1ZSHTCPSYS(1)                General Commands Manual               ZSHTCPSYS(1)
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3
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NAME

6       zshtcpsys - zsh tcp system
7

DESCRIPTION

9       A  module  zsh/net/tcp  is  provided to provide network I/O over TCP/IP
10       from within the shell; see its description  in  zshmodules(1)  .   This
11       manual  page  describes  a  function suite based on the module.  If the
12       module is installed, the functions are usually installed  at  the  same
13       time,  in  which  case  they  will  be available for autoloading in the
14       default function search path.  In addition to the  zsh/net/tcp  module,
15       the  zsh/zselect  module  is  used to implement timeouts on read opera‐
16       tions.  For troubleshooting tips, consult the corresponding advice  for
17       the zftp functions described in zshftpsys(1) .
18
19       There  are  functions  corresponding  to the basic I/O operations open,
20       close, read and send, named  tcp_open  etc.,  as  well  as  a  function
21       tcp_expect  for pattern match analysis of data read as input.  The sys‐
22       tem makes it easy to receive data from and send data to multiple  named
23       sessions  at once.  In addition, it can be linked with the shell's line
24       editor in such a way that input data is automatically shown at the ter‐
25       minal.   Other  facilities  available  including logging, filtering and
26       configurable output prompts.
27
28       To use the system where  it  is  available,  it  should  be  enough  to
29       `autoload  -U tcp_open' and run tcp_open as documented below to start a
30       session.  The tcp_open function will autoload the remaining functions.
31

