(command.CommandList children: [ (C {<echo>} {(SQ <'--- pgrphack insists on an argument'>)}) (command.CommandList children: [ (command.Sentence child:(C {<pgrphack>}) terminator:<Id.Op_Semi _>) (C {<echo>} {($ Id.VSub_QMark '$?')}) ] ) (C {<echo>} {(SQ <'--- pgrphack complains if it cannot run program'>)}) (command.CommandList children: [ (command.Sentence child: (C {<pgrphack>} {<'./nonexistent'>}) terminator: <Id.Op_Semi _> ) (C {<echo>} {($ Id.VSub_QMark '$?')}) ] ) (C {<echo>} {(SQ <'--- pgrphack runs a program'>)}) (command.CommandList children: [ (command.Sentence child:(C {<pgrphack>} {<echo>} {<ok>}) terminator:<Id.Op_Semi _>) (C {<echo>} {($ Id.VSub_QMark '$?')}) ] ) ] )