zshtcpsys(1) - zsh tcp system



  • ZSHTCPSYS(1)                General Commands Manual               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  zshmodules(1)  .   This
           manual  page  describes  a  function suite based on the module.  If the
           module is installed, the functions are usually installed  at  the  same
           time,  in  which  case  they  will  be available for autoloading in the
           default function search path.  In addition to the  zsh/net/tcp  module,
           the  zsh/zselect  module  is  used to implement timeouts on read opera-
           tions.  For troubleshooting tips, consult the corresponding advice  for
           the zftp functions described in zshzftpsys(1) .
    
           There  are  functions  corresponding  to the basic I/O operations 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 sys-
           tem 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 ter-
           minal.   Other  facilities  available  including logging, filtering and
           configurable output prompts.
    
           To use the system where  it  is  available,  it  should  be  enough  to
           `autoload  -U tcp_open' and run tcp_open as documented below to start a
           session.  The tcp_open function will autoload the remaining functions.
    
    TCP USER FUNCTIONS
       Basic 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  are not
                  well-defined but  certainly  do  not  include  alphanumerics  or
                  underscores, and certainly do include whitespace.
    
                  In  the second case, one or more sessions to be opened are given
                  by name.  A  single  session  name  is  given  after  -s  and  a
                  comma-separated  list  after -l; both options may be repeated as
                  many times as necessary.  A failure 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 initiali-
                  sation  files,  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  white-
                  space.
    
                  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.  No function 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 connec-
                  tion is made to port on the local machine.   At  this  point,  a
                  session  is  created  in  the usual way and is largely indistin-
                  guishable 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 function system copes with this depends
                  on what actually underlies 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 typically the 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 must be read
                  explicitly.  Note, however, this is not necessary for  executing
                  complete  sets of send and read 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 if zle
                  is not active; `[[ -o zle]]' will test for this.
    
                  The  first  session to be opened becomes the current session and
                  subsequent calls to tcp_open do not change it.  The current ses-
                  sion  is  stored  in the parameter $TCP_SESS; see below for more
                  detail about the parameters 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 if none 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 ses-
                  sions 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 the option -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 on a list of
                  sessions  if  any  are given with -u, -l or -s, or all open ses-
                  sions if the option -a is given.   Any  of  the  -u,  -l  or  -s
                  options may be repeated or mixed together.  The -u option speci-
                  fies a file descriptor directly (only those managed by this sys-
                  tem are useful), the other two specify sessions as described for
                  tcp_open above.
    
                  The function checks for new data available on all  the  sessions
                  listed.   Unless the -b option is given, it will not block wait-
                  ing for new data.  Any one line of data from any of  the  avail-
                  able  sessions  will be read, stored in the parameter $TCP_LINE,
                  and displayed to 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 these parameters.  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 func-
                  tion 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 is  stored  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 increased accuracy.  With -t the
                  timeout is applied before each line read.  With -T, the  timeout
                  applies  to  the  overall operation, possibly including multiple
                  read operations if  the  option  -d  is  present;  without  this
                  option, there is no distinction between -t and -T.
    
                  The  function  does not print informational messages, but if the
                  option -q is given, no error message is printed for a  non-exis-
                  tent session.
    
                  A  return  status  of  2 indicates a timeout or no data to read.
                  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 differs little from a `print -r'
                  to the session's file descriptor, although it attempts  to  pre-
                  vent  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 sends them in
                  turn to the specified session(s) exactly as if they  were  given
                  as data arguments to individual tcp_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 they have 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 session will be echoed  to
                  the  log  file(s)  with  $TCP_OUTPUT in front where appropriate,
                  much in the manner of $TCP_PROMPT.
    
       Session Management
           tcp_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  subset  of
                  error messages.
    
           tcp_log [-asc] [ -n | -N ] [ logfile ]
                  With an argument logfile, all future input from tcp_read will be
                  logged to the named file.  Unless -a  (append)  is  given,  this
                  file  will  first  be truncated or created empty.  With no argu-
                  ments, 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 the filename,  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.
    