TCP USER FUNCTIONS

33   Basic I/O
34       tcp_open [-qz] host port [ sess ]
35       tcp_open [-qz] [ -s sess | -l sess,... ] ...
36       tcp_open [-qz] [-a fd | -f fd ] [ sess ]
37              Open a new session.  In the first and simplest form, open a  TCP
38              connection to host host at port port; numeric and symbolic forms
39              are understood for both.
40
41              If sess is given, this becomes the name of the session which can
42              be used to refer to multiple different TCP connections.  If sess
43              is not given, the function will  invent  a  numeric  name  value
44              (note  this  is not the same as the file descriptor to which the
45              session is attached).  It is recommended that session names  not
46              include  `funny'  characters,  where  funny  characters  are not
47              well-defined but  certainly  do  not  include  alphanumerics  or
48              underscores, and certainly do include whitespace.
49
50              In  the second case, one or more sessions to be opened are given
51              by name.  A  single  session  name  is  given  after  -s  and  a
52              comma-separated  list  after -l; both options may be repeated as
53              many times as necessary.  A failure to open any  session  causes
54              tcp_open  to  abort.   The  host and port are read from the file
55              .ztcp_sessions in the same directory as the user's zsh initiali‐
56              sation  files,  i.e. usually the home directory, but $ZDOTDIR if
57              that is set.  The file consists of lines each giving  a  session
58              name  and  the  corresponding host and port, in that order (note
59              the session name comes first, not  last),  separated  by  white‐
60              space.
61
62              The  third form allows passive and fake TCP connections.  If the
63              option -a is used, its argument is a file  descriptor  open  for
64              listening for connections.  No function front-end is provided to
65              open such a file descriptor, but a call to `ztcp -l  port'  will
66              create  one  with  the  file  descriptor stored in the parameter
67              $REPLY.  The listening port can be closed with `ztcp -c fd'.   A
68              call  to  `tcp_open -a fd' will block until a remote TCP connec‐
69              tion is made to port on the local machine.   At  this  point,  a
70              session  is  created  in  the usual way and is largely indistin‐
71              guishable from an active connection  created  with  one  of  the
72              first two forms.
73
74              If  the  option  -f  is  used, its argument is a file descriptor
75              which is used directly as if it were a TCP  session.   How  well
76              the remainder of the TCP function system copes with this depends
77              on what actually underlies this file descriptor.  A regular file
78              is  likely  to be unusable; a FIFO (pipe) of some sort will work
79              better, but note that it is not a good idea  for  two  different
80              sessions to attempt to read from the same FIFO at once.
81
82              If  the option -q is given with any of the three forms, tcp_open
83              will not print informational messages, although it will  in  any
84              case exit with an appropriate status.
85
86              If  the line editor (zle) is in use, which is typically the case
87              if the shell is interactive, tcp_open installs a handler  inside
88              zle  which will check for new data at the same time as it checks
89              for keyboard input.  This is convenient as the shell consumes no
90              CPU  time  while waiting; the test is performed by the operating
91              system.  Giving the option -z to any of the  forms  of  tcp_open
92              prevents  the handler from being installed, so data must be read
93              explicitly.  Note, however, this is not necessary for  executing
94              complete  sets of send and read commands from a function, as zle
95              is not active at this point.  Generally speaking, the handler is
96              only  active  when  the  shell is waiting for input at a command
97              prompt or in the vared builtin.  The option has no effect if zle
98              is not active; `[[ -o zle]]' will test for this.
99
100              The  first  session to be opened becomes the current session and
101              subsequent calls to tcp_open do not change it.  The current ses‐
102              sion  is  stored  in the parameter $TCP_SESS; see below for more
103              detail about the parameters used by the system.
104
105              The function tcp_on_open, if defined, is called when  a  session
106              is opened.  See the description below.
107
108       tcp_close [-qn] [ -a | -l sess,... | sess ... ]
109              Close  the  named  sessions,  or  the current session if none is
110              given, or all open sessions if -a is given.  The options -l  and
111              -s  are both handled for consistency with tcp_open, although the
112              latter is redundant.
113
114              If the session being closed is the  current  one,  $TCP_SESS  is
115              unset,  leaving no current session, even if there are other ses‐
116              sions still open.
117
118              If the session was opened with tcp_open -f, the file  descriptor
119              is  closed  so  long  as  it  is  in the range 0 to 9 accessible
120              directly from the command line.  If the option -n is  given,  no
121              attempt  will  be  made  to close file descriptors in this case.
