example exec from script

set dir [lindex $argv 0]
if {[catch {glob -directory $dir *} files]} {
  exit 1
} else {
  set i [expr {int(rand() * [llength $files])}]
  set o [lindex $files $i]
  if {[catch {exec cat $o} r]} {
    puts stderr "[lindex $argv 0]: $r"
    exit 2
  }
}