Advanced script programming

• PowerTerm Script language uses many `{` and not many `(`
• NO: if ( $variable == "hello" )
  YES: if { $variable == "hello" }
• Variable assignment does not use a `$`. Variable reference does.
• NO: $var = $data
  YES: var = $data
• assignment `=` must be surrounded by whitespace.
  (tests need not be surrounded by whitespace -- `if {$var<=10}` is acceptable.)

  NO: i=1
  YES: i = 1

• The `{` starting a block of statements MUST be on the same line as the `if`, `for` ... statement.
• YES: if { $data == 10 } {
  i = 45
  }

  NO: if { $data == 10 }
  {
  i = 45
  }

• incrementing is interesting...
• use the `expr` command which evaluates an expression, and the `[ ...]` facility which replaces itself with the result.

  Thus, i = [ expr $i + 1 ]
  or, use the `incr` command which increments its argument (and because there is an assignment involved, no `$` is used.
  i = [ incr i ]
  .. or ..
  i = [incr i 3 ] # increment by 3

• `for` loop syntax is tricky:
• as usual, there are 4 parts
  • initialization
  • test
  • increment
  • body statements
  ALL 4 PARTS ARE individually wrapped in `{...}`
  AND -- as indicated above -- the `{` beginning the body statements MUST be on the same line as the 3 earlier parts:

  NO: for (i=0; $i <10; $i++)
  var = 45
  

  YES: for {i = 0} {$i <10} { i="[incr" i]} {
  var = 45
  }

• Testing for Time Outs in `wait` Here is an illustration of a script which uses a wait statement and an if to test the result:
• str = [wait 10 for "hi there"]
  if {$str == "1"} {message "Hello to you"} else {message "no one home, $str"}

  For an unconditional wait, the `wait` command can be used in this manner:

  wait 10 seconds # [always say `seconds`, even in `wait 1 seconds`]

• `wait`-ing for a string in a designated location The wait command can look for a string in a designated location, as in:
• wait 10 for "F1" at 23 70

  This will wait 10 seconds for the string "F1" to appear in row 23, column 70.

• Message and input boxes

  PowerTerm lets the script writer create pop-up boxes for 3 purposes: messages, text input and password-type input.

  • Message box.
    syntax: message text [title-text] [error|question|info]

    This will popup a box whose optional title is title-text, with the content of text, and with an optional icon suitable for error, question, or info. The user presses the OK button to continue.

  • Text input box.
    syntax: input-line text [title-text]

    This will popup a box which includes a text input area. The box has text of text, and an optional title of title-text. You can assign the input to a variable as in:

    data = [input-line "Enter Name" "My Title"]

  • password-type input box.
    syntax: input-password text [title-text]

    This command is similar to input-line, except that the text which the user inputs is not echoed back to the screen. Rather, `*` symbols are displayed.

• Sending Hex Characters. This is done via `/xnnn`. example:
  key f3 do {send "\x301"}
• Sending the Null `0` Character. This is done with the special character <null>. example: you need to send `ABCZDEF` where `Z` means the NULL `0` character. key f7 do {send "ABC<null>DEF"}
• Sending the `Enter` key: for Unix/VMS, `^M` represents the Enter/Return key. For IBM Mainframe/Midrange, <enter> is the way to do it.
• To include a filename in a script, it is necessary to use 2 backslash characters to represent each backslash. example: to refer to the file \tmp\myfile.txt , say \\tmp\\myfile.txt
• To access a PC environment variable within a script, use the `GETENV` command. Here is an example:
• data = [getenv TMP]
  if {$data == "bernie"} {message "yes"} else {message "no"}
• To learn the current cursor position:
• get col is the command for the column
  get row is the command for the row
• To make a script `pause` after it executes a PC program:
• The problem is that lines like:
  ...
  ...
  result = [exec MYPROG.EXE]
  if {$result == 0} {return}
  message "The Program failed" ERROR
  ...
  ...

  Will not behave as expected because the script will execute the `if {$result == 0} {return}` line immediately after starting MYPROG.EXE

  The solution is to have the script create a temp file, and to modify MYPROG.EXE to delete this file as its last operation.

  Then the script can be re-written as follows:

  ....
  ...
  open "\\temp\\temp.dat" w
  result = [exec MYPROG.EXE] #This will erase \temp\fred.dat when it completes
  while { 1 == 1 }

  wait 1 seconds
  isfile = [file exists "\\temp\\temp.dat"]
  if {$isfile == 0} {break}
  }

  if {$result == 0} {return} ##the files does NOT exist
  message "The Program failed" ERROR
  ...
  ...
• To use the proc script command:
• The proc must be defined before it is used [remember, the script language is an interpreter.] Here is an example of usage of proc.

  proc say_hello x
  message $x
  }

  say_hello Josephine

• To exit PowerTerm under control of a script:
• exit-emulator is the command