122              The -n option is not used for genuine  ztcp  session;  the  file
123              descriptors are always closed with the session.
124
125              If  the  option  -q  is given, no informational messages will be
126              printed.
127
128       tcp_read [-bdq] [ -t TO ] [ -T TO ]
129           [ -a | -u fd ... | -l sess,... | -s sess ...]
130              Perform a read operation on the current session, or on a list of
131              sessions  if  any  are given with -u, -l or -s, or all open ses‐
132              sions if the option -a is given.   Any  of  the  -u,  -l  or  -s
133              options may be repeated or mixed together.  The -u option speci‐
134              fies a file descriptor directly (only those managed by this sys‐
135              tem are useful), the other two specify sessions as described for
136              tcp_open above.
137
138              The function checks for new data available on all  the  sessions
139              listed.   Unless the -b option is given, it will not block wait‐
140              ing for new data.  Any one line of data from any of  the  avail‐
141              able  sessions  will be read, stored in the parameter $TCP_LINE,
142              and displayed to standard output unless $TCP_SILENT  contains  a
143              non-empty  string.   When  printed to standard output the string
144              $TCP_PROMPT will be shown at the start of the line; the  default
145              form  for this includes the name of the session being read.  See
146              below for more information on these parameters.  In  this  mode,
147              tcp_read  can  be  called  repeatedly  until it returns status 2
148              which indicates all pending input from  all  specified  sessions
149              has been handled.
150
151              With the option -b, equivalent to an infinite timeout, the func‐
152              tion will block until a line is available to read  from  one  of
153              the   specified  sessions.   However,  only  a  single  line  is
154              returned.
155
156              The option  -d  indicates  that  all  pending  input  should  be
157              drained.   In  this  case tcp_read may process multiple lines in
158              the manner given above; only the last is  stored  in  $TCP_LINE,
159              but the complete set is stored in the array $tcp_lines.  This is
160              cleared at the start of each call to tcp_read.
161
162              The options -t and -T specify a timeout in seconds, which may be
163              a  floating  point  number  for increased accuracy.  With -t the
164              timeout is applied before each line read.  With -T, the  timeout
165              applies  to  the  overall operation, possibly including multiple
166              read operations if  the  option  -d  is  present;  without  this
167              option, there is no distinction between -t and -T.
168
169              The  function  does not print informational messages, but if the
170              option -q is given, no error message is printed for a  non-exis‐
171              tent session.
172
173              A  return  status  of  2 indicates a timeout or no data to read.
174              Any other non-zero return status indicates some error condition.
175
176              See tcp_log for how to control where data is sent by tcp_read.
177
178       tcp_send [-cnq] [ -s sess | -l sess,... ] data ...
179       tcp_send [-cnq] -a data ...
180              Send the supplied data strings to all the specified sessions  in
181              turn.  The underlying operation differs little from a `print -r'
182              to the session's file descriptor, although it attempts  to  pre‐
183              vent  the  shell  from  dying  owing  to  a SIGPIPE caused by an
184              attempt to write to a defunct session.
185
186              The option -c causes tcp_send to  behave  like  cat.   It  reads
187              lines  from  standard input until end of input and sends them in
188              turn to the specified session(s) exactly as if they  were  given
189              as data arguments to individual tcp_send commands.
190
191              The  option  -n  prevents tcp_send from putting a newline at the
192              end of the data strings.
193
194              The remaining options all behave as for tcp_read.
195
196              The data arguments are not further processed once they have been
197              passed to tcp_send; they are simply passed down to print -r.
198
199              If  the  parameter $TCP_OUTPUT is a non-empty string and logging
200              is enabled then the data sent to each session will be echoed  to
201              the  log  file(s)  with  $TCP_OUTPUT in front where appropriate,
202              much in the manner of $TCP_PROMPT.
203
204   Session Management
205       tcp_alias [-q] alias=sess ...
206       tcp_alias [-q] [ alias ] ...
207       tcp_alias -d [-q] alias ...
208              This function is not particularly well tested.
209
210              The first form creates an alias for a session  name;  alias  can
211              then  be  used  to  refer to the existing session sess.  As many
212              aliases may be listed as required.
213
214              The second form lists any aliases specified, or all  aliases  if
215              none.
216
217              The  third  form deletes all the aliases listed.  The underlying
218              sessions are not affected.
219
220              The option -q suppresses  an  inconsistently  chosen  subset  of
221              error messages.
222
223       tcp_log [-asc] [ -n | -N ] [ logfile ]
224              With an argument logfile, all future input from tcp_read will be
