Korn Shell: Unix and Linux Programming Manual, Third Edition, The

EXIT STATUS

Errors detected by the shell, such as syntax errors, cause the shell to return a non-zero exit status. Otherwise, the shell returns the exit status of the last command executed (see also the exit command above). If the shell is being used non-interactively, then execution of the shell file is abandoned. Run time errors detected by the shell are reported by printing the command or function name and the error condition. If the line number that the error occurred on is greater than one, then the line number is also printed in square brackets ([]) after the command or function name.