File: sed.info,  Node: Exit status,  Prev: Command-Line Options,  Up: Invoking sed

2.3 Exit status
===============

An exit status of zero indicates success, and a nonzero value indicates
failure.  GNU ‘sed’ returns the following exit status error values:

0
     Successful completion.

1
     Invalid command, invalid syntax, invalid regular expression or a
     GNU ‘sed’ extension command used with ‘--posix’.

2
     One or more of the input file specified on the command line could
     not be opened (e.g.  if a file is not found, or read permission is
     denied).  Processing continued with other files.

4
     An I/O error, or a serious processing error during runtime, GNU
     ‘sed’ aborted immediately.

   Additionally, the commands ‘q’ and ‘Q’ can be used to terminate ‘sed’
with a custom exit code value (this is a GNU ‘sed’ extension):

     $ echo | sed 'Q42' ; echo $?
     42