225              logged to the named file.  Unless -a  (append)  is  given,  this
226              file  will  first  be truncated or created empty.  With no argu‐
227              ments, show the current status of logging.
228
229              With the option -s, per-session logging is enabled.  Input  from
230              tcp_read  is output to the file logfile.sess.  As the session is
231              automatically discriminated by the filename,  the  contents  are
232              raw   (no  $TCP_PROMPT).   The  option   -a  applies  as  above.
233              Per-session logging and logging of all data in one file are  not
234              mutually exclusive.
235
236              The  option -c closes all logging, both complete and per-session
237              logs.
238
239              The options -n and -N respectively turn off or restore output of
240              data  read  by  tcp_read to standard output; hence `tcp_log -cn'
241              turns off all output by tcp_read.
242
243              The function is purely a convenient front  end  to  setting  the
244              parameters   $TCP_LOG,  $TCP_LOG_SESS,  $TCP_SILENT,  which  are
245              described below.
246
247       tcp_rename old new
248              Rename session  old  to  session  new.   The  old  name  becomes
249              invalid.
250
251       tcp_sess [ sess [ command  ... ] ]
252              With  no  arguments,  list  all the open sessions and associated
253              file descriptors.  The current session is marked  with  a  star.
254              For   use   in   functions,  direct  access  to  the  parameters
255              $tcp_by_name, $tcp_by_fd and $TCP_SESS is probably  more  conve‐
256              nient; see below.
257
258              With  a sess argument, set the current session to sess.  This is
259              equivalent to changing $TCP_SESS directly.
260
261              With additional arguments, temporarily set the  current  session
262              while  executing  the string command ....  The first argument is
263              re-evaluated so as to expand aliases  etc.,  but  the  remaining
264              arguments  are  passed  through  as the appear to tcp_sess.  The
265              original session is restored when tcp_sess exits.
266
267   Advanced I/O
268       tcp_command send-options ... send-arguments ...
269              This is a convenient front-end to tcp_send.  All  arguments  are
270              passed  to  tcp_send, then the function pauses waiting for data.
271              While data is arriving at least every $TCP_TIMEOUT (default 0.3)
272              seconds,  data  is handled and printed out according to the cur‐
273              rent settings.  Status 0 is always returned.
274
275              This is generally only useful for interactive  use,  to  prevent
276              the display becoming fragmented by output returned from the con‐
277              nection.  Within a programme or function it is generally  better
278              to handle reading data by a more explicit method.
279
280       tcp_expect [ -q ] [ -p var ] [ -t  to | -T TO]
281           [ -a | -s sess ... | -l sess,... ] pattern ...
282              Wait  for  input  matching any of the given patterns from any of
283              the specified sessions.  Input is ignored until  an  input  line
284              matches  one of the given patterns; at this point status zero is
285              returned, the matching line is stored in $TCP_LINE, and the full
286              set of lines read during the call to tcp_expect is stored in the
287              array $tcp_expect_lines.
288
289              Sessions are specified in the same way as tcp_read: the  default
290              is  to use the current session, otherwise the sessions specified
291              by -a, -s, or -l are used.
292
293              Each pattern is a standard zsh extended-globbing  pattern;  note
294              that  it  needs  to be quoted to avoid it being expanded immedi‐
295              ately by filename generation.  It must match the full  line,  so
296              to  match  a substring there must be a `*' at the start and end.
297              The line matched  against  includes  the  $TCP_PROMPT  added  by
298              tcp_read.   It is possible to include the globbing flags `#b' or
299              `#m' in the patterns to make  backreferences  available  in  the
300              parameters  $MATCH,  $match,  etc., as described in the base zsh
301              documentation on pattern matching.
302
303              Unlike tcp_read, the default behaviour of tcp_expect is to block
304              indefinitely  until  the  required  input is found.  This can be
305              modified by specifying a timeout with -t or -T;  these  function
306              as  in  tcp_read,  specifying  a  per-read  or  overall timeout,
307              respectively, in seconds, as an integer or  floating-point  num‐
308              ber.   As  tcp_read,  the function returns status 2 if a timeout
309              occurs.
310
311              The function returns as soon as any one of  the  patterns  given
312              match.   If  the  caller  needs  to  know  which of the patterns
313              matched, the option -p var can be used; on return, $var  is  set
314              to  the  number of the pattern using ordinary zsh indexing, i.e.
315              the first is 1, and so on.  Note the absence of a `$'  in  front
316              of  var.   To  avoid  clashes,  the  parameter cannot begin with
317              `_expect'.
318
319              The option -q is passed directly down to tcp_read.
320
321              As all input is done via tcp_read, all  the  usual  rules  about
322              output of lines read apply.  One exception is that the parameter
