.TH EXPECT 1 "29 December 1994"

.SH NAME

expect \- programmed dialogue with interactive programs, Version 5

.SH SYNOPSIS

.B expect

[

.B \-dDinN

]

[

.B \-c

.I cmds

]

[

[

.BR \- [ f | b ]

]

.I cmdfile

]

[

.I args

]

.SH INTRODUCTION

.B Expect

is a program that "talks" to other interactive programs according to a

script.  Following the script,

.B 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.

.PP

.B Expectk

is a mixture of

.B Expect

and

.BR Tk .

It behaves just like

.B Expect

and

.BR Tk 's

.BR wish .

.B Expect

can also be used directly in C or C++ (that is, without Tcl).

See libexpect(3).

.PP

The name "Expect" comes from the idea of

.I send/expect

sequences popularized

by uucp, kermit and other modem control programs.

However unlike uucp,

.B Expect

is generalized so that it can be run as a user-level command

with any program and task in mind.

.B Expect

can actually talk to several programs at the same time.

.PP

For example, here are some things

.B Expect

can do:

.RS

.TP 4

\(bu

Cause your computer to dial you back,

so that you can login without paying for the call.

.TP

\(bu

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.

.TP

\(bu

Run fsck, and in response to its questions, answer "yes", "no" or give control back to you,

based on predetermined criteria.

.TP

\(bu

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.

.TP

\(bu

Carry environment variables, current directory,

or any kind of information across rlogin, telnet, tip, su, chgrp, etc.

.RE

.PP

There are a variety of reasons why the shell cannot perform these tasks.

(Try, you'll see.)

All are possible with

.BR Expect .

.PP

In general,

.B 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.

.B 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.

.SH USAGE

.B Expect

reads

.I cmdfile

for a list of commands to execute.

.B 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

.B Expect

lives.  /usr/local/bin is just an example.

The

.B \-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

.B \-c

by separating them with semicolons.

Commands are executed in the order they appear.  

(When using Expectk, this option is specified as

.BR \-command .)

.PP

The

.B \-d

flag enables some diagnostic output, which

primarily reports internal activity of commands such as 

.B expect

and

.BR interact .

This flag has the same effect as "exp_internal 1" at the beginning of an Expect

script, plus the version of

.B Expect

is printed.

(The

.B strace

command is useful for tracing statements, and the

.B trace

command is useful for tracing variable assignments.)

(When using Expectk, this option is specified as

.BR \-diag .)

.PP

The

.B \-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

.BR \-Debug .)

.PP

The

.B \-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

.BR \-file .)

.PP

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 \-b

flag.

(When using Expectk, this option is specified as

.BR \-buffer .)

Note that stdio-buffering may still take place however this shouldn't cause

problems when reading from a fifo or stdin.

.PP

If the string "\-" is supplied as a filename, standard input is read instead.

(Use "./\-" to read from a file actually named "\-".)

.PP

The

.B \-i

flag causes

.B Expect

to interactively prompt for commands instead of reading

them from a file.

Prompting is terminated via the

.B exit

command or upon EOF.

See

.B interpreter

(below) for more information.

.B \-i

is assumed if neither a command file nor

.B \-c

is used.

(When using Expectk, this option is specified as

.BR \-interactive .)

.PP

.B \-\-

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

.BR 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

.IR argv .

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

Note that the usual getopt(3) and execve(2) conventions must be observed

when adding arguments to the #! line.

.PP

The file $exp_library/expect.rc is sourced automatically if present, unless

the

.B \-N

flag is used.  

(When using Expectk, this option is specified as

.BR \-NORC .)

Immediately after this,

the file ~/.expect.rc is sourced automatically, unless the

.B \-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

.BR \-norc .)

This sourcing occurs only after executing any

.B \-c

flags.

.PP

.B \-v

causes Expect to print its version number and exit.  (The corresponding flag

in Expectk, which uses long flag names, is \-version.)

.PP

Optional

.I args

are constructed into a list and stored in the variable named

.IR argv .

.I argc

is initialized to the length of argv.

.PP

.I 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:

.nf

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

.fi

.SH COMMANDS

.B Expect

uses

.I 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.,

.BR set ,

.BR if ,

.BR exec )

are Tcl commands (see tcl(3)).

.B Expect

supports additional commands, described below.

Unless otherwise specified, commands return the empty string.

.PP

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

.BR spawn ,

.BR send ,

.BR expect ,

and

.BR 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

.B Expect

program while "expect" with a lower-case "e" refers to the

.B expect

command within the

.B Expect

program.)

