diff --git a/doc/src/sgml/backup.sgml b/doc/src/sgml/backup.sgml
index bdffb4b859e..b8daedcbb6e 100644
--- a/doc/src/sgml/backup.sgml
+++ b/doc/src/sgml/backup.sgml
@@ -579,7 +579,7 @@ tar -cf backup.tar /usr/local/pgsql/data
     character in the command.  The simplest useful command is something
     like:
 
-archive_command = 'test ! -f /mnt/server/archivedir/%f && cp %p /mnt/server/archivedir/%f'  # Unix
+archive_command = 'test ! -f /mnt/server/archivedir/%f && cp %p /mnt/server/archivedir/%f'  # Unix
 archive_command = 'copy "%p" "C:\\server\\archivedir\\%f"'  # Windows
 
     which will copy archivable WAL segments to the directory
@@ -1213,7 +1213,7 @@ restore_command = 'cp /mnt/server/archivedir/%f %p'
       on>, and set up an archive_command> that performs
       archiving only when a switch file> exists.  For example:
 
-archive_command = 'test ! -f /var/lib/pgsql/backup_in_progress || cp -i %p /var/lib/pgsql/archive/%f < /dev/null'
+archive_command = 'test ! -f /var/lib/pgsql/backup_in_progress || (test ! -f /var/lib/pgsql/archive/%f && cp %p /var/lib/pgsql/archive/%f)'
 
       This command will perform archiving when
       /var/lib/pgsql/backup_in_progress> exists, and otherwise