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AUTOEXPECT(1)            USER COMMANDS               30 June 1995


autoexpect - generate an Expect script from watching a  ses-


autoexpect [ args ] [ program args... ]


autoexpect watches you interacting with another program  and
     creates  an Expect script that reproduces your interactions.
     For straightline scripts, autoexpect saves substantial  time
     over  writing  scripts  by  hand.  Even if you are an Expect
     expert, you will find it convenient  to  use  autoexpect  to
     automate  the  more  mindless  parts of interactions.  It is
     much  easier  to  cut/paste  hunks  of  autoexpect   scripts
     together  than to write them from scratch.  And if you are a
     beginner, you may be able to get away with learning  nothing
     more about Expect than how to call autoexpect.

     The simplest way to use autoexpect is to call  it  from  the
     command line with no arguments.  For example:

          % autoexpect

     By default, autoexpect spawns a shell for you.  Given a pro-
     gram  name  and  arguments,  autoexpect spawns that program.
     For example:

          % autoexpect ftp ftp.cme.nist.gov

     Once your spawned program  is  running,  interact  normally.
     When  you  have exited the shell (or program that you speci-
     fied), autoexpect will create a  new  script  for  you.   By
     default,  autoexpect  writes the new script to "script.exp".
     You can override this with the -f flag  followed  by  a  new
     script name.

     The following example runs "ftp ftp.cme.nist.gov" and stores
     the resulting Expect script in the file "nist".

          % autoexpect -f nist ftp ftp.cme.nist.gov

     It is important  to  understand  that  autoexpect  does  not
     guarantee  a  working  script  because it necessarily has to
     guess about certain things -  and  occasionally  it  guesses
     wrong.  However, it is usually very easy to identify and fix
     these problems.  The typical problems are:

          +   Timing.  A surprisingly large  number  of  programs
              (rn,  ksh,  zsh,  telnet,  etc.) and devices (e.g.,
              modems) ignore keystrokes that arrive "too quickly"
              after prompts.  If you find your new script hanging

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AUTOEXPECT(1)            USER COMMANDS               30 June 1995

              up at one spot,  try  adding  a  short  sleep  just
              before the previous send.

              You can force this behavior throughout by  overrid-
              ing  the  variable  "force_conservative"  near  the
              beginning of the generated script.  This "conserva-
              tive"  mode  makes  autoexpect  automatically pause
              briefly (one tenth of a second) before sending each
              character.  This pacifies every program I know of.

              This conservative mode is useful if you  just  want
              to  quickly reassure yourself that the problem is a
              timing one (or if you really don't care  about  how
              fast  the  script  runs).   This  same  mode can be
              forced before script generation  by  using  the  -c

              Fortunately, these  timing  spots  are  rare.   For
              example,   telnet  ignores  characters  only  after
              entering its escape sequence.  Modems  only  ignore
              characters immediately after connecting to them for
              the  first  time.   A  few  programs  exhibit  this
              behavior  all  the time but typically have a switch
              to disable it.  For example, rn's -T flag  disables
              this behavior.

              The following example starts autoexpect in  conser-
              vative mode.

                   autoexpect -c

              The -C flag defines a key  to  toggle  conservative
              mode.  The  following example starts autoexpect (in
              non-conservative  mode)  with  ^L  as  the  toggle.
              (Note  that  the  ^L  is  entered literally - i.e.,
              enter a real control-L).

                   autoexpect -C ^L

              The following example starts autoexpect in  conser-
              vative mode with ^L as the toggle.

                   autoexpect -c -C ^L

          +   Echoing.  Many program echo characters.  For  exam-
              ple, if you type "more" to a shell, what autoexpect
              actually sees is:

                   you typed 'm',
                   computer typed 'm',
                   you typed 'o',

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AUTOEXPECT(1)            USER COMMANDS               30 June 1995

                   computer typed 'o',
                   you typed 'r',
                   computer typed 'r',

              Without specific knowledge of the  program,  it  is
              impossible  to  know if you are waiting to see each
              character  echoed  before  typing  the  next.    If
              autoexpect sees characters being echoed, it assumes
              that it can send them all as a  group  rather  than
              interleaving them the way they originally appeared.
              This makes the script more pleasant to read.   How-
              ever,  it  could  conceivably  be  incorrect if you
              really had to wait to see each character echoed.

          +   Change.  Autoexpect records  every  character  from
              the  interaction  in the script.  This is desirable
              because it gives you the ability to make judgements
              about  what  is  important and what can be replaced
              with a pattern match.

              On the other hand, if you use commands whose output
              differs  from run to run, the generated scripts are
              not going to be correct.  For example,  the  "date"
              command always produces different output.  So using
              the date command while running autoexpect is a sure
              way  to  produce a script that will require editing
              in order for it to work.

              The -p flag puts autoexpect into "prompt mode".  In
              this  mode,  autoexpect  will only look for the the
              last line of program output - which is usually  the
              prompt.   This handles the date problem (see above)
              and most others.

              The following example starts autoexpect  in  prompt

                   autoexpect -p

              The -P flag defines a key to  toggle  prompt  mode.
              The  following  example  starts autoexpect (in non-
              prompt mode) with ^P as the toggle.  Note that  the
              ^P  is  entered  literally  -  i.e.,  enter  a real

                   autoexpect -P ^P

              The following example starts autoexpect  in  prompt
              mode with ^P as the toggle.

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AUTOEXPECT(1)            USER COMMANDS               30 June 1995

                   autoexpect -p -P ^P


The -quiet flag disables informational messages produced  by

     The -Q flag names a quote character which  can  be  used  to
     enter  characters  that  autoexpect  would otherwise consume
     because they are used as toggles.

     The following example shows a number  of  flags  with  quote
     used to provide a way of entering the toggles literally.

          autoexpect -P ^P -C ^L -Q ^Q


I don't know if there is a "style" for Expect  programs  but
     autoexpect  should definitely not be held up as any model of
     style.  For example, autoexpect uses features of Expect that
     are  intended specifically for computer-generated scripting.
     So don't try to faithfully write scripts that appear  as  if
     they were generated by autoexpect.  This is not useful.

     On  the  other  hand,  autoexpect  scripts  do   show   some
     worthwhile  things.  For example, you can see how any string
     must be quoted in order to use it in a Tcl script simply  by
     running the strings through autoexpect.


"Exploring  Expect:  A  Tcl-Based  Toolkit  for   Automating
     Interactive Programs" by Don Libes, O'Reilly and Associates,
     January 1995.


Don Libes, National Institute of Standards and Technology

     expect and autoexpect are in the public domain.  NIST and  I
     would  appreciate  credit if these programs or parts of them
     are used.

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