.I

.TP 6

.BI 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

.B close

usually suffices to kill the process as well.

The

.B \-i

flag declares the process to close corresponding to the named spawn_id.

Both

.B expect

and

.B interact

will detect when the current process exits and implicitly do a

.BR close .

But if you kill the process by, say, "exec kill $pid",

you will need to explicitly call

.BR close .

The

.BR \-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 

.B \-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

.B wait

to clear up the corresponding kernel process slot.

.B close

does not call

.B wait

since there is no guarantee that closing a process connection will cause

it to exit.

See

.B wait

below for more info.

.TP

.BI 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

.B \-now

flag, the debugger is started immediately (i.e., in the middle of the

.B debug

command itself).  Otherwise, the debugger is started with the next

Tcl statement.

The

.B debug

command does not change any traps.  Compare this to starting Expect with the 

.B -D

flag (see above).

See the README file or SEE ALSO (below)

for more information on the debugger.

.TP

.B 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.

.IP

The following fragment uses

.B disconnect

to continue running the script in the background.  

.nf

    if {[fork]!=0} exit

    disconnect

    . . .

.fi

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

.B stty

command which demonstrates how to turn off password echoing.)

.nf

    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

    }

.fi

An advantage to using

.B disconnect

over the shell asynchronous process feature (&) is that

.B Expect

can

save the terminal parameters prior to disconnection, and then later

apply them to new ptys.  With &,

.B Expect

does not have a chance

to read the terminal's parameters since the terminal is already

disconnected by the time

.B Expect

receives control.

.TP

.BI exit " [\-opts] [status]"

causes

.B Expect

to exit or otherwise prepare to do so.

The

.B \-onexit

flag causes the next argument to be used as an exit handler.

Without an argument, the current exit handler is returned.

The

.B \-noexit

flag causes

.B 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

.B 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.

.B 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.

.I status

(or 0 if not specified) is returned as the exit status of

.BR Expect .

.B exit

is implicitly executed if the end of the script is reached.

.TP

\fBexp_continue\fR [-continue_timer]

The command

.B exp_continue

allows

.B expect

itself to continue

executing rather than returning as it normally would. By

default

.B exp_continue

resets the timeout timer. The

.I -continue_timer

flag prevents timer from being restarted. (See

.B expect

for more information.)

.TP

.BI exp_internal " [\-f file] value"

causes further commands to send diagnostic information internal to

.B Expect

to stderr if

.I value

is non-zero.  This output is disabled if

.I value

is 0.  The diagnostic information includes every character received,

and every attempt made to match the current output against the patterns.

.IP

If the optional

.I file

is supplied, all normal and debugging output is written to that file

(regardless of the value of

.IR value ).

Any previous diagnostic output file is closed.

The

.B \-info

flag causes exp_internal to return a description of the

most recent non-info arguments given.

.TP

.BI 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

.B open

command.  (The spawn id should no longer be used.  A

.B wait

should not be executed.

The

.B \-leaveopen

flag leaves the spawn id open for access through 

Expect commands.  A

.B wait

must be executed on the spawn id.

.TP

.BI exp_pid " [\-i spawn_id]"

returns the process id corresponding to the currently spawned process.

If the

.B \-i

flag is used, the pid returned corresponds to that of the given spawn id.

.TP

.B exp_send

is an alias for

.BR send .

.TP

.B exp_send_error

is an alias for

.BR send_error .

.TP

.B exp_send_log

is an alias for

.BR send_log .

.TP

.B exp_send_tty

is an alias for

.BR send_tty .

.TP

.B exp_send_user

is an alias for

.BR send_user .

.TP

.BI exp_version " [[\-exit] version]"

is useful for assuring that the script is compatible with the current

version of Expect.

.IP

With no arguments, the current version of

.B 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.

.IP

Versions consist of three numbers separated by dots.  First

is the major number.  Scripts written for versions of

.B Expect

with a

different major number will almost certainly not work.

.B exp_version 

returns an error if the major numbers do not match.

.IP

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.

.B exp_version

returns an error if the major numbers match, but the script minor number

is greater than that of the running

.BR Expect .

.IP

Third is a number that plays no part in the version comparison.

However, it is incremented when the

.B 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.

.IP

With the

.B \-exit

flag,

.B Expect

prints an error and exits if the version is out of date.

.TP

.BI 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.

.IP

Patterns from the most recent

.B expect_before

command are implicitly used before any other patterns.

Patterns from the most recent

.B expect_after

command are implicitly used after any other patterns.

