(zsh.info.gz) TCP Functions

Info Catalog (zsh.info.gz) TCP Function System (zsh.info.gz) TCP Parameters
 
 24.2 TCP User Functions
 =======================
 
 24.2.1 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 initialisation 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 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.  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 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 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 session
      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 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 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 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 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 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 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 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 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-existent
      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 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 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.
 
 24.2.2 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 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 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 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 ....  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.
 
 24.2.3 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 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 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 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
      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 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 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 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 whatsoever and this
      can leave your computer open to the world.  Ideally, it should only
      be 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 arguments 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 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 sessions.
 
      Normally, any sessions added by the '-a' flag or when all sessions
      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 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 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 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.
 
 24.2.4 '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.
 
 24.3 TCP User-defined Functions
 ===============================
 
 Certain functions, if defined by the user, will be called by the
 function 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 reusable,
      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 normal 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 session.
 
      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
      command 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 function.
      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.
 
 24.4 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  Zle Builtins .
 
      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, otherwise
           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.
 
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