcp_rename old new
Rename session old to session new. The old name becomes invalid.tcp_sess [ sess [ command ... ] ]
With no arguments, list all the open sessions and asso-
ciated file descriptors. The current session is marked with a star. For use in functions, direct access tothe parameters $tcp_by_name, $tcp_by_fd and $TCP_SESS
is probably more convenient; see below. With a sess argument, set the current session to sess.This is equivalent to changing $TCP_SESS directly.
With additional arguments, temporarily set the current session while executing the string command .... Thefirst argument is re-evaluated so as to expand aliases
etc., but the remaining arguments are passed through asthe appear to tcp_sess. The original session is
restored when tcp_sess exits.
Advanced I/O
tcp_command send-options ... send-arguments ...
This is a convenient front-end to tcp_send. All argu-
ments are passed to tcp_send, then the function pauses
waiting for data. While data is arriving at leastevery $TCP_TIMEOUT (default 0.3) seconds, data is han-
dled and printed out according to the current settings. Status 0 is always returned. This is generally only useful for interactive use, to prevent the display becoming fragmented by output returned from the connection. Within a programme or function it is generally better to handle reading data by a more explicit method.tcp_expect [ -q ] [ -p var ] [ -t to | -T TO]
[ -a | -s sess ... | -l sess,... ] pattern ...
Wait for input matching any of the given patterns from any of the specified sessions. Input is ignored until an input line matches one of the given patterns; at zsh 4.3.10 Last change: June 1, 2009 6 User Commands ZSHTCPSYS(1) this point status zero is returned, the matching lineis stored in $TCP_LINE, and the full set of lines read
during the call to tcp_expect is stored in the array
$tcp_expect_lines.
Sessions are specified in the same way as tcp_read: the
default is to use the current session, otherwise thesessions specified by -a, -s, or -l are used.
Each pattern is a standard zsh extended-globbing pat-
tern; note that it needs to be quoted to avoid it being expanded immediately by filename generation. It must match the full line, so to match a substring there must be a `*' at the start and end. The line matchedagainst includes the $TCP_PROMPT added by tcp_read. It
is possible to include the globbing flags `#b' or `#m'
in the patterns to make backreferences available in theparameters $MATCH, $match, etc., as described in the
base zsh documentation on pattern matching.Unlike tcp_read, the default behaviour of tcp_expect is
to block indefinitely until the required input is found. This can be modified by specifying a timeoutwith -t or -T; these function as in tcp_read, specify-
ing a per-read or overall timeout, respectively, in
seconds, as an integer or floating-point number. As
tcp_read, the function returns status 2 if a timeout
occurs. The function returns as soon as any one of the patterns given match. If the caller needs to know which of thepatterns matched, the option -p var can be used; on
return, $var is set to the number of the pattern using
ordinary zsh indexing, i.e. the first is 1, and so on.Note the absence of a `$' in front of var. To avoid
clashes, the parameter cannot begin with `_expect'.
The option -q is passed directly down to tcp_read.
As all input is done via tcp_read, all the usual rules
about output of lines read apply. One exception isthat the parameter $tcp_lines will only reflect the
line actually matched by tcp_expect; use
$tcp_expect_lines for the full set of lines read during
the function call.tcp_proxy
This is a simple-minded function to accept a TCP con-
nection and execute a command with I/O redirected to the connection. Extreme caution should be taken as there is no security whatsoever and this can leave your computer open to the world. Ideally, it should only be zsh 4.3.10 Last change: June 1, 2009 7 User Commands ZSHTCPSYS(1) used behind a firewall. The first argument is a TCP port on which the function will listen.
The remaining arguments give a command and its argu-
ments to execute with standard input, standard output and standard error redirected to the file descriptor on which the TCP session has been accepted. If no command is given, a new zsh is started. This gives everyone on your network direct access to your account, which in many cases will be a bad thing.The command is run in the background, so tcp_proxy can
then accept new connections. It continues to accept new connections until interrupted.tcp_spam [-ertv] [ -a | -s sess | -l sess,... ] cmd ...
Execute `cmd ...' for each session in turn. Note this executes the command and arguments; it does not sendthe command line as data unless the -t (transmit)
option is given.The sessions may be selected explicitly with the stan-
dard -a, -s or -l options, or may be chosen implicitly.