.IP

If the arguments to the entire

.B 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.

.IP

If a pattern is the keyword

.BR eof ,

the corresponding body is executed upon end-of-file.

If a pattern is the keyword

.BR 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

.BR default ,

the corresponding body is executed upon either timeout or end-of-file.

.IP

If a pattern matches, then the corresponding body is executed.

.B 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.

.IP

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

.B timeout

(just like you would if you were interacting manually).

.IP

Patterns are specified in three ways.  By default, 

patterns are specified as with Tcl's

.B string match

command.  (Such patterns are also similar to C-shell regular expressions

usually referred to as "glob" patterns).  The

.B \-gl

flag may may

be used to protect patterns that might otherwise match

.B expect

flags from doing so.

Any pattern beginning with a "-" should be protected this way.  (All strings

starting with "-" are reserved for future options.)

.IP

For example, the following fragment looks for a successful login.

(Note that

.B abort

is presumed to be a procedure defined elsewhere in the script.)

.nf

.ta \w'      expect 'u +\w'invalid password    'u

    expect {

        busy               {puts busy\\n ; exp_continue}

        failed             abort

        "invalid password" abort

        timeout            abort

        connected

    }

.fi

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.

.IP

Regexp-style patterns follow the syntax defined by Tcl's

.B regexp

(short for "regular expression") command.

regexp patterns are introduced with the flag

.BR \-re .

The previous example can be rewritten using a regexp as:

.nf

.ta \w'      expect 'u +\w'connected    'u

    expect {

        busy       {puts busy\\n ; exp_continue}

        \-re "failed|invalid password" abort

        timeout    abort

        connected

    }

.fi

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

.B \-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.

.IP

The

.B \-nocase

flag causes uppercase characters of the output to compare as if they were

lowercase characters.  The pattern is not affected.

.IP

While reading output,

more than 2000 bytes can force earlier bytes to be "forgotten".

This may be changed with the function

.BR match_max .

(Note that excessively large values can slow down the pattern matcher.)

If

.I patlist

is

.BR full_buffer ,

the corresponding body is executed if

.I match_max

bytes have been received and no other patterns have matched.

Whether or not the

.B full_buffer

keyword is used, the forgotten characters are written to

expect_out(buffer).

If

.I patlist

is the keyword

.BR null ,

and nulls are allowed (via the

.B 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

.IR expect_out(buffer) .

Up to 9 regexp substring matches are saved in the variables

.I expect_out(1,string)

through

.IR expect_out(9,string) .

If the

.B -indices

flag is used before a pattern,

the starting and ending indices (in a form suitable for

.BR lrange )

of the

10 strings are stored in the variables

.I expect_out(X,start)

and

.I 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:

.nf

    expect "cd"

.fi

is as if the following statements had executed:

.nf

    set expect_out(0,string) cd

    set expect_out(buffer) abcd

.fi

and "efgh\\n" is left in the output buffer.

If a process produced the output "abbbcabkkkka\\n", the result of:

.nf

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

.fi

is as if the following statements had executed:

.nf

    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

.fi

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.

.IP

Normally, the matched output is discarded from Expect's internal buffers.

This may be prevented by prefixing a pattern with the

.B \-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

.IR expect_out(spawn_id) .

The

.B \-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

.B \-i

flag declares the output from the named spawn_id list be matched against

any following patterns (up to the next

.BR \-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.

.nf

    expect {

        \-i $proc2 busy {puts busy\\n ; exp_continue}

        \-re "failed|invalid password" abort

        timeout abort

        connected

    }

.fi

The value of the global variable

.I any_spawn_id

may be used to match patterns to any spawn_ids that are named

with all other

.B \-i

flags in the current

.B expect

command.

The spawn_id from a

.B \-i

flag with no associated pattern (i.e., followed immediately

by another

.BR \-i )

is made available to any other patterns

in the same

.B expect

command associated with

.I any_spawn_id.

The

.B \-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

.B break

and

.B continue

cause control structures (i.e.,

.BR for ,

.BR proc )

to behave in the usual way.

The command

.B exp_continue

allows

.B expect

itself to continue

executing rather than returning as it normally would.

.IP

This is useful for avoiding explicit loops or repeated expect statements.

The following example is part of a fragment to automate rlogin.  The

.B exp_continue

avoids having to write a second

.B expect

statement (to look for the prompt again) if the rlogin prompts for a password.

.nf

    expect {

        Password: {

            stty -echo

            send_user "password (for $user) on $host: "

            expect_user -re "(.*)\\n"

            send_user "\\n"