#!/proj/tcl/install/5.x-sparc/bin/wish4.1

set f [open "bg.c" w]
puts $f {#include <stdio.h>
main(){printf("Hello\n");}}
close $f
set f [open "/tmp/junk.out" w+]
pack [frame .bb] -side top -fill x

#Note that the '-#' flag is how I turn on verbose compilation.
# adjust accordingly for your compiler.

button .bb.b -text "Compile it." -command {\
  after 1000 tail $f;\
  exec cc -# bg.c >>& /tmp/junk.out &\
}
pack .bb.b -side left
pack [label .bb.l -text "\\"] -side right
pack [scrollbar .sb -command ".t yview"] -side right -fill y
pack [text .t -yscrollc ".sb set"] -fill both -expand 1
set size 0
set state 0
proc tail {f} {
    global size
    file stat /tmp/junk.out stats
    if {$stats(size) != $size} {
	.t insert end [read $f [expr $stats(size)-$size]];.t yview 100
	set size $stats(size)
    }
    after 500 tail $f
}
    
proc rotate {} {
    global state
    .bb.l config -text [string index "\|/-" $state]
    set state [expr ($state>3?0:$state+1)]
    after 100 rotate
}

rotate