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EXPECT(1)							     EXPECT(1)

NAME
       expect - programmed dialogue with interactive programs, Version 5

SYNOPSIS
       expect [ -dDinN ] [ -c cmds ] [ -[f|b] ] cmdfile ] [ args ]

INTRODUCTION
       Expect  is a program that "talks" to other interactive programs accord‐
       ing to a script.	 Following  the	 script,  Expect  knows	 what  can  be
       expected	 from  a  program and what the correct response should be.  An
       interpreted language provides branching and high-level  control	struc‐
       tures  to  direct the dialogue.	In addition, the user can take control
       and interact directly when desired, afterward returning control to  the
       script.

       Expectk is a mixture of Expect and Tk.  It behaves just like Expect and
       Tk's wish.  Expect can also be used directly in	C  or  C++  (that  is,
       without Tcl).  See libexpect(3).

       The name "Expect" comes from the idea of send/expect sequences popular‐
       ized by uucp, kermit and other modem control programs.  However	unlike
       uucp,  Expect is generalized so that it can be run as a user-level com‐
       mand with any program and task in mind.	Expect can  actually  talk  to
       several programs at the same time.

       For example, here are some things Expect can do:

	      ·	  Cause	 your computer to dial you back, so that you can login
		  without paying for the call.

	      ·	  Start a game (e.g., rogue) and if the optimal	 configuration
		  doesn't  appear, restart it (again and again) until it does,
		  then hand over control to you.

	      ·	  Run fsck, and in response to its  questions,	answer	"yes",
		  "no"	or  give  control  back to you, based on predetermined
		  criteria.

	      ·	  Connect to another network or	 BBS  (e.g.,  MCI  Mail,  Com‐
		  puServe)  and	 automatically	retrieve  your mail so that it
		  appears as if it was originally sent to your local system.

	      ·	  Carry environment variables, current directory, or any  kind
		  of information across rlogin, telnet, tip, su, chgrp, etc.

       There  are  a  variety  of  reasons  why the shell cannot perform these
       tasks.  (Try, you'll see.)  All are possible with Expect.

       In general, Expect is useful for running	 any  program  which  requires
       interaction between the program and the user.  All that is necessary is
       that the interaction can be characterized programmatically.  Expect can
       also give the user back control (without halting the program being con‐
       trolled) if desired.  Similarly, the user can  return  control  to  the
       script at any time.

USAGE
       Expect  reads  cmdfile  for  a list of commands to execute.  Expect may
       also be invoked implicitly on systems which support the #! notation  by
       marking	the  script  executable,  and  making  the  first line in your
       script:

	   #!/usr/local/bin/expect -f

       Of course, the  path  must  accurately  describe	 where	Expect	lives.
       /usr/local/bin is just an example.

       The -c flag prefaces a command to be executed before any in the script.
       The command should be quoted to prevent being broken up by  the	shell.
       This  option may be used multiple times.	 Multiple commands may be exe‐
       cuted with a single -c by separating them  with	semicolons.   Commands
       are  executed  in  the  order  they  appear.  (When using Expectk, this
       option is specified as -command.)

       The -d flag enables some diagnostic  output,  which  primarily  reports
       internal	 activity  of commands such as expect and interact.  This flag
       has the same effect as "exp_internal 1" at the beginning of  an	Expect
       script,	plus the version of Expect is printed.	(The strace command is
       useful for tracing statements, and the  trace  command  is  useful  for
       tracing	variable  assignments.)	  (When	 using Expectk, this option is
       specified as -diag.)

       The -D flag enables an interactive debugger.  An integer	 value	should
       follow.	 The  debugger will take control before the next Tcl procedure
       if the value is non-zero or if a ^C is pressed (or a breakpoint is hit,
       or  other appropriate debugger command appears in the script).  See the
       README file or SEE ALSO (below) for more information on	the  debugger.
       (When using Expectk, this option is specified as -Debug.)

       The -f flag prefaces a file from which to read commands from.  The flag
       itself is optional as it is only useful when using the #! notation (see
       above),	so  that  other arguments may be supplied on the command line.
       (When using Expectk, this option is specified as -file.)

       By default, the command file is read into memory and  executed  in  its
       entirety.   It  is  occasionally	 desirable to read files one line at a
       time.  For example, stdin is read this way.  In order  to  force	 arbi‐
       trary  files  to	 be  handled  this  way, use the -b flag.  (When using
       Expectk, this option is specified as -buffer.)

       If the string "-" is supplied as a filename,  standard  input  is  read
       instead.	 (Use "./-" to read from a file actually named "-".)

       The  -i flag causes Expect to interactively prompt for commands instead
       of reading them from a file.  Prompting is terminated via the exit com‐
       mand or upon EOF.  See interpreter (below) for more information.	 -i is
       assumed if neither a command file nor -c is used.  (When using Expectk,
       this option is specified as -interactive.)

       --  may	be  used to delimit the end of the options.  This is useful if
       you want to pass an option-like argument	 to  your  script  without  it
       being  interpreted  by  Expect.	 This can usefully be placed in the #!
       line to prevent any flag-like interpretation by Expect.	 For  example,
       the  following  will leave the original arguments (including the script
       name) in the variable argv.

	   #!/usr/local/bin/expect --

       Note that  the  usual  getopt(3)	 and  execve(2)	 conventions  must  be
       observed when adding arguments to the #! line.

       The  file  $exp_library/expect.rc  is sourced automatically if present,
       unless the -N flag is used.  (When using Expectk, this option is speci‐
       fied  as	 -NORC.)   Immediately	after  this,  the file ~/.expect.rc is
       sourced automatically, unless the -n flag is used.  If the  environment
       variable DOTDIR is defined, it is treated as a directory and .expect.rc
       is read from there.  (When using Expectk, this option is	 specified  as
       -norc.)	This sourcing occurs only after executing any -c flags.

       -v  causes  Expect  to  print its version number and exit.  (The corre‐
       sponding flag in Expectk, which uses long flag names, is -version.)

       Optional args are constructed into a list and stored  in	 the  variable
       named argv.  argc is initialized to the length of argv.

       argv0  is  defined to be the name of the script (or binary if no script
       is used).  For example, the following prints out the name of the script
       and the first three arguments:

	   send_user "$argv0 [lrange $argv 0 2]\n"

COMMANDS
       Expect  uses  Tcl  (Tool	 Command Language).  Tcl provides control flow
       (e.g., if, for, break), expression evaluation and  several  other  fea‐
       tures such as recursion, procedure definition, etc.  Commands used here
       but not defined (e.g., set, if, exec) are Tcl  commands	(see  tcl(3)).
       Expect supports additional commands, described below.  Unless otherwise
       specified, commands return the empty string.

       Commands are listed alphabetically so that they can be quickly located.
       However,	 new users may find it easier to start by reading the descrip‐
       tions of spawn, send, expect, and interact, in that order.

       Note that the best introduction to the language (both Expect  and  Tcl)
       is provided in the book "Exploring Expect" (see SEE ALSO below).	 Exam‐
       ples are included in this man page but they are very limited since this
       man page is meant primarily as reference material.

       Note  that in the text of this man page, "Expect" with an uppercase "E"
       refers to the Expect program  while  "expect"  with  a  lower-case  "e"
       refers to the expect command within the Expect program.)

       close [-slave] [-onexec 0|1] [-i spawn_id]
	     closes  the  connection to the current process.  Most interactive
	     programs will detect EOF on their stdin and exit; thus close usu‐
	     ally  suffices to kill the process as well.  The -i flag declares
	     the process to close corresponding to the named spawn_id.

	     Both expect and interact will detect  when	 the  current  process
	     exits and implicitly do a close.  But if you kill the process by,
	     say, "exec kill $pid", you will need to explicitly call close.

	     The -onexec flag determines whether the spawn id will  be	closed
	     in	 any new spawned processes or if the process is overlayed.  To
	     leave a spawn id open, use the value 0.  A non-zero integer value
	     will force the spawn closed (the default) in any new processes.

	     The  -slave  flag	closes the slave associated with the spawn id.
	     (See "spawn -pty".)  When the connection is closed, the slave  is
	     automatically closed as well if still open.

	     No	 matter whether the connection is closed implicitly or explic‐
	     itly, you should call wait to clear up the	 corresponding	kernel
	     process slot.  close does not call wait since there is no guaran‐
	     tee that closing a process connection will cause it to exit.  See
	     wait below for more info.

       debug [[-now] 0|1]
	     controls  a Tcl debugger allowing you to step through statements,
	     set breakpoints, etc.

	     With no arguments, a 1 is returned if the debugger	 is  not  run‐
	     ning, otherwise a 0 is returned.

	     With  a  1 argument, the debugger is started.  With a 0 argument,
	     the debugger is stopped.  If a 1 argument is preceded by the -now
	     flag, the debugger is started immediately (i.e., in the middle of
	     the debug command itself).	 Otherwise, the	 debugger  is  started
	     with the next Tcl statement.

	     The  debug	 command  does	not change any traps.  Compare this to
	     starting Expect with the -D flag (see above).

	     See the README file or SEE ALSO (below) for more  information  on
	     the debugger.

       disconnect
	     disconnects  a  forked  process  from the terminal.  It continues
	     running in the background.	 The process is given its own  process
	     group (if possible).  Standard I/O is redirected to /dev/null.

