[cmdline] Match user expectations for &&, ||, goto, and exit

The && and || operators should be left-associative, since that is how
they are treated in most other languages (including C and Unix
shell).  For example, in the command:

  dhcp net0 && goto dhcp_ok || echo No DHCP on net0

if the "dhcp net0" fails then the "echo" should be executed.

After an "exit" or a successful "goto", further commands on the same
line should never be executed.  For example:

  goto somewhere && echo This should never be printed
  exit 0 && echo This should never be printed
  exit 1 && echo This should never be printed

An "exit" should cause the current shell or script to terminate and
return the specified exit status to its caller.  For example:

  chain test.ipxe && echo Success || echo Failure
    [in test.ipxe]
    #!ipxe
    exit 0

should echo "Success".

Signed-off-by: Michael Brown <mcb30@ipxe.org>

1 files changed, 0 insertions, 2 deletions

diff --git a/src/include/ipxe/command.h b/src/include/ipxe/command.h
index 2486e7aa2..a7d0ae462 100644
--- a/src/include/ipxe/command.h
+++ b/src/include/ipxe/command.h
@@ -23,6 +23,4 @@ struct command {
 
 #define __command __table_entry ( COMMANDS, 01 )
 
-extern int shell_exit;
-
 #endif /* _IPXE_COMMAND_H */