VtAddInput fileID cmd
Register a command or procedure callback that is called when an I/O stream is ready for file activity. When the stream referenced by fileID becomes readable, writable or generates an error, the callback command cmd is called with fileID as its argument. You can then read and write to the stream without fear of the interpreter blocking.
You must execute VtMainLoop to allow the callback to be called.
The following code fragment illustrates the use of VtAddInput to filter the output of a UNIX system command, in this case find.
proc dumpFoundCB {fid} {
set count 1
while { $count > 0 } {
set count [gets $fid line] ;# read a line of input
puts stdout ">> $line"
}
if { $count == -1 } { ;# end of file
echo "\n\nFinished"
exit 0
}
}
set cmd {| /bin/find /usr -name "*" -print}
# open the pipe
if [catch {set f [open $cmd ] } msg ] {
echo "open failed"
exit 1
}
#setup read handler on it..
VtAddInput $f dumpFoundCB
VtMainLoop