	     The  following  fragment  uses disconnect to continue running the
	     script in the background.

		 if [fork]!=0 exit
		 disconnect
		 . . .

	     The following script reads a password, and then  runs  a  program
	     every  hour  that	demands	 a  password each time it is run.  The
	     script supplies the password so that you only  have  to  type  it
	     once.   (See  the stty command which demonstrates how to turn off
	     password echoing.)

		 send_user "password?\ "
		 expect_user -re "(.*)\n"
		 for {} 1 {} {
		     if [fork]!=0 {sleep 3600;continue}
		     disconnect
		     spawn priv_prog
		     expect Password:
		     send "$expect_out(1,string)\r"
		     . . .
		     exit
		 }

	     An advantage to using  disconnect	over  the  shell  asynchronous
	     process  feature (&) is that Expect can save the terminal parame‐
	     ters prior to disconnection, and then later  apply	 them  to  new
	     ptys.   With  &, Expect does not have a chance to read the termi‐
	     nal's parameters since the terminal is  already  disconnected  by
	     the time Expect receives control.

       exit [-opts] [status]
	     causes Expect to exit or otherwise prepare to do so.

	     The  -onexit  flag causes the next argument to be used as an exit
	     handler.  Without	an  argument,  the  current  exit  handler  is
	     returned.

	     The  -noexit flag causes Expect to prepare to exit but stop short
	     of actually returning control to the operating system.  The user-
	     defined exit handler is run as well as Expect's own internal han‐
	     dlers.  No further Expect commands should be executed.   This  is
	     useful  if you are running Expect with other Tcl extensions.  The
	     current interpreter (and main window if in	 the  Tk  environment)
	     remain  so	 that  other Tcl extensions can clean up.  If Expect's
	     exit is called again (however this might occur), the handlers are
	     not rerun.

	     Upon  exiting,  all  connections to spawned processes are closed.
	     Closure will be detected as an EOF by  spawned  processes.	  exit
	     takes  no other actions beyond what the normal _exit(2) procedure
	     does.  Thus, spawned processes that do not check for EOF may con‐
	     tinue  to	run.  (A variety of conditions are important to deter‐
	     mining, for example, what signals a spawned process will be sent,
	     but   these  are  system-dependent,  typically  documented	 under
	     exit(3).)	Spawned processes that continue to run will be	inher‐
	     ited by init.

	     status  (or 0 if not specified) is returned as the exit status of
	     Expect.  exit is implicitly executed if the end of the script  is
	     reached.

       exp_continue
	     The command exp_continue allows expect itself to continue execut‐
	     ing rather than returning as it normally would.  (See expect  for
	     more information.)

       exp_internal [-f file] value
	     causes  further  commands to send diagnostic information internal
	     to Expect to stderr if value is non-zero.	This  output  is  dis‐
	     abled  if	value is 0.  The diagnostic information includes every
	     character received, and every attempt made to match  the  current
	     output against the patterns.

	     If the optional file is supplied, all normal and debugging output
	     is written to that file (regardless of the value of value).   Any
	     previous diagnostic output file is closed.

	     The -info flag causes exp_internal to return a description of the
	     most recent non-info arguments given.

       exp_open [args] [-i spawn_id]
	     returns a Tcl file identifier that corresponds  to	 the  original
	     spawn  id.	  The  file  identifier can then be used as if it were
	     opened by Tcl's open command.  (The spawn id should no longer  be
	     used.  A wait should not be executed.

	     The  -leaveopen  flag leaves the spawn id open for access through
	     Expect commands.  A wait must be executed on the spawn id.

       exp_pid [-i spawn_id]
	     returns the process id corresponding  to  the  currently  spawned
	     process.  If the -i flag is used, the pid returned corresponds to
	     that of the given spawn id.

       exp_send
	     is an alias for send.

       exp_send_error
	     is an alias for send_error.

       exp_send_log
	     is an alias for send_log.

       exp_send_tty
	     is an alias for send_tty.

       exp_send_user
	     is an alias for send_user.

       exp_version [[-exit] version]
	     is useful for assuring that the script  is	 compatible  with  the
	     current version of Expect.

	     With  no  arguments,  the	current version of Expect is returned.
	     This version may then be encoded in your script.  If you actually
	     know  that you are not using features of recent versions, you can
	     specify an earlier version.

	     Versions consist of three numbers separated by  dots.   First  is
	     the  major number.	 Scripts written for versions of Expect with a
	     different major number will almost certainly not work.   exp_ver‐
	     sion returns an error if the major numbers do not match.

	     Second is the minor number.  Scripts written for a version with a
	     greater minor number than the current  version  may  depend  upon
	     some new feature and might not run.  exp_version returns an error
	     if the major numbers  match,  but	the  script  minor  number  is
	     greater than that of the running Expect.

	     Third  is	a number that plays no part in the version comparison.
	     However, it is incremented when the Expect software  distribution
	     is	 changed  in  any  way, such as by additional documentation or
	     optimization.  It is reset to 0 upon each new minor version.

	     With the -exit flag, Expect prints an error and exits if the ver‐
	     sion is out of date.

       expect [[-opts] pat1 body1] ... [-opts] patn [bodyn]
	     waits  until  one of the patterns matches the output of a spawned
	     process, a specified time period has passed, or an end-of-file is
	     seen.  If the final body is empty, it may be omitted.

	     Patterns  from  the most recent expect_before command are implic‐
	     itly used before any other	 patterns.   Patterns  from  the  most
	     recent  expect_after  command are implicitly used after any other
	     patterns.

	     If the arguments to the entire expect statement require more than
	     one  line,	 all  the  arguments may be "braced" into one so as to
	     avoid terminating each line with a backslash.  In this one	 case,
	     the usual Tcl substitutions will occur despite the braces.

	     If	 a  pattern is the keyword eof, the corresponding body is exe‐
	     cuted upon end-of-file.  If a pattern is the keyword timeout, the
	     corresponding  body is executed upon timeout.  If no timeout key‐
	     word is used, an implicit null action is executed	upon  timeout.
	     The  default  timeout  period  is	10 seconds but may be set, for
	     example to 30, by the command  "set  timeout  30".	  An  infinite
	     timeout  may  be designated by the value -1.  If a pattern is the
	     keyword default, the corresponding body is executed  upon	either
	     timeout or end-of-file.

	     If	 a  pattern  matches, then the corresponding body is executed.
	     expect returns the result of the body (or the empty string if  no
	     pattern matched).	In the event that multiple patterns match, the
	     one appearing first is used to select a body.

	     Each time new output arrives, it is compared to each  pattern  in
	     the  order	 they are listed.  Thus, you may test for absence of a
	     match by making the last pattern something guaranteed to  appear,
	     such  as  a  prompt.  In situations where there is no prompt, you
	     must use timeout (just like you would  if	you  were  interacting
	     manually).

	     Patterns  are  specified in three ways.  By default, patterns are
	     specified as with Tcl's string match command.  (Such patterns are
	     also  similar  to C-shell regular expressions usually referred to
	     as "glob" patterns).  The -gl flag may may	 be  used  to  protect
	     patterns  that  might otherwise match expect flags from doing so.
	     Any pattern beginning with a "-" should be	 protected  this  way.
	     (All strings starting with "-" are reserved for future options.)

	     For example, the following fragment looks for a successful login.
	     (Note that abort is presumed to be a procedure defined  elsewhere
	     in the script.)

		 expect {
		     busy		{puts busy\n ; exp_continue}
		     failed		abort
		     "invalid password" abort
		     timeout		abort
		     connected
		 }

	     Quotes  are  necessary  on the fourth pattern since it contains a
	     space, which  would  otherwise  separate  the  pattern  from  the
	     action.   Patterns with the same action (such as the 3rd and 4th)
	     require listing the actions again.	 This can be  avoid  by	 using
	     regexp-style  patterns  (see below).  More information on forming
	     glob-style patterns can be found in the Tcl manual.

	     Regexp-style patterns follow the syntax defined by	 Tcl's	regexp
	     (short  for  "regular  expression") command.  regexp patterns are
	     introduced with the  flag	-re.   The  previous  example  can  be
	     rewritten using a regexp as:

		 expect {
		     busy	{puts busy\n ; exp_continue}
		     -re "failed|invalid password" abort
		     timeout	abort
		     connected
		 }

	     Both  types  of  patterns are "unanchored".  This means that pat‐
	     terns do not have to match the entire string, but can  begin  and
	     end  the match anywhere in the string (as long as everything else
	     matches).	Use ^ to match the beginning of a  string,  and	 $  to
	     match  the	 end.	Note  that if you do not wait for the end of a
	     string, your responses can easily end up in  the  middle  of  the
	     string  as they are echoed from the spawned process.  While still
	     producing correct results, the output can look unnatural.	 Thus,
	     use of $ is encouraged if you can exactly describe the characters
	     at the end of a string.

	     Note that in many editors, the ^ and $ match  the	beginning  and
	     end  of  lines  respectively. However, because expect is not line
	     oriented, these characters match the beginning  and  end  of  the
	     data  (as opposed to lines) currently in the expect matching buf‐
	     fer.  (Also, see the note below on "system indigestion.")

	     The -ex flag causes the pattern  to  be  matched  as  an  "exact"
	     string.   No  interpretation  of  *, ^, etc is made (although the
	     usual Tcl conventions must still be  observed).   Exact  patterns
	     are always unanchored.

