Provided by: expect_5.45-2_amd64 bug

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 according 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 structures 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 popularized by uucp, kermit
       and  other  modem control programs.  However unlike uucp, Expect is generalized so that it
       can be run as a user-level command 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,   CompuServe)   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 controlled) 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/bin/expect -f

       Of course, the path must accurately describe where Expect  lives.   /usr/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 executed 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 arbitrary files to be handled this way, use the -b flag.  (When
       using    Expectk,    this    option    is     specified     as     -buffer.)Notethatstdio-
       bufferingmaystilltakeplacehoweverthis shouldn't cause problems when reading from a fifo or
       stdin.

       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 command 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/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 specified 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  corresponding  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  features  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 descriptions 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).  Examples 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 usually 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 explicitly, you should call
             wait to clear up the corresponding kernel process slot.  close does  not  call  wait
             since there is no guarantee 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 running, 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 parameters prior to disconnection, and then later
             apply them to new ptys.  With  &,  Expect  does  not  have  a  chance  to  read  the
             terminal'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  handlers.   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 continue to run.  (A variety of conditions are important to determining, 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 inherited 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 [-continue_timer]
             The command exp_continue allows expect itself  to  continue  executing  rather  than
             returning  as  it  normally would. By default exp_continue resets the timeout timer.
             The -continue_timer flag prevents timer from being restarted. (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  disabled  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_version 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 version 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 implicitly 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 executed upon end-of-
             file.  If a pattern is the keyword timeout, the corresponding body is executed  upon
             timeout.   If  no  timeout keyword 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 patterns 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 buffer.  (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 keyword
             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 pattern, 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 output 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 experimenting (and can be abbreviated to "-not" for convenience
             while experimenting).

             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 automate 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 variable 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  current  expect  to  continue  pattern  matching  after
             executing the current 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  immediately.   Patterns  are
             tested  whenever new input arrives.  The pattern 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  processing  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_background  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 immediately.   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 associated 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 specifications 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  -indirect  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.  keystrokes  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. keystrokes 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 parent
             process, and no child process is created.

             Forked processes exit via the exit command, just like the original 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 keystrokes 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  following  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 [clock format [clock seconds]]."}
                     \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
             possibly 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
             similarly 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 interact 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 running your program.  On  the
             other  hand,  if you want to send a SIGSTOP to Expect itself, first call interpreter
             (perhaps by using an 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 feature 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 following 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 probably 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  pattern  on  to  the
             output process as characters are read.

             This  is  useful when you wish to let a program echo back the pattern.  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 "[clock format [clock seconds]]: dialed $interact_out(1,string)"
                 }

                 interact -nobuffer "atd" lognumber

             During  interact, previous use of log_user is ignored.  In particular, 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 example, 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
             supplying 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  [args]
             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 secondary 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.

             If  stdin  is closed, interpreter will return unless the -eof flag is used, in which
             case the subsequent argument is invoked.

       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 logging 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 command "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  disconnect  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 variable 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 character 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-newline sequences so that they appear as if 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 example, "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 characters.  (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  minimum
             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 consistent 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 corrections 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 initial 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.   Seconds  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
             identifiers.

             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
             further 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 encountering 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 communicate 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 identifier 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  corresponding  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 command 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 terminals 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 terminates.  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 current 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  command  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 signal(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 signal 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 following 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  variable
             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
             debugger 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 signal.

             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 disable 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 integer 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 accompanying 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
       compatibility between environments.

       Expect takes a rather liberal view of scoping.  In particular, variables 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  procedure you write that uses expect.  On the other hand, variables written 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 equivalent), 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 terminal  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  multiple  embedded \n's with non-whitespace characters between them.
       This seems sufficiently improbable, however the argument "-nobrace" 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.  Similarly, -brace forces a single argument to be handle as
       multiple patterns/actions.

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 timeouts 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 usually 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/bin

       Some implementations of ptys are designed so that the kernel throws away any unread output
       after  10  to 15 seconds (actual number is implementation-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  immediately  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
           }

       trap -code will not work with any command that sits in Tcl's event loop,  such  as  sleep.
       The  problem  is  that  in  the event loop, Tcl discards the return codes from async event
       handlers.  A workaround is to  set  a  flag  in  the  trap  code.   Then  check  the  flag
       immediately after the command (i.e., sleep).

       The expect_background command ignores -timeout arguments and has no concept of timeouts in
       general.

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
       environment   variable   EXPECT_PROMPT.    Code  like  the  following  can  be  used.   If
       EXPECT_PROMPT doesn't exist, the code still has a good chance of functioning 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 whatever  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 programs 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 characters 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 translated 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 forgiving 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, interactively 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 Programs" by Don Libes,
       pp. 602, ISBN 1-56592-090-2, O'Reilly and Associates, 1995.
       "expect: Curing Those Uncontrollable Fits of Interactivity" by Don Libes,  Proceedings  of
       the Summer 1990 USENIX Conference, Anaheim, California, June 11-15, 1990.
       "Using  expect  to  Automate System Administration Tasks" by Don Libes, Proceedings of the
       1990 USENIX  Large  Installation  Systems  Administration  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 Journals, 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 Sussex, 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 software.  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 portions of them are used.

                                         29 December 1994                               EXPECT(1)