323              $tcp_lines will  only  reflect  the  line  actually  matched  by
324              tcp_expect; use $tcp_expect_lines for the full set of lines read
325              during the function call.
326
327       tcp_proxy
328              This is a simple-minded function to accept a TCP connection  and
329              execute  a  command  with  I/O  redirected  to  the  connection.
330              Extreme caution should be taken as there is no security  whatso‐
331              ever  and  this can leave your computer open to the world.  Ide‐
332              ally, it should only be used behind a firewall.
333
334              The first argument is a TCP port on which the function will lis‐
335              ten.
336
337              The remaining arguments give a command and its arguments to exe‐
338              cute with standard input, standard  output  and  standard  error
339              redirected  to  the file descriptor on which the TCP session has
340              been accepted.  If no command is given, a new  zsh  is  started.
341              This  gives  everyone  on  your  network  direct  access to your
342              account, which in many cases will be a bad thing.
343
344              The command is run in the  background,  so  tcp_proxy  can  then
345              accept  new connections.  It continues to accept new connections
346              until interrupted.
347
348       tcp_spam [-ertv] [ -a | -s  sess | -l sess,... ] cmd ...
349              Execute `cmd ...' for each session in turn.  Note this  executes
350              the  command and arguments; it does not send the command line as
351              data unless the -t (transmit) option is given.
352
353              The sessions may be selected explicitly with the standard -a, -s
354              or  -l  options,  or  may  be chosen implicitly.  If none of the
355              three options is given  the  rules  are:  first,  if  the  array
356              $tcp_spam_list  is  set,  this is taken as the list of sessions,
357              otherwise all sessions are taken.  Second, any sessions given in
358              the  array  $tcp_no_spam_list  are removed from the list of ses‐
359              sions.
360
361              Normally, any sessions added by the `-a' flag or when  all  ses‐
362              sions  are  chosen  implicitly  are spammed in alphabetic order;
363              sessions given by the $tcp_spam_list array  or  on  the  command
364              line  are  spammed in the order given.  The -r flag reverses the
365              order however it was arrived it.
366
367              The -v flag specifies that a $TCP_PROMPT will be  output  before
368              each session.  This is output after any modification to TCP_SESS
369              by  the  user-defined  tcp_on_spam  function  described   below.
370              (Obviously that function is able to generate its own output.)
371
372              If  the  option -e is present, the line given as cmd ... is exe‐
373              cuted using eval, otherwise it is executed without  any  further
374              processing.
375
376       tcp_talk
377              This  is  a  fairly  simple-minded attempt to force input to the
378              line editor to go straight to the default TCP_SESSION.
379
380              An escape string, $TCP_TALK_ESCAPE,  default  `:',  is  used  to
381              allow  access to normal shell operation.  If it is on its own at
382              the start of the line, or followed only by whitespace, the  line
383              editor  returns  to normal operation.  Otherwise, the string and
384              any following whitespace are skipped and the  remainder  of  the
385              line executed as shell input without any change of the line edi‐
386              tor's operating mode.
387
388              The current implementation is somewhat deficient in terms of use
389              of the command history.  For this reason, many users will prefer
390              to use some form of alternative approach for sending data easily
391              to  the  current  session.  One simple approach is to alias some
392              special character (such as `%') to `tcp_command --'.
393
394       tcp_wait
395              The sole argument is an integer or floating point  number  which
396              gives  the seconds to delay.  The shell will do nothing for that
397              period except wait for input on  all  TCP  sessions  by  calling
398              tcp_read  -a.   This  is similar to the interactive behaviour at
399              the command prompt when zle handlers are installed.
400
401   `One-shot' file transfer
402       tcp_point port
403       tcp_shoot host port
404              This pair of functions provide a simple way to transfer  a  file
405              between  two  hosts  within the shell.  Note, however, that bulk
406              data transfer is currently done using cat.  tcp_point reads  any
407              data arriving at port and sends it to standard output; tcp_shoot
408              connects to port on host and  sends  its  standard  input.   Any
409              unused  port  may  be used; the standard mechanism for picking a
410              port is to think of a random four-digit number above 1024  until
411              one works.
412
413              To  transfer  a  file  from  host  woodcock to host springes, on
414              springes:
415
416                     tcp_point 8091 >output_file
417
418              and on woodcock:
419
420                     tcp_shoot springes 8091 <input_file
421
422              As these two functions do not require tcp_open to set up  a  TCP
423              connection first, they may need to be autoloaded separately.
424