	     The  -nocase  flag	 causes	 uppercase characters of the output to
	     compare as if they were lowercase characters.  The pattern is not
	     affected.

	     While  reading  output,  more  than  2000 bytes can force earlier
	     bytes to be "forgotten".  This may be changed with	 the  function
	     match_max.	 (Note that excessively large values can slow down the
	     pattern matcher.)	If patlist is full_buffer,  the	 corresponding
	     body  is  executed	 if  match_max bytes have been received and no
	     other patterns have matched.  Whether or not the full_buffer key‐
	     word   is	 used,	 the   forgotten  characters  are  written  to
	     expect_out(buffer).

	     If patlist is the keyword null, and nulls are  allowed  (via  the
	     remove_nulls  command),  the  corresponding body is executed if a
	     single ASCII 0 is matched.	 It is not possible to match  0	 bytes
	     via glob or regexp patterns.

	     Upon matching a pattern (or eof or full_buffer), any matching and
	     previously	 unmatched   output   is   saved   in	the   variable
	     expect_out(buffer).   Up  to 9 regexp substring matches are saved
	     in	     the      variables	     expect_out(1,string)      through
	     expect_out(9,string).  If the -indices flag is used before a pat‐
	     tern, the starting and ending indices (in	a  form	 suitable  for
	     lrange)   of   the	  10  strings  are  stored  in	the  variables
	     expect_out(X,start) and expect_out(X,end) where  X	 is  a	digit,
	     corresponds to the substring position in the buffer.  0 refers to
	     strings which matched the entire pattern  and  is	generated  for
	     glob  patterns  as	 well  as  regexp patterns.  For example, if a
	     process has produced output of "abcdefgh\n", the result of:

		 expect "cd"

	     is as if the following statements had executed:

		 set expect_out(0,string) cd
		 set expect_out(buffer) abcd

	     and "efgh\n" is left in the output buffer.	 If a process produced
	     the output "abbbcabkkkka\n", the result of:

		 expect -indices -re "b(b*).*(k+)"

	     is as if the following statements had executed:

		 set expect_out(0,start) 1
		 set expect_out(0,end) 10
		 set expect_out(0,string) bbbcabkkkk
		 set expect_out(1,start) 2
		 set expect_out(1,end) 3
		 set expect_out(1,string) bb
		 set expect_out(2,start) 10
		 set expect_out(2,end) 10
		 set expect_out(2,string) k
		 set expect_out(buffer) abbbcabkkkk

	     and "a\n" is left in the output buffer.  The pattern "*" (and -re
	     ".*") will flush the output buffer without reading any more  out‐
	     put from the process.

	     Normally,	the matched output is discarded from Expect's internal
	     buffers.  This may be prevented by prefixing a pattern  with  the
	     -notransfer  flag.	 This flag is especially useful in experiment‐
	     ing (and can be abbreviated to "-n" for convenience while experi‐
	     menting).

	     The  spawn	 id  associated	 with  the  matching output (or eof or
	     full_buffer) is stored in expect_out(spawn_id).

	     The -timeout flag causes the current expect command  to  use  the
	     following	value  as  a timeout instead of using the value of the
	     timeout variable.

	     By default, patterns are matched against output from the  current
	     process,  however	the -i flag declares the output from the named
	     spawn_id list be matched against any following  patterns  (up  to
	     the  next	-i).   The spawn_id list should either be a whitespace
	     separated list of spawn_ids or a variable	referring  to  such  a
	     list of spawn_ids.

	     For example, the following example waits for "connected" from the
	     current process, or "busy", "failed" or "invalid  password"  from
	     the spawn_id named by $proc2.

		 expect {
		     -i $proc2 busy {puts busy\n ; exp_continue}
		     -re "failed|invalid password" abort
		     timeout abort
		     connected
		 }

	     The  value	 of  the  global  variable any_spawn_id may be used to
	     match patterns to any spawn_ids that are named with all other  -i
	     flags in the current expect command.  The spawn_id from a -i flag
	     with no associated pattern (i.e., followed immediately by another
	     -i)  is  made  available to any other patterns in the same expect
	     command associated with any_spawn_id.

	     The -i flag may also name a global variable  in  which  case  the
	     variable is read for a list of spawn ids.	The variable is reread
	     whenever it changes.  This provides a way	of  changing  the  I/O
	     source  while  the	 command  is in execution.  Spawn ids provided
	     this way are called "indirect" spawn ids.

	     Actions such as  break  and  continue  cause  control  structures
	     (i.e.,  for,  proc)  to  behave  in  the  usual way.  The command
	     exp_continue allows expect itself to  continue  executing	rather
	     than returning as it normally would.

	     This  is  useful  for  avoiding explicit loops or repeated expect
	     statements.  The following example is part of a fragment to auto‐
	     mate  rlogin.   The  exp_continue avoids having to write a second
	     expect statement (to look for the prompt  again)  if  the	rlogin
	     prompts for a password.

		 expect {
		     Password: {
			 stty -echo
			 send_user "password (for $user) on $host: "
			 expect_user -re "(.*)\n"
			 send_user "\n"
			 send "$expect_out(1,string)\r"
			 stty echo
			 exp_continue
		     } incorrect {
			 send_user "invalid password or account\n"
			 exit
		     } timeout {
			 send_user "connection to $host timed out\n"
			 exit
		     } eof {
			 send_user \
			     "connection to host failed: $expect_out(buffer)"
			 exit
		     } -re $prompt
		 }

	     For  example,  the	 following fragment might help a user guide an
	     interaction that is already totally automated.  In this case, the
	     terminal  is put into raw mode.  If the user presses "+", a vari‐
	     able is incremented.  If "p" is pressed, several returns are sent
	     to	 the process, perhaps to poke it in some way, and "i" lets the
	     user interact with the process, effectively stealing away control
	     from  the script.	In each case, the exp_continue allows the cur‐
	     rent expect to continue pattern matching after executing the cur‐
	     rent action.

		 stty raw -echo
		 expect_after {
		     -i $user_spawn_id
		     "p" {send "\r\r\r"; exp_continue}
		     "+" {incr foo; exp_continue}
		     "i" {interact; exp_continue}
		     "quit" exit
		 }

	     By	 default, exp_continue resets the timeout timer.  The timer is
	     not restarted, if exp_continue is called with the -continue_timer
	     flag.

       expect_after [expect_args]
	     works  identically	 to  the expect_before except that if patterns
	     from both expect and expect_after can match, the  expect  pattern
	     is used.  See the expect_before command for more information.

       expect_background [expect_args]
	     takes  the	 same  arguments as expect, however it returns immedi‐
	     ately.  Patterns are tested whenever new input arrives.  The pat‐
	     tern timeout and default are meaningless to expect_background and
	     are silently discarded.  Otherwise, the expect_background command
	     uses  expect_before  and  expect_after  patterns just like expect
	     does.

	     When expect_background actions are	 being	evaluated,  background
	     processing for the same spawn id is blocked.  Background process‐
	     ing is unblocked when the	action	completes.   While  background
	     processing is blocked, it is possible to do a (foreground) expect
	     on the same spawn id.

	     It is not possible to execute an  expect  while  an  expect_back‐
	     ground is unblocked.  expect_background for a particular spawn id
	     is deleted by declaring a new  expect_background  with  the  same
	     spawn  id.	  Declaring  expect_background with no pattern removes
	     the given spawn id from the ability  to  match  patterns  in  the
	     background.

       expect_before [expect_args]
	     takes  the	 same  arguments as expect, however it returns immedi‐
	     ately.  Pattern-action pairs from the most	 recent	 expect_before
	     with  the	same  spawn  id	 are implicitly added to any following
	     expect commands.  If a pattern matches, it is treated  as	if  it
	     had  been specified in the expect command itself, and the associ‐
	     ated body is executed in the context of the expect	 command.   If
	     patterns  from  both  expect_before  and  expect  can  match, the
	     expect_before pattern is used.

	     If no pattern is specified, the spawn id is not checked  for  any
	     patterns.

	     Unless  overridden	 by  a	-i  flag, expect_before patterns match
	     against the spawn id defined at the time that  the	 expect_before
	     command was executed (not when its pattern is matched).

	     The  -info flag causes expect_before to return the current speci‐
	     fications of what patterns it will match.	By default, it reports
	     on	 the current spawn id.	An optional spawn id specification may
	     be given for information on that spawn id.	 For example

		 expect_before -info -i $proc

	     At most one spawn id specification may be given.  The flag -indi‐
	     rect  suppresses  direct  spawn  ids that come only from indirect
	     specifications.

	     Instead of a spawn id specification, the flag "-all"  will	 cause
	     "-info" to report on all spawn ids.

	     The  output  of  the  -info flag can be reused as the argument to
	     expect_before.

       expect_tty [expect_args]
	     is like expect but it reads characters from /dev/tty  (i.e.  key‐
	     strokes  from  the	 user).	  By  default, reading is performed in
	     cooked mode.  Thus, lines must end with a	return	in  order  for
	     expect  to	 see them.  This may be changed via stty (see the stty
	     command below).

       expect_user [expect_args]
	     is like expect but it reads  characters  from  stdin  (i.e.  key‐
	     strokes  from  the	 user).	  By  default, reading is performed in
	     cooked mode.  Thus, lines must end with a	return	in  order  for
	     expect  to	 see them.  This may be changed via stty (see the stty
	     command below).

       fork  creates a new process.  The new process is an exact copy  of  the
	     current  Expect  process.	 On success, fork returns 0 to the new
	     (child) process and returns the process ID of the	child  process
	     to	 the  parent  process.	 On failure (invariably due to lack of
	     resources, e.g., swap space, memory), fork returns -1 to the par‐
	     ent process, and no child process is created.

