Version 21 of How Expect sees function keys

Updated 2008-08-06 15:27:44 by Csan

Run this:

    puts "Type any characters, then <Return>."

    expect {
        ? {
            set result $expect_out(0,string)
            if {[string compare \n $result]} {
                scan $result %c value
                if {$value==27} {
                    puts "You just typed Esc (decimal ASCII 27)."
                } {
                    puts "You just typed '$result' (decimal ASCII $value)."
                }
            }
            exp_continue
        }
    }

Example output: type "a<CR>", see decimal 97; type "<F1><CR>", see the sequence

27-91-49-(49,50)-126 [explain] Win 95

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Also see "keysyms", CWIND, and "How to send escape characters through Expect".

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Csan The original code did not handle the Esc $result properly - it ate the second ' character in the output. I added a branch to handle that case.

I also extended the output to include the octal and hexadecimal values - useful for further re-use of the $result - see further on. Another addition was to save the resulting character (sequence) to keyseq.dat, which can be imported into another text editor. I find this addition very useful while using 'joe' editor...

2008-08-06: new version, with corrected output (cosmetic changes, prettier output, correct text), switched to string equal and also handling the Enter-only case

The new version of the script (I called it keyseqs.exp):

#!/usr/bin/expect

set timeout 10 set outfile ./keyseq.dat

set prompt "Type any characters followed by <Return>, wait for $timeout seconds or press Ctrl-C The resulting character sequence will be written to $outfile

Type here: "

set showheader 1 set seqsize 0 puts $prompt

expect {

  ? {
    set result $expect_out(0,string)
    if {![string equal \n $result]} {
      if {[catch {eof $fd}]} {
        set fd [open $outfile w]
      }
      scan $result %c dvalue

      set show $result
      if {$dvalue==27} {
          set show Esc
      }
      if {$showheader} {
        puts "\nWhat you have just entered I can see as the following byte sequence:\n"
        set showheader 0
      }
      puts "'$show'\t(ASCII octal [format %4s [format %#o $dvalue]], decimal [format %3s $dvalue], hexadecimal [format %x $dvalue])"

      puts -nonewline $fd $result
      incr seqsize
    } {
      if {$seqsize==0} {
        puts "You only typed Enter. $outfile is empty."
        set seqsize 0
      }
      if {![catch {eof $fd}]} {
        close $fd
        puts "\n$outfile created.\n-+----\n$prompt"
        set showheader 1
      }
    }
    exp_continue
  }

}

Example output (I typed PageUp):

 # ./keyseqs.exp
 Type any characters followed by <Return>, wait for 10 seconds or press Ctrl-C
 The resulting character sequence will be written to ./keyseq.dat

 Type here:

 ^[[5~

 What you have just entered I can see as the following byte sequence:

 'Esc'   (ASCII octal  033, decimal  27, hexadecimal 1b)
 '['     (ASCII octal 0133, decimal  91, hexadecimal 5b)
 '5'     (ASCII octal  065, decimal  53, hexadecimal 35)
 '~'     (ASCII octal 0176, decimal 126, hexadecimal 7e)

 ./keyseq.dat created.
 -+----
 Type any characters followed by <Return>, wait for 10 seconds or press Ctrl-C
 The resulting character sequence will be written to ./keyseq.dat

 Type here:

 #

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LV says: "Believe it or not, there is no set standard for what function keys generate. In fact, depending on the application, the same function key could generate different values [for different applications] on some systems."

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[ Category Expect | Category Characters ]