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 ontrol-A\n”;
      send “\001”
  }
  $ {
      send_user “The date is \
        [exec date].”}
  \003 exit
   foo {
     send_user “bar”
  }
  ~~
}

In string-body pairs, strings are matched in the order they are listed as arguments.  Strings that partially match are not sent to the current process in anticipation of the remainder coming.  If characters are then entered such that there can no longer 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 wildcards.  (In contrast, the expect command uses glob-style patterns by default.) 

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. 

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.