TCP USER-DEFINED FUNCTIONS

426       Certain  functions, if defined by the user, will be called by the func‐
427       tion system in certain contexts.  This facility depends on  the  module
428       zsh/parameter,  which is usually available in interactive shells as the
429       completion system depends  on  it.   None  of  the  functions  need  be
430       defined; they simply provide convenient hooks when necessary.
431
432       Typically,  these are called after the requested action has been taken,
433       so that the various parameters will reflect the new state.
434
435       tcp_on_alias alias fd
436              When an alias is defined, this function will be called with  two
437              arguments: the name of the alias, and the file descriptor of the
438              corresponding session.
439
440       tcp_on_awol sess fd
441              If the function tcp_fd_handler is handling input from  the  line
442              editor  and  detects that the file descriptor is no longer reus‐
443              able, by default it removes it from the list of file descriptors
444              handled  by  this  method and prints a message.  If the function
445              tcp_on_awol is defined it  is  called  immediately  before  this
446              point.   It may return status 100, which indicates that the nor‐
447              mal handling should still be performed; any other return  status
448              indicates  that  no  further  action  should  be  taken  and the
449              tcp_fd_handler should return immediately with the given  status.
450              Typically  the  action  of tcp_on_awol will be to close the ses‐
451              sion.
452
453              The variable TCP_INVALIDATE_ZLE will be a non-empty string if it
454              is  necessary  to  invalidate the line editor display using `zle
455              -I' before printing output from the function.
456
457              (`AWOL' is military jargon for `absent without  leave'  or  some
458              variation.   It  has  no pre-existing technical meaning known to
459              the author.)
460
461       tcp_on_close sess fd
462              This is called with the name of a session being closed  and  the
463              file  descriptor  which corresponded to that session.  Both will
464              be invalid by the time the function is called.
465
466       tcp_on_open sess fd
467              This is called after a new session has  been  defined  with  the
468              session  name and file descriptor as arguments.  If it returns a
469              non-zero status, opening the session is assumed to fail and  the
470              session  is  closed  again;  however,  tcp_open will continue to
471              attempt to open any remaining  sessions  given  on  the  command
472              line.
473
474       tcp_on_rename oldsess fd newsess
475              This  is  called after a session has been renamed with the three
476              arguments old session name, file descriptor, new session name.
477
478       tcp_on_spam sess command ...
479              This is called once for each session spammed, just before a com‐
480              mand  is  executed for a session by tcp_spam.  The arguments are
481              the session name followed by the command list  to  be  executed.
482              If  tcp_spam  was  called  with the option -t, the first command
483              will be tcp_send.
484
485              This function is called after $TCP_SESS is set  to  reflect  the
486              session  to be spammed, but before any use of it is made.  Hence
487              it is possible to alter the value of $TCP_SESS within this func‐
488              tion.   For  example,  the  session  arguments to tcp_spam could
489              include extra information to be stripped off  and  processed  in
490              tcp_on_spam.
491
492              If the function sets the parameter $REPLY to `done', the command
493              line is not executed; in addition, no prompt is printed for  the
494              -v option to tcp_spam.
495
496       tcp_on_unalias alias fd
497              This  is  called with the name of an alias and the corresponding
498              session's file descriptor after an alias has been deleted.
499

TCP UTILITY FUNCTIONS

501       The following functions are used by the TCP function  system  but  will
502       rarely if ever need to be called directly.
503
504       tcp_fd_handler
505              This  is  the  function installed by tcp_open for handling input
506              from within the line editor, if that is required.  It is in  the
507              format documented for the builtin `zle -F' in zshzle(1) .
508
509              While active, the function sets the parameter TCP_HANDLER_ACTIVE
510              to 1.  This allows shell code called internally (for example, by
511              setting  tcp_on_read)  to tell if is being called when the shell
512              is otherwise idle at the editor prompt.
513
514       tcp_output [ -q ] -P prompt -F fd -S sess
515              This function is used for both logging and  handling  output  to
516              standard  output,  from  within  tcp_read and (if $TCP_OUTPUT is
517              set) tcp_send.
518
519              The prompt to use is specified by -P; the default is  the  empty
520              string.  It can contain:
521              %c     Expands  to 1 if the session is the current session, oth‐
522                     erwise  0.   Used  with  ternary  expressions   such   as
523                     `%(c.-.+)'  to output `+' for the current session and `-'
524                     otherwise.
525
526              %f     Replaced by the session's file descriptor.
527
528              %s     Replaced by the session name.
529
530              %%     Replaced by a single `%'.
531
532              The option -q suppresses output to standard output, but  not  to
533              any log files which are configured.
534
535              The  -S  and -F options are used to pass in the session name and
536              file descriptor for possible replacement in the prompt.
537