	     Forked  processes exit via the exit command, just like the origi‐
	     nal process.  Forked processes are allowed to write  to  the  log
	     files.  If you do not disable debugging or logging in most of the
	     processes, the result can be confusing.

	     Some pty implementations may be confused by multiple readers  and
	     writers,  even  momentarily.   Thus,  it is safest to fork before
	     spawning processes.

       interact [string1 body1] ... [stringn [bodyn]]
	     gives control of the current process to the user,	so  that  key‐
	     strokes  are  sent	 to  the  current  process, and the stdout and
	     stderr of the current process are returned.

	     String-body pairs may be specified as arguments,  in  which  case
	     the  body	is  executed when the corresponding string is entered.
	     (By default, the string is not  sent  to  the  current  process.)
	     The interpreter command is assumed, if the final body is missing.

	     If	 the  arguments	 to the entire interact statement require more
	     than one line, all the arguments may be "braced" into one	so  as
	     to	 avoid	terminating  each  line with a backslash.  In this one
	     case, the usual Tcl substitutions will occur despite the braces.

	     For example, the following command runs interact with the follow‐
	     ing  string-body  pairs  defined:	 When ^Z is pressed, Expect is
	     suspended.	 (The -reset flag restores the terminal modes.)	  When
	     ^A	 is  pressed,  the  user  sees "you typed a control-A" and the
	     process is sent a ^A.  When $ is pressed, the user sees the date.
	     When  ^C is pressed, Expect exits.	 If "foo" is entered, the user
	     sees "bar".  When ~~ is  pressed,	the  Expect  interpreter  runs
	     interactively.

		 set CTRLZ \032
		 interact {
		     -reset $CTRLZ {exec kill -STOP [pid]}
		     \001   {send_user "you typed a control-A\n";
			     send "\001"
			    }
		     $	    {send_user "The date is [exec date]."}
		     \003   exit
		     foo    {send_user "bar"}
		     ~~
		 }

	     In	 string-body  pairs, strings are matched in the order they are
	     listed as arguments.  Strings that partially match are  not  sent
	     to	 the  current process in anticipation of the remainder coming.
	     If characters are then entered such that there can no longer pos‐
	     sibly be a match, only the part of the string will be sent to the
	     process that cannot possibly begin another match.	Thus,  strings
	     that  are	substrings  of partial matches can match later, if the
	     original strings that  was	 attempting  to	 be  match  ultimately
	     fails.

	     By	 default,  string  matching  is exact with no wild cards.  (In
	     contrast,	the  expect  command  uses  glob-style	 patterns   by
	     default.)	 The  -ex  flag	 may  be used to protect patterns that
	     might otherwise match interact flags from doing so.  Any  pattern
	     beginning	with  a	 "-"  should  be  protected  this way.	  (All
	     strings starting with "-" are reserved for future options.)

	     The -re flag forces the string to be  interpreted	as  a  regexp-
	     style  pattern.   In this case, matching substrings are stored in
	     the variable interact_out similarly to the way expect stores  its
	     output  in	 the  variable expect_out.  The -indices flag is simi‐
	     larly supported.

	     The pattern eof introduces an action that is executed  upon  end-
	     of-file.  A separate eof pattern may also follow the -output flag
	     in which case it is matched if an eof is detected	while  writing
	     output.   The  default  eof  action is "return", so that interact
	     simply returns upon any EOF.

	     The pattern timeout introduces a timeout (in seconds) and	action
	     that  is  executed after no characters have been read for a given
	     time.  The timeout pattern applies to the most recently specified
	     process.	There  is  no  default	timeout.  The special variable
	     "timeout" (used by the expect command)  has  no  affect  on  this
	     timeout.

	     For  example, the following statement could be used to autologout
	     users who have not typed anything for an hour but who  still  get
	     frequent system messages:

		 interact -input $user_spawn_id timeout 3600 return -output \
		     $spawn_id

	     If	 the  pattern  is the keyword null, and nulls are allowed (via
	     the remove_nulls command), the corresponding body is executed  if
	     a single ASCII 0 is matched.  It is not possible to match 0 bytes
	     via glob or regexp patterns.

	     Prefacing a pattern with the flag	-iwrite	 causes	 the  variable
	     interact_out(spawn_id)  to	 be  set to the spawn_id which matched
	     the pattern (or eof).

	     Actions such as  break  and  continue  cause  control  structures
	     (i.e.,  for,  proc)  to  behave in the usual way.	However return
	     causes interact to	 return	 to  its  caller,  while  inter_return
	     causes interact to cause a return in its caller.  For example, if
	     "proc  foo"  called  interact  which  then	 executed  the	action
	     inter_return,  proc foo would return.  (This means that if inter‐
	     act calls interpreter interactively typing return will cause  the
	     interact  to continue, while inter_return will cause the interact
	     to return to its caller.)

	     During interact, raw mode is used so that all characters  may  be
	     passed  to	 the current process.  If the current process does not
	     catch job control signals, it will stop if sent a stop signal (by
	     default  ^Z).   To restart it, send a continue signal (such as by
	     "kill -CONT <pid>").  If you really want to  send	a  SIGSTOP  to
	     such a process (by ^Z), consider spawning csh first and then run‐
	     ning your program.	 On the other hand, if	you  want  to  send  a
	     SIGSTOP  to  Expect itself, first press the escape character, and
	     then press ^Z.

	     String-body pairs can be used as a shorthand for avoiding	having
	     to enter the interpreter and execute commands interactively.  The
	     previous terminal mode is used while the body  of	a  string-body
	     pair is being executed.

	     For  speed,  actions  execute in raw mode by default.  The -reset
	     flag resets the terminal to the mode it had before	 interact  was
	     executed (invariably, cooked mode).  Note that characters entered
	     when the mode is being switched may be lost (an unfortunate  fea‐
	     ture of the terminal driver on some systems).  The only reason to
	     use -reset is if your action depends on running in cooked mode.

	     The -echo flag sends characters that match the following  pattern
	     back  to  the  process  that  generated them as each character is
	     read.  This may be useful when the user  needs  to	 see  feedback
	     from partially typed patterns.

	     If	 a  pattern is being echoed but eventually fails to match, the
	     characters are sent to  the  spawned  process.   If  the  spawned
	     process then echoes them, the user will see the characters twice.
	     -echo is probably only appropriate in situations where  the  user
	     is	 unlikely  to not complete the pattern.	 For example, the fol‐
	     lowing excerpt is from rftp, the recursive-ftp script, where  the
	     user is prompted to enter ~g, ~p, or ~l, to get, put, or list the
	     current directory recursively.  These are so far  away  from  the
	     normal ftp commands, that the user is unlikely to type ~ followed
	     by anything else, except mistakenly, in which case, they'll prob‐
	     ably just ignore the result anyway.

		 interact {
		     -echo ~g {getcurdirectory 1}
		     -echo ~l {getcurdirectory 0}
		     -echo ~p {putcurdirectory}
		 }

	     The -nobuffer flag sends characters that match the following pat‐
	     tern on to the output process as characters are read.

	     This is useful when you wish to let a program echo back the  pat‐
	     tern.   For example, the following might be used to monitor where
	     a person is dialing (a Hayes-style modem).	 Each  time  "atd"  is
	     seen the script logs the rest of the line.

		 proc lognumber {} {
		     interact -nobuffer -re "(.*)\r" return
		     puts $log "[exec date]: dialed $interact_out(1,string)"
		 }

		 interact -nobuffer "atd" lognumber

	     During interact, previous use of log_user is ignored.  In partic‐
	     ular, interact will force its output to be logged	(sent  to  the
	     standard  output)	since  it is presumed the user doesn't wish to
	     interact blindly.

	     The -o flag causes any following key-body pairs to be applied  to
	     the output of the current process.	 This can be useful, for exam‐
	     ple, when dealing with hosts that send unwanted characters during
	     a telnet session.

	     By	 default,  interact  expects  the user to be writing stdin and
	     reading stdout of the Expect process itself.  The	-u  flag  (for
	     "user")  makes interact look for the user as the process named by
	     its argument (which must be a spawned id).

	     This allows two unrelated processes to be joined together without
	     using  an explicit loop.  To aid in debugging, Expect diagnostics
	     always go to stderr (or stdout for certain logging and  debugging
	     information).   For the same reason, the interpreter command will
	     read interactively from stdin.

	     For example, the following	 fragment  creates  a  login  process.
	     Then  it dials the user (not shown), and finally connects the two
	     together.	Of course, any process may be substituted  for	login.
	     A	shell,	for example, would allow the user to work without sup‐
	     plying an account and password.

		 spawn login
		 set login $spawn_id
		 spawn tip modem
		 # dial back out to user
		 # connect user to login
		 interact -u $login

	     To send output to multiple processes, list	 each  spawn  id  list
	     prefaced  by  a  -output flag.  Input for a group of output spawn
	     ids may be determined by a spawn id list  prefaced	 by  a	-input
	     flag.   (Both  -input and -output may take lists in the same form
	     as the -i flag in the expect command, except that any_spawn_id is
	     not meaningful in interact.)  All following flags and strings (or
	     patterns) apply to this input until another -input flag  appears.
	     If	 no  -input  appears,  -output	implies "-input $user_spawn_id
	     -output".	(Similarly, with patterns that do  not	have  -input.)
	     If	 one  -input  is specified, it overrides $user_spawn_id.  If a
	     second -input is specified, it overrides  $spawn_id.   Additional
	     -input flags may be specified.

