(List
  (Com {[LIT_CHARS echo]} {[SQ <LIT_CHARS "--- setlock requires arguments">]}  )
  (Com {[LIT_CHARS setlock]} {[LIT_CHARS whatever]}  )
  (Com {[LIT_CHARS echo]} {[VarSub ?]}  )
  (Com {[LIT_CHARS echo]} {[SQ <LIT_CHARS "--- setlock complains if it cannot create lock file">]}  )
  (Com {[LIT_CHARS setlock]} {[LIT_CHARS nonexistent/lock]} {[LIT_CHARS echo]} {[LIT_CHARS wrong]}  )
  (Com {[LIT_CHARS echo]} {[VarSub ?]}  )
  (Com {[LIT_CHARS echo]} {[SQ <LIT_CHARS "--- setlock -x exits quietly if it cannot create lock file">]}  )
  (Com {[LIT_CHARS setlock]} {[LIT_CHARS -x]} {[LIT_CHARS nonexistent/lock]} {[LIT_CHARS echo]} {[LIT_CHARS wrong]}  )
  (Com {[LIT_CHARS echo]} {[VarSub ?]}  )
  (Com {[LIT_CHARS echo]} {[SQ <LIT_CHARS "--- setlock creates lock file">]}  )
  (Com {[LIT_CHARS setlock]} {[LIT_CHARS lock]} {[LIT_CHARS echo]} {[LIT_CHARS ok]}  )
  (Com {[LIT_CHARS echo]} {[VarSub ?]}  )
  (Com {[LIT_CHARS echo]} {[SQ <LIT_CHARS "--- setlock does not truncate lock file">]}  )
  (Com {[LIT_CHARS echo]} {[LIT_CHARS ok]}
    <
    (FilenameRedirectNode filename={[LIT_CHARS lock]} <REDIR_GREAT ">"> 1),
    >
  )
  (Com {[LIT_CHARS setlock]} {[LIT_CHARS lock]} {[LIT_CHARS cat]} {[LIT_CHARS lock]}  )
  (Com {[LIT_CHARS echo]} {[VarSub ?]}  )
  (Com {[LIT_CHARS rm]} {[LIT_CHARS -f]} {[LIT_CHARS lock]}  )
  (Com {[LIT_CHARS echo]} {[SQ <LIT_CHARS "--- setlock -n complains if file is already locked">]}  )
  (Com {[LIT_CHARS setlock]} {[LIT_CHARS lock]} {[LIT_CHARS sh]} {[LIT_CHARS -c]} {[SQ <LIT_CHARS "setlock -n lock echo one && echo two">]}  )
  (Com {[LIT_CHARS echo]} {[VarSub ?]}  )
  (Com {[LIT_CHARS echo]} {[SQ <LIT_CHARS "--- setlock -nx exits quietly if file is already locked">]}  )
  (Com {[LIT_CHARS setlock]} {[LIT_CHARS lock]} {[LIT_CHARS sh]} {[LIT_CHARS -c]} {[SQ <LIT_CHARS "setlock -nx lock echo one && echo two">]}  )
  (Com {[LIT_CHARS echo]} {[VarSub ?]}  )
)