set file [open D:/rob/tcl/uptime.log a]
set uptime [exec D:/rob/tcl/uptime.exe]

namespace eval up {
    proc closefile {} {
        variable file
        variable uptime
        puts "closing $file"
        close $file
    }

    proc uptime {} {
        variable uptime
        variable file
        puts $file $uptime
        puts "$uptime is written to $file."
        closefile $file
    }
}