	     The  two  implied input processes default to having their outputs
	     specified as $spawn_id and $user_spawn_id	(in  reverse).	 If  a
	     -input  flag  appears  with no -output flag, characters from that
	     process are discarded.

	     The -i flag introduces a replacement  for	the  current  spawn_id
	     when  no  other  -input  or  -output  flags  are used.  A -i flag
	     implies a -o flag.

	     It is possible to change the processes that are being  interacted
	     with  by  using  indirect	spawn  ids.   (Indirect	 spawn ids are
	     described in the section on the expect command.)  Indirect	 spawn
	     ids may be specified with the -i, -u, -input, or -output flags.

       interpreter
	     causes  the  user to be interactively prompted for Expect and Tcl
	     commands.	The result of each command is printed.

	     Actions such as  break  and  continue  cause  control  structures
	     (i.e.,  for,  proc)  to  behave in the usual way.	However return
	     causes interpreter to return to its  caller,  while  inter_return
	     causes interpreter to cause a return in its caller.  For example,
	     if "proc foo" called interpreter which then executed  the	action
	     inter_return,  proc  foo  would return.  Any other command causes
	     interpreter to continue prompting for new commands.

	     By default, the prompt contains two integers.  The first  integer
	     describes the depth of the evaluation stack (i.e., how many times
	     Tcl_Eval has been called).	 The second integer is the Tcl history
	     identifier.  The prompt can be set by defining a procedure called
	     "prompt1" whose return value  becomes  the	 next  prompt.	 If  a
	     statement	has  open  quotes, parens, braces, or brackets, a sec‐
	     ondary prompt (by default "+> ") is  issued  upon	newline.   The
	     secondary	prompt	may  be	 set  by  defining  a procedure called
	     "prompt2".

	     During interpreter, cooked mode is used, even if the  its	caller
	     was using raw mode.

       log_file [args] [[-a] file]
	     If	 a  filename is provided, log_file will record a transcript of
	     the session (beginning at that point) in the file.	 log_file will
	     stop recording if no argument is given.  Any previous log file is
	     closed.

	     Instead of a filename, a Tcl file identifier may be  provided  by
	     using  the	 -open	or  -leaveopen	flags.	This is similar to the
	     spawn command.  (See spawn for more info.)

	     The -a flag forces output to be logged that was suppressed by the
	     log_user command.

	     By default, the log_file command appends to old files rather than
	     truncating them, for the convenience of being able to  turn  log‐
	     ging  off	and  on	 multiple  times  in one session.  To truncate
	     files, use the -noappend flag.

	     The -info flag causes log_file to return  a  description  of  the
	     most recent non-info arguments given.

       log_user -info|0|1
	     By	 default,  the send/expect dialogue is logged to stdout (and a
	     logfile if open).	The logging to stdout is disabled by the  com‐
	     mand  "log_user 0" and reenabled by "log_user 1".	Logging to the
	     logfile is unchanged.

	     The -info flag causes log_user to return  a  description  of  the
	     most recent non-info arguments given.

       match_max [-d] [-i spawn_id] [size]
	     defines  the  size	 of  the  buffer (in bytes) used internally by
	     expect.  With no size argument, the current size is returned.

	     With the -d flag, the default size is set.	 (The initial  default
	     is	 2000.)	 With the -i flag, the size is set for the named spawn
	     id, otherwise it is set for the current process.

       overlay [-# spawn_id] [-# spawn_id] [...] program [args]
	     executes program args in place of	the  current  Expect  program,
	     which  terminates.	  A  bare  hyphen  argument forces a hyphen in
	     front of the command name as  if  it  was	a  login  shell.   All
	     spawn_ids	are closed except for those named as arguments.	 These
	     are mapped onto the named file identifiers.

	     Spawn_ids are mapped to file identifiers for the new  program  to
	     inherit.	For  example, the following line runs chess and allows
	     it to be controlled by the current process - say, a chess master.

		 overlay -0 $spawn_id -1 $spawn_id -2 $spawn_id chess

	     This is more efficient than "interact -u", however, it sacrifices
	     the ability to do programmed interaction since the Expect process
	     is no longer in control.

	     Note that no controlling terminal is provided.  Thus, if you dis‐
	     connect  or  remap	 standard  input, programs that do job control
	     (shells, login, etc) will not function properly.

       parity [-d] [-i spawn_id] [value]
	     defines whether parity should be retained or  stripped  from  the
	     output  of	 spawned  processes.   If  value  is  zero,  parity is
	     stripped, otherwise it is not stripped.  With no value  argument,
	     the current value is returned.

	     With  the -d flag, the default parity value is set.  (The initial
	     default is 1, i.e., parity is not stripped.)  With the  -i	 flag,
	     the  parity  value is set for the named spawn id, otherwise it is
	     set for the current process.

       remove_nulls [-d] [-i spawn_id] [value]
	     defines whether nulls are retained or removed from the output  of
	     spawned processes before pattern matching or storing in the vari‐
	     able expect_out or	 interact_out.	 If  value  is	1,  nulls  are
	     removed.	If  value  is 0, nulls are not removed.	 With no value
	     argument, the current value is returned.

	     With the -d flag, the default value is set.  (The initial default
	     is	 1,  i.e., nulls are removed.)	With the -i flag, the value is
	     set for the named spawn id, otherwise it is set for  the  current
	     process.

	     Whether  or  not nulls are removed, Expect will record null bytes
	     to the log and stdout.

       send [-flags] string
	     Sends string to the current process.  For example, the command

		 send "hello world\r"

	     sends the characters, h e l l o <blank> w o r l d <return> to the
	     current  process.	 (Tcl  includes	 a printf-like command (called
	     format) which can build arbitrarily complex strings.)

	     Characters are sent  immediately  although	 programs  with	 line-
	     buffered  input will not read the characters until a return char‐
	     acter is sent.  A return character is denoted "\r".

	     The -- flag forces the next  argument  to	be  interpreted	 as  a
	     string  rather  than  a flag.  Any string can be preceded by "--"
	     whether or not it actually looks like a flag.   This  provides  a
	     reliable  mechanism  to  specify  variable	 strings without being
	     tripped up by those that  accidentally  look  like	 flags.	  (All
	     strings starting with "-" are reserved for future options.)

	     The  -i  flag  declares  that  the	 string	 be  sent to the named
	     spawn_id.	If the spawn_id is user_spawn_id, and the terminal  is
	     in raw mode, newlines in the string are translated to return-new‐
	     line sequences so that they appear as  it	the  terminal  was  in
	     cooked mode.  The -raw flag disables this translation.

	     The  -null flag sends null characters (0 bytes).  By default, one
	     null is sent.  An integer may follow the -null  to	 indicate  how
	     many nulls to send.

	     The  -break  flag	generates  a break condition.  This only makes
	     sense if the spawn id refers to a tty device  opened  via	"spawn
	     -open".   If  you	have spawned a process such as tip, you should
	     use tip's convention for generating a break.

	     The -s flag forces output to be sent  "slowly",  thus  avoid  the
	     common  situation	where a computer outtypes an input buffer that
	     was designed for a human who would never outtype the same buffer.
	     This   output   is	 controlled  by	 the  value  of	 the  variable
	     "send_slow" which takes a two element list.  The first element is
	     an integer that describes the number of bytes to send atomically.
	     The second element is a real number that describes the number  of
	     seconds  by  which the atomic sends must be separated.  For exam‐
	     ple, "set send_slow {10 .001}" would  force  "send	 -s"  to  send
	     strings with 1 millisecond in between each 10 characters sent.

	     The  -h  flag  forces  output  to be sent (somewhat) like a human
	     actually typing.  Human-like delays appear	 between  the  charac‐
	     ters.   (The algorithm is based upon a Weibull distribution, with
	     modifications to suit this particular application.)  This	output
	     is	 controlled  by	 the  value of the variable "send_human" which
	     takes a five element list.	 The first two	elements  are  average
	     interarrival time of characters in seconds.  The first is used by
	     default.  The second is used at word  endings,  to	 simulate  the
	     subtle  pauses  that occasionally occur at such transitions.  The
	     third parameter is a measure of variability  where	 .1  is	 quite
	     variable,	1  is reasonably variable, and 10 is quite invariable.
	     The extremes are 0 to infinity.  The  last	 two  parameters  are,
	     respectively, a minimum and maximum interarrival time.  The mini‐
	     mum and maximum are used last and "clip"  the  final  time.   The
	     ultimate average can be quite different from the given average if
	     the minimum and maximum clip enough values.

	     As an example, the following command emulates a fast and  consis‐
	     tent typist:

		 set send_human {.1 .3 1 .05 2}
		 send -h "I'm hungry.  Let's do lunch."

	     while the following might be more suitable after a hangover:

		 set send_human {.4 .4 .2 .5 100}
		 send -h "Goodd party lash night!"

