shell
You may enter any command while in the sub-shell.
The PGM_$INVOKE system call is used to invoke /com/sh with
your command as argument.
To return to Garfield, type:
return
There are no constraints on the use of the $ to give DCL commands,
except that one additional subprocess is needed - which may cause
trouble if the subprocess quotum is low on your Vax.
The LIB$SPAWN system call is used.
To return from the subprocess to Garfield, type:
LOGOUT
Issuing VM/CMS commands from within the program is a delicate
exercise: no other program may be executed\ ... which is something
lots of commonly used public EXEC files do. No protection against
the consequences of wrong use is offered. You will normally notice
that something went wrong in the form of a delayed program crash.
(The program should never crash under normal operation.)
Trips to the outside world are safe since they employ SUBSET mode,
in which no illegal commands - in the above sense - are permitted.
This mode of use is therefore recommended.
The CERN library routine VMCMS is used, see its documentation for
details about the restrictions.
To get back into Garfield, type:
RETURN
Unix comes with a variety of shells. By default, your commands
will be executed via the shell contained in the environment
variable "SHELL" (or "shell" if "SHELL" is not set). If not set,
the "trusted C shell", tcsh is assumed. If you prefer another
shell, then insert a line like:
SHELL "csh"
in your
initialisation file.
Note the double quotes around the shell name.
As for most parameter setting commands, one can type SHELL without
arguments to find out what the current setting is.
The shell is called via a C language interface to the "system"
procedure, and there are no restriction on the commands you can
issue from sub-shell.
To return to Garfield, type:
exit
Go to the top level,
to shell,
to the topic index,
to the table of contents, or to the full text.
Formatted on 21/01/18 at 16:55.