                  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  setting  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 associated
                  file descriptors.  The current session is marked  with  a  star.
                  For   use   in   functions,  direct  access  to  the  parameters
                  $tcp_by_name, $tcp_by_fd and $TCP_SESS is probably  more  conve-
                  nient; 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 ....  The first argument is
                  re-evaluated so as to expand aliases  etc.,  but  the  remaining
                  arguments  are  passed  through  as the 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  arguments  are
                  passed  to  tcp_send, then the function pauses waiting for data.
                  While data is arriving at least every $TCP_TIMEOUT (default 0.3)
                  seconds,  data  is handled and printed out according to the cur-
                  rent 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 con-
                  nection.  Within a programme or function it is generally  better
                  to handle reading data by a more explicit method.
    
           tcp_expect [ -q ] [ -p  var  | -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 this point status zero is
                  returned, the matching line is 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 the sessions specified
                  by -a, -s, or -l are used.
    
                  Each pattern is a standard zsh extended-globbing  pattern;  note
                  that  it  needs  to be quoted to avoid it being expanded immedi-
                  ately 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 matched  against  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  the
                  parameters  $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 timeout with -t or -T;  these  function
                  as  in  tcp_read,  specifying  a  per-read  or  overall timeout,
                  respectively, in seconds, as an integer or  floating-point  num-
                  ber.   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 the patterns
                  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 index -1 is used if there is a timeout and 0  if
                  there is no match.
    
                  The  option -P var works similarly to -p, but instead of numeri-
                  cal indexes the regular arguments must begin with a prefix  fol-
                  lowed by a colon: that prefix is then used as a tag to which var
                  is set when the argument matches.  The tag timeout  is  used  if
                  there  is  a  timeout and the empty string if there is no match.
                  Note it is acceptable for different arguments to start with  the
                  same prefix if the matches do not need to be distinguished.
    
                  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 is that 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 connection and
                  execute  a  command  with  I/O  redirected  to  the  connection.
                  Extreme  caution should be taken as there is no security whatso-
                  ever and this can leave your computer open to the  world.   Ide-
                  ally, it should only be used behind a firewall.
    
                  The first argument is a TCP port on which the function will lis-
                  ten.
    
                  The remaining arguments give a command and its arguments to exe-
                  cute  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 send the command line  as
                  data unless the -t (transmit) option is given.
    
                  The sessions may be selected explicitly with the standard -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 ses-
                  sions are chosen implicitly are  spammed  in  alphabetic  order;
                  sessions  given  by  the  $tcp_spam_list array or on the command
                  line are spammed in the order given.  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 modification 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  exe-
                  cuted  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 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 edi-
                  tor'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 alternative approach for sending data easily
                  to the current session.  One simple approach is  to  alias  some
                  special character (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  input  on 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 transfer a file
                  between two hosts within the shell.  Note,  however,  that  bulk
                  data  transfer is currently done using cat.  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
                  port  is 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 <input_file
    
                  As  these  two functions do not require tcp_open to set up a TCP
                  connection first, they may need to be autoloaded separately.
    
    TCP USER-DEFINED FUNCTIONS
           Certain functions, if defined by the user, will be called by the  func-
           tion  system  in certain contexts.  This facility depends on the module
           zsh/parameter, which is usually available 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  reus-
                  able, by default it removes it from the list of file descriptors
                  handled by this method and prints 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  nor-
                  mal  handling should still be performed; any other return status
                  indicates that  no  further  action  should  be  taken  and  the
                  tcp_fd_handler  should return immediately with the given status.
                  Typically the action of tcp_on_awol will be to  close  the  ses-
                  sion.
    
                  The variable TCP_INVALIDATE_ZLE will be a non-empty string if it
                  is necessary to invalidate the line editor  display  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 closed and the
                  file descriptor which corresponded to that session.   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;  however,  tcp_open  will  continue  to
                  attempt  to  open  any  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, just before a com-
                  mand is executed for a session by tcp_spam.  The  arguments  are
                  the  session  name  followed by the command 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 value of $TCP_SESS within this func-
                  tion.  For example, the  session  arguments  to  tcp_spam  could
                  include  extra  information  to be stripped off and processed in
                  tcp_on_spam.
    
                  If the function sets the parameter $REPLY to `done', the command
                  line  is not executed; in addition, no prompt 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 parameter TCP_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 handling output to
                  standard output, from within tcp_read  and  (if  $TCP_OUTPUT  is
                  set) tcp_send.
    