	     Note that errors are not simulated, although you can set up error
	     correction situations yourself by embedding mistakes and  correc‐
	     tions in a send argument.

	     The  flags	 for  sending null characters, for sending breaks, for
	     forcing slow output  and  for  human-style	 output	 are  mutually
	     exclusive. Only the one specified last will be used. Furthermore,
	     no string argument can be specified with the  flags  for  sending
	     null characters or breaks.

	     It	 is  a	good idea to precede the first send to a process by an
	     expect.  expect will wait for the process to  start,  while  send
	     cannot.   In  particular,	if the first send completes before the
	     process starts running, you run the  risk	of  having  your  data
	     ignored.	In situations where interactive programs offer no ini‐
	     tial prompt, you can precede send by a delay as in:

		 # To avoid giving hackers hints on how to break in,
		 # this system does not prompt for an external password.
		 # Wait for 5 seconds for exec to complete
		 spawn telnet very.secure.gov
		 sleep 5
		 send password\r

	     exp_send is an alias for send.  If you are using Expectk or  some
	     other variant of Expect in the Tk environment, send is defined by
	     Tk for an entirely different purpose.  exp_send is	 provided  for
	     compatibility between environments.  Similar aliases are provided
	     for other Expect's other send commands.

       send_error [-flags] string
	     is like send, except that the output is  sent  to	stderr	rather
	     than the current process.

       send_log [--] string
	     is like send, except that the string is only sent to the log file
	     (see log_file.)  The arguments are ignored	 if  no	 log  file  is
	     open.

       send_tty [-flags] string
	     is	 like  send, except that the output is sent to /dev/tty rather
	     than the current process.

       send_user [-flags] string
	     is like send, except that the output is  sent  to	stdout	rather
	     than the current process.

       sleep seconds
	     causes the script to sleep for the given number of seconds.  Sec‐
	     onds may be a decimal number.  Interrupts (and Tk events  if  you
	     are using Expectk) are processed while Expect sleeps.

       spawn [args] program [args]
	     creates  a	 new  process running program args.  Its stdin, stdout
	     and stderr are connected to Expect, so that they may be read  and
	     written  by  other	 Expect commands.  The connection is broken by
	     close or if the process itself closes any	of  the	 file  identi‐
	     fiers.

	     When  a process is started by spawn, the variable spawn_id is set
	     to a descriptor referring to that process.	 The process described
	     by	 spawn_id  is considered the current process.  spawn_id may be
	     read or written, in effect providing job control.

	     user_spawn_id is a global variable containing a descriptor	 which
	     refers  to	 the  user.  For example, when spawn_id is set to this
	     value, expect behaves like expect_user.

	     error_spawn_id is a global variable containing a descriptor which
	     refers  to the standard error.  For example, when spawn_id is set
	     to this value, send behaves like send_error.

	     tty_spawn_id is a global variable containing a  descriptor	 which
	     refers  to	 /dev/tty.   If	 /dev/tty does not exist (such as in a
	     cron, at, or batch script), then  tty_spawn_id  is	 not  defined.
	     This may be tested as:

		 if [info vars tty_spawn_id] {
		     # /dev/tty exists
		 } else {
		     # /dev/tty doesn't exist
		     # probably in cron, batch, or at script
		 }

	     spawn  returns  the UNIX process id.  If no process is spawned, 0
	     is returned.  The variable spawn_out(slave,name) is  set  to  the
	     name of the pty slave device.

	     By	 default,  spawn  echoes  the command name and arguments.  The
	     -noecho flag stops spawn from doing this.

	     The -console flag causes console output to be redirected  to  the
	     spawned process.  This is not supported on all systems.

	     Internally,  spawn	 uses  a  pty, initialized the same way as the
	     user's tty.  This is further initialized so that all settings are
	     "sane"  (according	 to  stty(1)).	 If  the variable stty_init is
	     defined, it is interpreted in the style of stty arguments as fur‐
	     ther  configuration.  For example, "set stty_init raw" will cause
	     further spawned processes's  terminals  to	 start	in  raw	 mode.
	     -nottycopy	 skips	the  initialization  based  on the user's tty.
	     -nottyinit skips the "sane" initialization.

	     Normally, spawn takes little time	to  execute.   If  you	notice
	     spawn taking a significant amount of time, it is probably encoun‐
	     tering ptys that are wedged.  A number of tests are run  on  ptys
	     to	 avoid	entanglements  with  errant processes.	(These take 10
	     seconds per wedged pty.)  Running Expect with the -d option  will
	     show  if  Expect is encountering many ptys in odd states.	If you
	     cannot kill the processes to which these ptys are attached,  your
	     only recourse may be to reboot.

	     If	 program  cannot be spawned successfully because exec(2) fails
	     (e.g. when program doesn't	 exist),  an  error  message  will  be
	     returned by the next interact or expect command as if program had
	     run and produced the error message as output.  This behavior is a
	     natural  consequence of the implementation of spawn.  Internally,
	     spawn forks, after which the spawned process has no way to commu‐
	     nicate  with  the original Expect process except by communication
	     via the spawn_id.

	     The -open flag causes the next argument to be  interpreted	 as  a
	     Tcl  file	identifier (i.e., returned by open.)  The spawn id can
	     then be used as if it were a spawned process.  (The file  identi‐
	     fier should no longer be used.)  This lets you treat raw devices,
	     files, and pipelines as spawned processes without using a pty.  0
	     is returned to indicate there is no associated process.  When the
	     connection to the spawned process is closed, so is the  Tcl  file
	     identifier.   The -leaveopen flag is similar to -open except that
	     -leaveopen causes the file identifier to be left open even	 after
	     the spawn id is closed.

	     The  -pty	flag causes a pty to be opened but no process spawned.
	     0 is  returned  to	 indicate  there  is  no  associated  process.
	     Spawn_id is set as usual.

	     The variable spawn_out(slave,fd) is set to a file identifier cor‐
	     responding to the pty slave.   It	can  be	 closed	 using	"close
	     -slave".

	     The  -ignore  flag	 names	a  signal to be ignored in the spawned
	     process.  Otherwise, signals get the default  behavior.   Signals
	     are  named	 as  in	 the  trap  command,  except  that each signal
	     requires a separate flag.

       strace level
	     causes following statements to be printed before being  executed.
	     (Tcl's  trace command traces variables.)  level indicates how far
	     down in the call stack to trace.  For example, the following com‐
	     mand  runs	 Expect while tracing the first 4 levels of calls, but
	     none below that.

		 expect -c "strace 4" script.exp

	     The -info flag causes strace to return a description of the  most
	     recent non-info arguments given.

       stty args
	     changes terminal modes similarly to the external stty command.

	     By	 default,  the controlling terminal is accessed.  Other termi‐
	     nals can be accessed by appending "< /dev/tty..." to the command.
	     (Note  that  the  arguments  should  not be grouped into a single
	     argument.)

	     Requests for status return it as the result of the	 command.   If
	     no	 status is requested and the controlling terminal is accessed,
	     the previous status of the raw and echo attributes	 are  returned
	     in a form which can later be used by the command.

	     For  example,  the arguments raw or -cooked put the terminal into
	     raw mode.	The arguments -raw or cooked  put  the	terminal  into
	     cooked  mode.  The arguments echo and -echo put the terminal into
	     echo and noecho mode respectively.

	     The following example  illustrates	 how  to  temporarily  disable
	     echoing.	This  could  be used in otherwise-automatic scripts to
	     avoid embedding passwords in them.	 (See more discussion on  this
	     under EXPECT HINTS below.)

		 stty -echo
		 send_user "Password: "
		 expect_user -re "(.*)\n"
		 set password $expect_out(1,string)
		 stty echo

       system args
	     gives  args  to sh(1) as input, just as if it had been typed as a
	     command from a terminal.  Expect waits  until  the	 shell	termi‐
	     nates.   The  return  status from sh is handled the same way that
	     exec handles its return status.

	     In contrast to exec which	redirects  stdin  and  stdout  to  the
	     script, system performs no redirection (other than that indicated
	     by the string itself).  Thus, it  is  possible  to	 use  programs
	     which  must  talk directly to /dev/tty.  For the same reason, the
	     results of system are not recorded in the log.

       timestamp [args]
	     returns a timestamp.  With no arguments, the  number  of  seconds
	     since the epoch is returned.

	     The  -format  flag introduces a string which is returned but with
	     substitutions made according to the  POSIX	 rules	for  strftime.
	     For  example %a is replaced by an abbreviated weekday name (i.e.,
	     Sat).  Others are:
		 %a	 abbreviated weekday name
		 %A	 full weekday name
		 %b	 abbreviated month name
		 %B	 full month name
		 %c	 date-time as in: Wed Oct  6 11:45:56 1993
		 %d	 day of the month (01-31)
		 %H	 hour (00-23)
		 %I	 hour (01-12)
		 %j	 day (001-366)
		 %m	 month (01-12)
		 %M	 minute (00-59)
		 %p	 am or pm
		 %S	 second (00-61)
		 %u	 day (1-7, Monday is first day of week)
		 %U	 week (00-53, first Sunday is first day of week one)
		 %V	 week (01-53, ISO 8601 style)
		 %w	 day (0-6)
		 %W	 week (00-53, first Monday is first day of week one)
		 %x	 date-time as in: Wed Oct  6 1993
		 %X	 time as in: 23:59:59
		 %y	 year (00-99)
		 %Y	 year as in: 1993
		 %Z	 timezone (or nothing if not determinable)
		 %%	 a bare percent sign

	     Other % specifications are undefined.  Other characters  will  be
	     passed through untouched.	Only the C locale is supported.