If none of the three options is given the rules are:first, if the array $tcp_spam_list is set, this is
taken as the list of sessions, otherwise all sessions are taken. Second, any sessions given in the array$tcp_no_spam_list are removed from the list of ses-
sions.Normally, any sessions added by the `-a' flag or when
all sessions are chosen implicitly are spammed inalphabetic order; sessions given by the $tcp_spam_list
array or on the command line are spammed in the ordergiven. The -r flag reverses the order however it was
arrived it.The -v flag specifies that a $TCP_PROMPT will be output
before each session. This is output after any modifi-
cation to TCP_SESS by the user-defined tcp_on_spam
function described below. (Obviously that function is able to generate its own output.)If the option -e is present, the line given as cmd ...
is executed using eval, otherwise it is executed without any further processing.tcp_talk
This is a fairly simple-minded attempt to force input
to the line editor to go straight to the default zsh 4.3.10 Last change: June 1, 2009 8 User Commands ZSHTCPSYS(1)TCP_SESSION.
An escape string, $TCP_TALK_ESCAPE, default `:', is
used to allow access to normal shell operation. If it is on its own at the start of the line, or followed only by whitespace, the line editor returns to normal operation. Otherwise, the string and any following whitespace are skipped and the remainder of the line executed as shell input without any change of the line editor's operating mode. The current implementation is somewhat deficient in terms of use of the command history. For this reason, many users will prefer to use some form of alternativeapproach for sending data easily to the current ses-
sion. One simple approach is to alias some specialcharacter (such as `%') to `tcp_command --'.
tcp_wait
The sole argument is an integer or floating point number which gives the seconds to delay. The shell will do nothing for that period except wait for inputon all TCP sessions by calling tcp_read -a. This is
similar to the interactive behaviour at the command prompt when zle handlers are installed.`One-shot' file transfer
tcp_point port
tcp_shoot host port
This pair of functions provide a simple way to transfera file between two hosts within the shell. Note, how-
ever, that bulk data transfer is currently done usingcat. tcp_point reads any data arriving at port and
sends it to standard output; tcp_shoot connects to port
on host and sends its standard input. Any unused port may be used; the standard mechanism for picking a portis to think of a random four-digit number above 1024
until one works. To transfer a file from host woodcock to host springes, on springes:tcp_point 8091 >output_file
and on woodcock:tcp_shoot springes 8091
As these two functions do not require tcp_open to set
up a TCP connection first, they may need to be auto-
loaded separately. zsh 4.3.10 Last change: June 1, 2009 9 User Commands ZSHTCPSYS(1)TCP USER-DEFINED FUNCTIONS
Certain functions, if defined by the user, will be called by the function system in certain contexts. This facilitydepends on the module zsh/parameter, which is usually avail-
able in interactive shells as the completion system depends on it. None of the functions need be defined; they simply provide convenient hooks when necessary. Typically, these are called after the requested action has been taken, so that the various parameters will reflect the new state.tcp_on_alias alias fd
When an alias is defined, this function will be called with two arguments: the name of the alias, and the file descriptor of the corresponding session.tcp_on_awol sess fd
If the function tcp_fd_handler is handling input from
the line editor and detects that the file descriptor is no longer reusable, by default it removes it from the list of file descriptors handled by this method andprints a message. If the function tcp_on_awol is
defined it is called immediately before this point. It may return status 100, which indicates that the normal handling should still be performed; any other return status indicates that no further action should be takenand the tcp_fd_handler should return immediately with
the given status. Typically the action of tcp_on_awol
will be to close the session.The variable TCP_INVALIDATE_ZLE will be a non-empty
string if it is necessary to invalidate the line editordisplay using `zle -I' before printing output from the
function. (`AWOL' is military jargon for `absent without leave'or some variation. It has no pre-existing technical
meaning known to the author.)tcp_on_close sess fd
This is called with the name of a session being closedand the file descriptor which corresponded to that ses-
sion. Both will be invalid by the time the function is called.tcp_on_open sess fd
This is called after a new session has been defined with the session name and file descriptor as arguments.If it returns a non-zero status, opening the session is
assumed to fail and the session is closed again; how-
ever, tcp_open will continue to attempt to open any
zsh 4.3.10 Last change: June 1, 2009 10 User Commands ZSHTCPSYS(1) remaining sessions given on the command line.tcp_on_rename oldsess fd newsess
This is called after a session has been renamed with the three arguments old session name, file descriptor, new session name.tcp_on_spam sess command ...
This is called once for each session spammed, justbefore a command is executed for a session by tcp_spam.
The arguments are the session name followed by the com-
mand list to be executed. If tcp_spam was called with
the option -t, the first command will be tcp_send.
This function is called after $TCP_SESS is set to
reflect the session to be spammed, but before any use of it is made. Hence it is possible to alter the valueof $TCP_SESS within this function. For example, the
session arguments to tcp_spam could include extra
information to be stripped off and processed intcp_on_spam.