                  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 session,  oth-
                         erwise   0.    Used  with  ternary  expressions  such  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  associa-
           tive  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 to a func-
           tion.  For example, `local TCP_SILENT=1' specifies that data read  dur-
           ing  the  function call will not be printed to standard output, regard-
           less  of  the  setting  outside   the   function.    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 function.
    
           tcp_expect_lines
                  Array.    The  set  of  lines  read  during  the  last  call  to
                  tcp_expect, including the last ($TCP_LINE).
    
           tcp_filter
                  Array. May be set directly.  A set of extended globbing patterns
                  which,  if  matched in tcp_output, will cause the line not to be
                  printed to standard output.  The patterns should be  defined  as
                  described  for  the  arguments to tcp_expect.  Output of line to
                  log files is not affected.
    
           TCP_HANDLER_ACTIVE
                  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  to  tcp_read,
                  including the last ($TCP_LINE).
    
           TCP_LOG
                  May  be set directly, although it is also controlled by tcp_log.
                  The name of a file to which output from  all  sessions  will  be
                  sent.   The output is proceeded by the usual $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 by tcp_log.
                  The prefix for a set of files to which output from each  session
                  separately    will    be    sent;    the    full   filename   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 specified 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  read  by
                  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 ses-
                  sion's underlying file descriptor,  or  a  single  `%',  respec-
                  tively.   The  expression `%c' expands to 1 if the session being
                  read is the current session, else 0;  this  is  most  useful  in
                  ternary  expressions such as `%(c.-.+)' which outputs `+' if the
                  session is the current one, else `-'.
    
                  If the prompt starts with %P, this is stripped and the  complete
                  result  of  the previous stage is passed through standard prompt
                  %-style formatting before being output.
    
           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 by tcp_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 entry to one of the functions, it
                  will create a local parameter SECONDS which  is  floating  point
                  and set the parameter 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 and TCP_SECONDS_START is
                  not set.  As the global value is zero, the shell elapsed time is
                  guaranteed to be the sum of $SECONDS and $TCP_SECONDS_START.
    
                  This  can  be  avoided by setting SECONDS globally to a floating
                  point value using `typeset -F SECONDS'; then the  TCP  functions
                  will  never make a local copy and never set TCP_SECONDS_START to
                  a non-zero value.
    
           TCP_SESS
                  May be set directly.  The current session; must refer to one  of
                  the sessions established by tcp_open.
    
           TCP_SILENT
                  May  be set directly, although it is also controlled by tcp_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 of the func-
                  tion tcp_spam for how this is used.
    
           TCP_TALK_ESCAPE
                  May be set  directly.   See  the  description  of  the  function
                  tcp_talk for how this is used.
    
           TCP_TIMEOUT
                  May  be  set directly.  Currently this is only used by the func-
                  tion tcp_command, see above.
    
    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 corresponding value is a shell pattern (using
                  EXTENDED_GLOB).  Every line read from a TCP session directly  or
                  indirectly   using   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 argu-
                  ments: the name of the session from which the line was read, and
                  the line itself.
    
                  If  any function called to handle a line returns a non-zero sta-
                  tus, the line is not output.  Thus a  tcp_on_read  handler  con-
                  taining  only the instruction `return 1' can be used to suppress
                  output of particular lines  (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 sessions estab-
                  lished 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 descriptors; 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):
    
                  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 out-
           put (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 without a terminating new-
           line can cause the function to block indefinitely.
    
           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 attributes:
    
    
           +---------------+------------------+
           |ATTRIBUTE TYPE | ATTRIBUTE VALUE  |
           +---------------+------------------+
           |Availability   | shell/zsh        |
           +---------------+------------------+
           |Stability      | Volatile         |
           +---------------+------------------+
    NOTES
           This    software    was    built    from    source     available     at
           https://java.net/projects/solaris-userland.    The  original  community
           source     was      downloaded      from       http://downloads.source-
           forge.net/project/zsh/zsh/5.0.7/zsh-5.0.7.tar.bz2
    
           Further information about this software can be found on the open source
           community website at http://www.zsh.org/.
    
    
    
    zsh 5.0.7                       October 7, 2014                   ZSHTCPSYS(1)
    

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