	     The  -seconds flag introduces a number of seconds since the epoch
	     to be used as a source from which to format.  Otherwise, the cur‐
	     rent time is used.

	     The  -gmt	flag  forces timestamp output to use the GMT timezone.
	     With no flag, the local timezone is used.

       trap [[command] signals]
	     causes the given command to be executed upon  future  receipt  of
	     any  of the given signals.	 The command is executed in the global
	     scope.  If command is absent, the signal action is returned.   If
	     command  is the string SIG_IGN, the signals are ignored.  If com‐
	     mand is the string SIG_DFL, the signals are result to the	system
	     default.  signals is either a single signal or a list of signals.
	     Signals may be specified numerically or symbolically as per  sig‐
	     nal(3).  The "SIG" prefix may be omitted.

	     With  no  arguments  (or  the argument -number), trap returns the
	     signal number of the trap command currently being executed.

	     The -code flag uses the return code of the command	 in  place  of
	     whatever code Tcl was about to return when the command originally
	     started running.

	     The -interp flag causes the command to  be	 evaluated  using  the
	     interpreter active at the time the command started running rather
	     than when the trap was declared.

	     The -name flag causes the trap command to return the signal  name
	     of the trap command currently being executed.

	     The  -max flag causes the trap command to return the largest sig‐
	     nal number that can be set.

	     For example, the command "trap {send_user "Ouch!"}	 SIGINT"  will
	     print "Ouch!"  each time the user presses ^C.

	     By	 default,  SIGINT  (which can usually be generated by pressing
	     ^C) and SIGTERM cause Expect to exit.  This is due to the follow‐
	     ing trap, created by default when Expect starts.

		 trap exit {SIGINT SIGTERM}

	     If you use the -D flag to start the debugger, SIGINT is redefined
	     to start the interactive debugger.	 This is due to the  following
	     trap:

		 trap {exp_debug 1} SIGINT

	     The debugger trap can be changed by setting the environment vari‐
	     able EXPECT_DEBUG_INIT to a new trap command.

	     You can, of course, override both of these just  by  adding  trap
	     commands  to  your	 script.   In particular, if you have your own
	     "trap exit SIGINT", this will override the debugger  trap.	  This
	     is useful if you want to prevent users from getting to the debug‐
	     ger at all.

	     If you want to define your own trap on SIGINT but still  trap  to
	     the debugger when it is running, use:

		 if ![exp_debug] {trap mystuff SIGINT}

	     Alternatively, you can trap to the debugger using some other sig‐
	     nal.

	     trap will not let you override the action for SIGALRM as this  is
	     used  internally  to Expect.  The disconnect command sets SIGALRM
	     to SIG_IGN (ignore).  You can reenable this as long as  you  dis‐
	     able it during subsequent spawn commands.

	     See signal(3) for more info.

       wait [args]
	     delays until a spawned process (or the current process if none is
	     named) terminates.

	     wait normally returns a list of four integers.  The first integer
	     is the pid of the process that was waited upon.  The second inte‐
	     ger is the corresponding spawn id.	 The third integer is -1 if an
	     operating	system	error  occurred, or 0 otherwise.  If the third
	     integer was 0, the fourth integer is the status returned  by  the
	     spawned process.  If the third integer was -1, the fourth integer
	     is the value of errno set by the operating	 system.   The	global
	     variable errorCode is also set.

	     Additional	 elements  may	appear	at the end of the return value
	     from wait.	 An optional  fifth  element  identifies  a  class  of
	     information.  Currently, the only possible value for this element
	     is CHILDKILLED in which case the next two values are the  C-style
	     signal name and a short textual description.

	     The  -i  flag  declares  the process to wait corresponding to the
	     named spawn_id (NOT the process id).  Inside a  SIGCHLD  handler,
	     it is possible to wait for any spawned process by using the spawn
	     id -1.

	     The -nowait flag causes the wait to return immediately  with  the
	     indication of a successful wait.  When the process exits (later),
	     it will automatically disappear without the need for an  explicit
	     wait.

	     The wait command may also be used wait for a forked process using
	     the arguments "-i -1".  Unlike its use  with  spawned  processes,
	     this  command  can	 be executed at any time.  There is no control
	     over which process is reaped.  However, the return value  can  be
	     checked for the process id.

LIBRARIES
       Expect  automatically  knows  about  two	 built-in libraries for Expect
       scripts.	 These are defined by the directories named in	the  variables
       exp_library  and	 exp_exec_library.   Both are meant to contain utility
       files that can be used by other scripts.

       exp_library contains architecture-independent files.   exp_exec_library
       contains	 architecture-dependent files.	Depending on your system, both
       directories  may	 be  totally  empty.   The  existence  of   the	  file
       $exp_exec_library/cat-buffers  describes	 whether your /bin/cat buffers
       by default.

PRETTY-PRINTING
       A vgrind definition is available for  pretty-printing  Expect  scripts.
       Assuming the vgrind definition supplied with the Expect distribution is
       correctly installed, you can use it as:

	   vgrind -lexpect file

EXAMPLES
       It many not be apparent how to put everything  together	that  the  man
       page  describes.	  I  encourage you to read and try out the examples in
       the example directory of the Expect distribution.   Some	 of  them  are
       real  programs.	 Others are simply illustrative of certain techniques,
       and of course, a couple are just quick hacks.  The INSTALL file	has  a
       quick overview of these programs.

       The  Expect  papers  (see SEE ALSO) are also useful.  While some papers
       use syntax corresponding to earlier versions of Expect, the  accompany‐
       ing  rationales are still valid and go into a lot more detail than this
       man page.

CAVEATS
       Extensions may collide with Expect's command names.  For example,  send
       is  defined  by Tk for an entirely different purpose.  For this reason,
       most of the Expect commands are also available as "exp_XXXX".  Commands
       and  variables beginning with "exp", "inter", "spawn", and "timeout" do
       not have aliases.  Use the extended command names if you need this com‐
       patibility between environments.

       Expect  takes  a	 rather liberal view of scoping.  In particular, vari‐
       ables read by commands specific to the Expect program  will  be	sought
       first from the local scope, and if not found, in the global scope.  For
       example, this obviates the need to place "global timeout" in every pro‐
       cedure  you write that uses expect.  On the other hand, variables writ‐
       ten are always in the local scope (unless a "global" command  has  been
       issued).	 The most common problem this causes is when spawn is executed
       in a procedure.	Outside the procedure, spawn_id no longer  exists,  so
       the  spawned process is no longer accessible simply because of scoping.
       Add a "global spawn_id" to such a procedure.

       If you cannot enable the multispawning capability  (i.e.,  your	system
       supports	 neither select (BSD *.*), poll (SVR>2), nor something equiva‐
       lent), Expect will only be able to control a single process at a	 time.
       In  this	 case,	do not attempt to set spawn_id, nor should you execute
       processes via exec while a spawned process  is  running.	  Furthermore,
       you  will  not be able to expect from multiple processes (including the
       user as one) at the same time.

       Terminal parameters can have a big effect on scripts.  For example,  if
       a  script  is written to look for echoing, it will misbehave if echoing
       is turned off.  For this reason, Expect forces sane terminal parameters
       by  default.   Unfortunately, this can make things unpleasant for other
       programs.  As an example, the emacs shell wants to change  the  "usual"
       mappings:  newlines  get	 mapped to newlines instead of carriage-return
       newlines, and echoing is disabled.  This allows one  to	use  emacs  to
       edit the input line.  Unfortunately, Expect cannot possibly guess this.

       You  can request that Expect not override its default setting of termi‐
       nal parameters, but you must then be very careful when writing  scripts
       for  such  environments.	  In  the  case of emacs, avoid depending upon
       things like echoing and end-of-line mappings.

       The commands that accepted arguments braced into	 a  single  list  (the
       expect  variants and interact) use a heuristic to decide if the list is
       actually one argument or many.  The heuristic can fail only in the case
       when  the list actually does represent a single argument which has mul‐
       tiple embedded \n's with non-whitespace characters between them.	  This
       seems  sufficiently  improbable,	 however  the argument "-brace" can be
       used to force a single argument to be handled  as  a  single  argument.
       This could conceivably be used with machine-generated Expect code.

BUGS
       It  was	really	tempting  to name the program "sex" (for either "Smart
       EXec" or "Send-EXpect"), but good sense (or  perhaps  just  Puritanism)
       prevailed.

       On  some systems, when a shell is spawned, it complains about not being
       able to access the tty but runs anyway.	This means your system	has  a
       mechanism  for  gaining	the  controlling  tty that Expect doesn't know
       about.  Please find out what it is, and send this information  back  to
       me.

       Ultrix  4.1  (at least the latest versions around here) considers time‐
       outs of above 1000000 to be equivalent to 0.

       Digital UNIX 4.0A (and probably other  versions)	 refuses  to  allocate
       ptys if you define a SIGCHLD handler.  See grantpt page for more info.

       IRIX  6.0  does	not handle pty permissions correctly so that if Expect
       attempts to allocate a pty previously used by someone else,  it	fails.
       Upgrade to IRIX 6.1.