TCP USER PARAMETERS

539       Parameters follow the usual  convention  that  uppercase  is  used  for
540       scalars  and  integers, while lowercase is used for normal and associa‐
541       tive array.  It is always safe for user code to read these  parameters.
542       Some  parameters  may  also be set; these are noted explicitly.  Others
543       are included in this group as they are set by the function  system  for
544       the  user's  benefit,  i.e. setting them is typically not useful but is
545       benign.
546
547       It is often also useful to make settable parameters local  to  a  func‐
548       tion.   For example, `local TCP_SILENT=1' specifies that data read dur‐
549       ing the function call will not be printed to standard  output,  regard‐
550       less   of   the   setting   outside  the  function.   Likewise,  `local
551       TCP_SESS=sess' sets a session for  the  duration  of  a  function,  and
552       `local  TCP_PROMPT='  specifies that no prompt is used for input during
553       the function.
554
555       tcp_expect_lines
556              Array.   The  set  of  lines  read  during  the  last  call   to
557              tcp_expect, including the last ($TCP_LINE).
558
559       tcp_filter
560              Array. May be set directly.  A set of extended globbing patterns
561              which, if matched in tcp_output, will cause the line not  to  be
562              printed  to  standard output.  The patterns should be defined as
563              described for the arguments to tcp_expect.  Output  of  line  to
564              log files is not affected.
565
566       TCP_HANDLER_ACTIVE
567              Scalar.  Set to 1 within tcp_fd_handler to indicate to functions
568              called recursively that they have been called during  an  editor
569              session.  Otherwise unset.
570
571       TCP_LINE
572              The last line read by tcp_read, and hence also tcp_expect.
573
574       TCP_LINE_FD
575              The   file   descriptor   from   which   $TCP_LINE   was   read.
576              ${tcp_by_fd[$TCP_LINE_FD]} will give the  corresponding  session
577              name.
578
579       tcp_lines
580              Array.  The  set of lines read during the last call to tcp_read,
581              including the last ($TCP_LINE).
582
583       TCP_LOG
584              May be set directly, although it is also controlled by  tcp_log.
585              The  name  of  a  file to which output from all sessions will be
586              sent.  The output is proceeded by the usual $TCP_PROMPT.  If  it
587              is  not an absolute path name, it will follow the user's current
588              directory.
589
590       TCP_LOG_SESS
591              May be set directly, although it is also controlled by  tcp_log.
592              The  prefix for a set of files to which output from each session
593              separately   will   be    sent;    the    full    filename    is
594              ${TCP_LOG_SESS}.sess.   Output to each file is raw; no prompt is
595              added.  If it is not an absolute path name, it will  follow  the
596              user's current directory.
597
598       tcp_no_spam_list
599              Array.  May be set directly.  See tcp_spam for how this is used.
600
601       TCP_OUTPUT
602              May  be set directly.  If a non-empty string, any data sent to a
603              session by tcp_send will be logged.  This  parameter  gives  the
604              prompt  to  be used in a file specified by $TCP_LOG but not in a
605              file generated from $TCP_LOG_SESS.  The prompt  string  has  the
606              same format as TCP_PROMPT and the same rules for its use apply.
607
608       TCP_PROMPT
609              May  be  set  directly.   Used  as  the  prefix for data read by
610              tcp_read which is printed to standard output or to the log  file
611              given  by $TCP_LOG, if any.  Any `%s', `%f' or `%%' occurring in
612              the string will be replaced by the name of the session, the ses‐
613              sion's  underlying  file  descriptor,  or  a single `%', respec‐
614              tively.  The expression `%c' expands to 1 if the  session  being
615              read  is  the  current  session,  else 0; this is most useful in
616              ternary expressions such as `%(c.-.+)' which outputs `+' if  the
617              session is the current one, else `-'.
618
619       TCP_READ_DEBUG
620              May be set directly.  If this has non-zero length, tcp_read will
621              give some limited diagnostics about data being read.
622
623       TCP_SECONDS_START
624              This value is created and initialised to zero by tcp_open.
625
626              The functions tcp_read and tcp_expect use  the  shell's  SECONDS
627              parameter  for  their own timing purposes.  If that parameter is
628              not of floating point type on entry to one of the functions,  it
629              will  create  a  local parameter SECONDS which is floating point
630              and set the parameter TCP_SECONDS_START to the previous value of
631              $SECONDS.   If  the  parameter  is already floating point, it is
632              used without a local copy being created and TCP_SECONDS_START is
633              not set.  As the global value is zero, the shell elapsed time is
634              guaranteed to be the sum of $SECONDS and $TCP_SECONDS_START.
635
636              This can be avoided by setting SECONDS globally  to  a  floating
637              point  value  using `typeset -F SECONDS'; then the TCP functions
638              will never make a local copy and never set TCP_SECONDS_START  to
639              a non-zero value.
640
641       TCP_SESS
642              May  be set directly.  The current session; must refer to one of
643              the sessions established by tcp_open.
644
645       TCP_SILENT
646              May be set directly, although it is also controlled by  tcp_log.
647              If of non-zero length, data read by tcp_read will not be written
648              to standard output, though may still be written to a log file.
649
650       tcp_spam_list
651              Array.  May be set directly.  See the description of  the  func‐
652              tion tcp_spam for how this is used.
653
654       TCP_TALK_ESCAPE
655              May  be  set  directly.   See  the  description  of the function
656              tcp_talk for how this is used.
657
658       TCP_TIMEOUT
659              May be set directly.  Currently this is only used by  the  func‐
660              tion tcp_command, see above.
661