If the function sets the parameter $REPLY to `done',
the command line is not executed; in addition, noprompt is printed for the -v option to tcp_spam.
tcp_on_unalias alias fd
This is called with the name of an alias and the corresponding session's file descriptor after an alias has been deleted. TCP UTILITY FUNCTIONS The following functions are used by the TCP function system but will rarely if ever need to be called directly.tcp_fd_handler
This is the function installed by tcp_open for handling
input from within the line editor, if that is required.It is in the format documented for the builtin `zle -F'
in zshzle(1) . While active, the function sets the parameterTCP_HANDLER_ACTIVE to 1. This allows shell code called
internally (for example, by setting tcp_on_read) to
tell if is being called when the shell is otherwise idle at the editor prompt.tcp_output [ -q ] -P prompt -F fd -S sess
This function is used for both logging and handlingoutput to standard output, from within tcp_read and (if
$TCP_OUTPUT is set) tcp_send.
zsh 4.3.10 Last change: June 1, 2009 11 User Commands ZSHTCPSYS(1)The prompt to use is specified by -P; the default is
the empty string. It can contain:%c Expands to 1 if the session is the current ses-
sion, otherwise 0. Used with ternary expressionssuch as `%(c.-.+)' to output `+' for the current
session and `-' otherwise.
%f Replaced by the session's file descriptor.
%s Replaced by the session name.
%% Replaced by a single `%'.
The option -q suppresses output to standard output, but
not to any log files which are configured.The -S and -F options are used to pass in the session
name and file descriptor for possible replacement in the prompt.TCP USER PARAMETERS
Parameters follow the usual convention that uppercase is used for scalars and integers, while lowercase is used for normal and associative array. It is always safe for user code to read these parameters. Some parameters may also be set; these are noted explicitly. Others are included in this group as they are set by the function system for the user's benefit, i.e. setting them is typically not useful but is benign. It is often also useful to make settable parameters local toa function. For example, `local TCP_SILENT=1' specifies
that data read during the function call will not be printed to standard output, regardless of the setting outside thefunction. Likewise, `local TCP_SESS=sess' sets a session
for the duration of a function, and `local TCP_PROMPT='
specifies that no prompt is used for input during the func-
tion.tcp_expect_lines
Array. The set of lines read during the last call totcp_expect, including the last ($TCP_LINE).
tcp_filter
Array. May be set directly. A set of extended globbingpatterns which, if matched in tcp_output, will cause
the line not to be printed to standard output. Thepatterns should be defined as described for the argu-
ments to tcp_expect. Output of line to log files is
not affected.TCP_HANDLER_ACTIVE
zsh 4.3.10 Last change: June 1, 2009 12 User Commands ZSHTCPSYS(1)Scalar. Set to 1 within tcp_fd_handler to indicate to
functions called recursively that they have been called during an editor session. Otherwise unset.TCP_LINE
The last line read by tcp_read, and hence also
tcp_expect.
TCP_LINE_FD
The file descriptor from which $TCP_LINE was read.
${tcp_by_fd[$TCP_LINE_FD]} will give the corresponding
session name.tcp_lines
Array. The set of lines read during the last call totcp_read, including the last ($TCP_LINE).
TCP_LOG
May be set directly, although it is also controlled bytcp_log. The name of a file to which output from all
sessions will be sent. The output is proceeded by theusual $TCP_PROMPT. If it is not an absolute path name,
it will follow the user's current directory.TCP_LOG_SESS
May be set directly, although it is also controlled bytcp_log. The prefix for a set of files to which output
from each session separately will be sent; the fullfilename is ${TCP_LOG_SESS}.sess. Output to each file
is raw; no prompt is added. If it is not an absolute path name, it will follow the user's current directory.tcp_no_spam_list
Array. May be set directly. See tcp_spam for how this
is used.TCP_OUTPUT
May be set directly. If a non-empty string, any data
sent to a session by tcp_send will be logged. This
parameter gives the prompt to be used in a file speci-
fied by $TCP_LOG but not in a file generated from
$TCP_LOG_SESS. The prompt string has the same format
as TCP_PROMPT and the same rules for its use apply.
TCP_PROMPT
May be set directly. Used as the prefix for data readby tcp_read which is printed to standard output or to
the log file given by $TCP_LOG, if any. Any `%s', `%f'
or `%%' occurring in the string will be replaced by the
name of the session, the session's underlying filedescriptor, or a single `%', respectively. The expres-
sion `%c' expands to 1 if the session being read is the
zsh 4.3.10 Last change: June 1, 2009 13 User Commands ZSHTCPSYS(1) current session, else 0; this is most useful in ternaryexpressions such as `%(c.-.+)' which outputs `+' if the
session is the current one, else `-'.