       Telnet  (verified  only	under  SunOS  4.1.2) hangs if TERM is not set.
       This is a problem under cron, at and  in	 cgi  scripts,	which  do  not
       define  TERM.   Thus, you must set it explicitly - to what type is usu‐
       ally irrelevant.	 It just has to be set to  something!	The  following
       probably suffices for most cases.

	   set env(TERM) vt100

       Tip  (verified only under BSDI BSD/OS 3.1 i386) hangs if SHELL and HOME
       are not set.  This is a problem under cron,  at	and  in	 cgi  scripts,
       which  do  not  define these environment variables.  Thus, you must set
       them explicitly - to what type is usually irrelevant.  It just  has  to
       be set to something!  The following probably suffices for most cases.

	   set env(SHELL) /bin/sh
	   set env(HOME) /usr/local/bin

       Some  implementations  of  ptys	are designed so that the kernel throws
       away any unread output after 10 to 15 seconds (actual number is	imple‐
       mentation-dependent)  after the process has closed the file descriptor.
       Thus Expect programs such as

	   spawn date
	   sleep 20
	   expect

       will fail.  To avoid this, invoke non-interactive  programs  with  exec
       rather  than spawn.  While such situations are conceivable, in practice
       I have never encountered a situation in which the  final	 output	 of  a
       truly interactive program would be lost due to this behavior.

       On  the other hand, Cray UNICOS ptys throw away any unread output imme‐
       diately after the process has  closed  the  file	 descriptor.   I  have
       reported this to Cray and they are working on a fix.

       Sometimes  a delay is required between a prompt and a response, such as
       when a tty interface is changing UART settings or matching  baud	 rates
       by  looking  for	 start/stop  bits.  Usually, all this is require is to
       sleep for a second or two.  A more robust technique is to  retry	 until
       the  hardware  is  ready	 to receive input.  The following example uses
       both strategies:

	   send "speed 9600\r";
	   sleep 1
	   expect {
	       timeout {send "\r"; exp_continue}
	       $prompt
	   }

EXPECT HINTS
       There are a couple of things about Expect that  may  be	non-intuitive.
       This  section attempts to address some of these things with a couple of
       suggestions.

       A common expect problem is how to recognize shell prompts.  Since these
       are  customized differently by differently people and different shells,
       portably automating rlogin can be difficult without knowing the prompt.
       A  reasonable  convention  is  to have users store a regular expression
       describing their prompt (in particular, the end of it) in the  environ‐
       ment  variable EXPECT_PROMPT.  Code like the following can be used.  If
       EXPECT_PROMPT doesn't exist, the code still has a good chance of	 func‐
       tioning correctly.

	   set prompt "(%|#|\\$) $"	     ;# default prompt
	   catch {set prompt $env(EXPECT_PROMPT)}

	   expect -re $prompt

       I  encourage you to write expect patterns that include the end of what‐
       ever you expect to see.	This avoids the	 possibility  of  answering  a
       question	 before	 seeing	 the entire thing.  In addition, while you may
       well be able to answer questions before seeing them  entirely,  if  you
       answer  early,  your answer may appear echoed back in the middle of the
       question.  In other words, the resulting dialogue will be  correct  but
       look scrambled.

       Most  prompts  include  a space character at the end.  For example, the
       prompt from ftp is 'f', 't', 'p',  '>'  and  <blank>.   To  match  this
       prompt,	you must account for each of these characters.	It is a common
       mistake not to include the blank.  Put the blank in explicitly.

       If you use a pattern of the form X*, the * will match  all  the	output
       received	 from  the  end	 of X to the last thing received.  This sounds
       intuitive but can be somewhat confusing because the phrase "last	 thing
       received"  can  vary  depending	upon the speed of the computer and the
       processing of I/O both by the kernel and the device driver.

       In particular, humans tend to  see  program  output  arriving  in  huge
       chunks  (atomically)  when  in reality most programs produce output one
       line at a time.	Assuming this is the case, the * in the pattern of the
       previous	 paragraph  may	 only  match  the end of the current line even
       though there seems to be more, because at the time of  the  match  that
       was all the output that had been received.

       expect  has no way of knowing that further output is coming unless your
       pattern specifically accounts for it.

       Even depending on line-oriented buffering is unwise.  Not only do  pro‐
       grams  rarely  make  promises  about the type of buffering they do, but
       system indigestion can break output lines up so	that  lines  break  at
       seemingly random places.	 Thus, if you can express the last few charac‐
       ters of a prompt when writing patterns, it is wise to do so.

       If you are waiting for a pattern in the last output of  a  program  and
       the  program  emits  something  else  instead,  you will not be able to
       detect that with the timeout keyword.  The reason is that  expect  will
       not timeout - instead it will get an eof indication.  Use that instead.
       Even better, use both.  That way if that line is ever moved around, you
       won't have to edit the line itself.

       Newlines	 are  usually converted to carriage return, linefeed sequences
       when output by the terminal driver.  Thus, if you want a	 pattern  that
       explicitly  matches  the	 two lines, from, say, printf("foo\nbar"), you
       should use the pattern "foo\r\nbar".

       A  similar  translation	occurs	when  reading  from  the   user,   via
       expect_user.   In  this	case, when you press return, it will be trans‐
       lated to a newline.  If Expect then passes that to a program which sets
       its terminal to raw mode (like telnet), there is going to be a problem,
       as the program expects a true return.  (Some programs are actually for‐
       giving  in  that they will automatically translate newlines to returns,
       but most don't.)	 Unfortunately, there is no way to  find  out  that  a
       program put its terminal into raw mode.

       Rather  than  manually replacing newlines with returns, the solution is
       to use the command "stty raw", which will stop the translation.	 Note,
       however,	 that  this means that you will no longer get the cooked line-
       editing features.

       interact implicitly sets your terminal to raw mode so this problem will
       not arise then.

       It is often useful to store passwords (or other private information) in
       Expect scripts.	This is not recommended since anything that is	stored
       on a computer is susceptible to being accessed by anyone.  Thus, inter‐
       actively prompting for passwords from a script is a smarter  idea  than
       embedding them literally.  Nonetheless, sometimes such embedding is the
       only possibility.

       Unfortunately, the UNIX file system  has	 no  direct  way  of  creating
       scripts	which  are  executable	but unreadable.	 Systems which support
       setgid shell scripts may indirectly simulate this as follows:

       Create the Expect script (that contains	the  secret  data)  as	usual.
       Make  its permissions be 750 (-rwxr-x---) and owned by a trusted group,
       i.e., a group which is allowed to read it.  If necessary, create a  new
       group for this purpose.	Next, create a /bin/sh script with permissions
       2751 (-rwxr-s--x) owned by the same group as before.

       The result is a script which may be  executed  (and  read)  by  anyone.
       When invoked, it runs the Expect script.

SEE ALSO
       Tcl(3), libexpect(3)
       "Exploring  Expect: A Tcl-Based Toolkit for Automating Interactive Pro‐
       grams" by Don Libes, pp. 602, ISBN 1-56592-090-2,  O'Reilly  and	 Asso‐
       ciates, 1995.
       "expect:	 Curing	 Those	Uncontrollable	Fits  of Interactivity" by Don
       Libes, Proceedings of the Summer 1990 USENIX Conference, Anaheim, Cali‐
       fornia, June 11-15, 1990.
       "Using  expect  to  Automate System Administration Tasks" by Don Libes,
       Proceedings of the 1990 USENIX Large Installation  Systems  Administra‐
       tion Conference, Colorado Springs, Colorado, October 17-19, 1990.
       "Tcl:  An  Embeddable Command Language" by John Ousterhout, Proceedings
       of the Winter 1990 USENIX Conference, Washington, D.C., January	22-26,
       1990.
       "expect:	 Scripts  for  Controlling Interactive Programs" by Don Libes,
       Computing Systems, Vol. 4, No. 2, University of California Press	 Jour‐
       nals, November 1991.
       "Regression  Testing  and Conformance Testing Interactive Programs", by
       Don Libes, Proceedings  of  the	Summer	1992  USENIX  Conference,  pp.
       135-144, San Antonio, TX, June 12-15, 1992.
       "Kibitz	-  Connecting  Multiple Interactive Programs Together", by Don
       Libes, Software - Practice & Experience, John Wiley & Sons,  West  Sus‐
       sex, England, Vol. 23, No. 5, May, 1993.
       "A  Debugger  for  Tcl  Applications", by Don Libes, Proceedings of the
       1993 Tcl/Tk Workshop, Berkeley, CA, June 10-11, 1993.

AUTHOR
       Don Libes, National Institute of Standards and Technology

ACKNOWLEDGMENTS
       Thanks to John Ousterhout for Tcl, and Scott Paisley  for  inspiration.
       Thanks to Rob Savoye for Expect's autoconfiguration code.

       The  HISTORY  file documents much of the evolution of expect.  It makes
       interesting reading and might give you further insight  to  this	 soft‐
       ware.   Thanks  to the people mentioned in it who sent me bug fixes and
       gave other assistance.

       Design and implementation of Expect was paid for in part	 by  the  U.S.
       government  and	is therefore in the public domain.  However the author
       and NIST would like credit if this program and  documentation  or  por‐
       tions of them are used.

			       29 December 1994			     EXPECT(1)
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