TCP USER-DEFINED PARAMETERS

663       The following parameters are not set by the function system, but have a
664       special effect if set by the user.
665
666       tcp_on_read
667              This should be an associative array; if it is not, the behaviour
668              is undefined.  Each key is the name of a shell function or other
669              command, and the corresponding value is a shell  pattern  (using
670              EXTENDED_GLOB).   Every line read from a TCP session directly or
671              indirectly  using  tcp_read  (which  includes  lines   read   by
672              tcp_expect)  is  compared  against  the  pattern.   If  the line
673              matches, the command given in the key is called with  two  argu‐
674              ments: the name of the session from which the line was read, and
675              the line itself.
676
677              If any function called to handle a line returns a non-zero  sta‐
678              tus,  the  line  is not output.  Thus a tcp_on_read handler con‐
679              taining only the instruction `return 1' can be used to  suppress
680              output  of  particular  lines  (see, however, tcp_filter above).
681              However, the line is still stored  in  TCP_LINE  and  tcp_lines;
682              this occurs after all tcp_on_read processing.
683

TCP UTILITY PARAMETERS

685       These  parameters  are  controlled  by the function system; they may be
686       read directly, but should not usually be set by user code.
687
688       tcp_aliases
689              Associative array.  The keys are the names  of  sessions  estab‐
690              lished  with  tcp_open;  each value is a space-separated list of
691              aliases which refer to that session.
692
693       tcp_by_fd
694              Associative array.  The keys are session file descriptors;  each
695              value is the name of that session.
696
697       tcp_by_name
698              Associative  array.   The  keys  are the names of sessions; each
699              value is the file descriptor associated with that session.
700

TCP EXAMPLES

702       Here is a trivial example using a remote calculator.
703
704       TO create a calculator server on port 7337 (see the dc manual page  for
705       quite how infuriating the underlying command is):
706
707              tcp_proxy 7337 dc
708
709       To connect to this from the same host with a session also named `dc':
710
711              tcp_open localhost 7337 dc
712
713       To send a command to the remote session and wait a short while for out‐
714       put (assuming dc is the current session):
715
716              tcp_command 2 4 + p
717
718       To close the session:
719
720              tcp_close
721
722       The tcp_proxy needs to be killed to be stopped.   Note  this  will  not
723       usually kill any connections which have already been accepted, and also
724       that the port is not immediately available for reuse.
725
726       The following chunk of code puts a  list  of  sessions  into  an  xterm
727       header, with the current session followed by a star.
728
729              print -n "\033]2;TCP:" ${(k)tcp_by_name:/$TCP_SESS/$TCP_SESS\*} "\a"
730

TCP BUGS

732       The  function  tcp_read  uses the shell's normal read builtin.  As this
733       reads a complete line at once, data arriving without a terminating new‐
734       line can cause the function to block indefinitely.
735
736       Though  the  function suite works well for interactive use and for data
737       arriving in small amounts, the performance when large amounts  of  data
738       are being exchanged is likely to be extremely poor.
739
740
741
742zsh 4.3.10                       June 1, 2009                     ZSHTCPSYS(1)
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