DouKaku?

| filename file numOfLines isFollowMode lineCount savedPosition |
filename := 'in.txt'.
numOfLines := 10.
isFollowMode := false.

file := FileStream fileNamed: filename.
file setToEnd.
file binary.
lineCount := 0.
[file position > 0 and: [lineCount < numOfLines]]
    whileTrue: [file back = 13 ifTrue: [lineCount := lineCount + 1]].

file ascii.
World findATranscript: nil.
Transcript cr; show: file upToEnd.
savedPosition := file position.
file close.
isFollowMode ifTrue: [
    [Sensor keyboardPressed] whileFalse: [
        (Delay forSeconds: 5) wait.
        file reopen; position: savedPosition.
        Transcript show: file upToEnd.
        savedPosition := file position.
        file close]]