TCP_READ_DEBUG
May be set directly. If this has non-zero length,
tcp_read will give some limited diagnostics about data
being read.TCP_SECONDS_START
This value is created and initialised to zero bytcp_open.
The functions tcp_read and tcp_expect use the shell's
SECONDS parameter for their own timing purposes. If that parameter is not of floating point type on entryto one of the functions, it will create a local parame-
ter SECONDS which is floating point and set the parame-
ter TCP_SECONDS_START to the previous value of
$SECONDS. If the parameter is already floating point,
it is used without a local copy being created andTCP_SECONDS_START is not set. As the global value is
zero, the shell elapsed time is guaranteed to be thesum of $SECONDS and $TCP_SECONDS_START.
This can be avoided by setting SECONDS globally to afloating point value using `typeset -F SECONDS'; then
the TCP functions will never make a local copy andnever set TCP_SECONDS_START to a non-zero value.
TCP_SESS
May be set directly. The current session; must referto one of the sessions established by tcp_open.
TCP_SILENT
May be set directly, although it is also controlled bytcp_log. If of non-zero length, data read by tcp_read
will not be written to standard output, though may still be written to a log file.tcp_spam_list
Array. May be set directly. See the description ofthe function tcp_spam for how this is used.
TCP_TALK_ESCAPE
May be set directly. See the description of the func-
tion tcp_talk for how this is used.
TCP_TIMEOUT
May be set directly. Currently this is only used bythe function tcp_command, see above.
zsh 4.3.10 Last change: June 1, 2009 14 User Commands ZSHTCPSYS(1)TCP USER-DEFINED PARAMETERS
The following parameters are not set by the function system, but have a special effect if set by the user.tcp_on_read
This should be an associative array; if it is not, the behaviour is undefined. Each key is the name of a shell function or other command, and the correspondingvalue is a shell pattern (using EXTENDED_GLOB). Every
line read from a TCP session directly or indirectlyusing tcp_read (which includes lines read by
tcp_expect) is compared against the pattern. If the
line matches, the command given in the key is called with two arguments: the name of the session from which the line was read, and the line itself. If any function called to handle a line returns anon-zero status, the line is not output. Thus a
tcp_on_read handler containing only the instruction
`return 1' can be used to suppress output of particularlines (see, however, tcp_filter above). However, the
line is still stored in TCP_LINE and tcp_lines; this
occurs after all tcp_on_read processing.
TCP UTILITY PARAMETERS
These parameters are controlled by the function system; they may be read directly, but should not usually be set by user code.tcp_aliases
Associative array. The keys are the names of sessionsestablished with tcp_open; each value is a
space-separated list of aliases which refer to that
session.tcp_by_fd
Associative array. The keys are session file descrip-
tors; each value is the name of that session.tcp_by_name
Associative array. The keys are the names of sessions; each value is the file descriptor associated with that session.TCP EXAMPLES
Here is a trivial example using a remote calculator. TO create a calculator server on port 7337 (see the dc manual page for quite how infuriating the underlying command is): zsh 4.3.10 Last change: June 1, 2009 15 User Commands ZSHTCPSYS(1)tcp_proxy 7337 dc
To connect to this from the same host with a session also named `dc':tcp_open localhost 7337 dc
To send a command to the remote session and wait a short while for output (assuming dc is the current session):tcp_command 2 4 + p
To close the session:tcp_close
The tcp_proxy needs to be killed to be stopped. Note this
will not usually kill any connections which have already been accepted, and also that the port is not immediately available for reuse. The following chunk of code puts a list of sessions into an xterm header, with the current session followed by a star.print -n "\033]2;TCP:" ${(k)tcp_by_name:/$TCP_SESS/$TCP_SESS\*} "\a"
TCP BUGS
The function tcp_read uses the shell's normal read builtin.
As this reads a complete line at once, data arriving withouta terminating newline can cause the function to block inde-
finitely. Though the function suite works well for interactive use and for data arriving in small amounts, the performance when large amounts of data are being exchanged is likely to be extremely poor.ATTRIBUTES
See attributes(5) for descriptions of the following attri-
butes: zsh 4.3.10 Last change: June 1, 2009 16 User Commands ZSHTCPSYS(1)_______________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE|
|____________________|__________________|_
| Availability | shell/zsh ||____________________|__________________|_
| Interface Stability| External ||____________________|_________________|
NOTES Source for zsh is available on http://opensolaris.org. zsh 4.3.10 Last change: June 1, 2009 17