B.2 System keywords

The 'hidden' system keywords, although overridden by any program defined counterpart, can also be set by an equivalent environment variable (in upper case), and are:

help=

Sets the help level to a program. As with all system keywords, their value can be fixed for a session by setting the appropriate environment variable in upper case, e.g. "setenv HELP 5". By using the keyword form, the value of the environment variable will be ignored.

The individual help levels are numeric and add up to combine functionality, and are hence powers of 2:

1

Remembers previous usage of a program, by maintaining a keyword file from program to program. These files are normally stored in the current directory, but can optionally be stored in one common directory if the environment variable NEMODEF^B.1 is set. The keyword files have the name "progname".def, e.g. snapshot.def^B.2. When using this lowest help-level it is still possible to use UNIX I/O redirection. This help level reads, as well as writes the keyword file during the program execution; hence the user needs both read and write permission in the keyword directory. As can also be seen, programs cannot run in parallel while using this help-level: they might compete for the same keyword file. Within the simple commandline interface it is not possible to maintain a global keyword database, as is e.g. the case in AIPS; you would have to use the miriad shell.

2

prompts the user for a (new) value for every keyword; it shows the default (old) value on the prompt line, which can then be edited. It is not possible to combine this level with UNIX I/O redirection. By combining the previous helplevel with this one, previous values and modified ones are maintained in a keyword file.

4

provides a simple fullscreen menu interface, by having the user edit the keyword file. The environment variable EDITOR can be used to set any other editor than good old vi(1). It is not possible to combine this level with UNIX I/O redirection.

8,16,...

although not processed, it is reserved for the next levels of menu interface.

Example: ``help=3'' will remember old keywords in a local keyword file, prompt you with new values, and puts the new values in the keyword file for the next time. The ``help=5'' option happen to be somewhat similar to the way AIPS and IRAF appear to the user.

Help levels can also include an alpha-string, which generally display the values of the keyword, their default values or their help strings.

?

lists all these options, as a reminder. It also displays the version of the getparam user interface package.

h

list all the keywords, plus a help string what the keywords does/expects. This is really what we call the inline manual or inline help.

a

list all arguments in the form keyword=value.

p,k

list parameters (keywords) of all arguments in the form keyword.

d,v

list defaults (values) of all arguments in the form value.

n

add a newline to every keyword/value string on output. In this way a keyword file could be build manually by redirecting this output.

t

output a documentation file according to the %N,%A specifications of miriad^B.3. Is mainly intended to be used by scripts such as mktool. The procedure in NEMO to update a .doc file would be:

         % program help=t > $NEMODOC/program.doc
    or:
         % mktool program 

if the script mktool has been installed^B.4

q

quit, do not start program. Useful when the helpstring contains options to print.

Example: key=val help=1q redefines a keyword in the keywordfile, but does not run the program. This is also a way to 'repair' a keyword file, when the program has been updated with new keywords. key=val help=1aq redefines the keyword, shows the results but does still not run the program. Finally, key=val help=1a redefines a keyword, shows the result and then runs the program.

host=

Runs the program on a remote host. It depends on the implementation of software on local as well as remote host if and how this option works. Among SUN systems the rsh command is used, and assumes a shared disk with the same absolute pathname (NFS). Future implementations will have to use more sophisticated RPC (Remote Procedure Call) or X11 interfaces for distributed networking. No environment variable is used here.

debug=

Changes the debug output level. The higher the debug level, the more output can appear on the standard error output device stderr. The default value is either 0 or the value set by the DEBUG environment variable. The use of the debug= keyword will override your default setting. A value of '0' for debug may still show some warning messages. Setting debug to -1 will prevent even those warning/debug messages. Legal values are 0 through 9. Values of DEBUG higher than 9 are for system experts usage only. You may get some weird screen output. Values larger than 5 cause an error to coredump, which can then be used with debug utilities like abd(1) and dbx(1).

error=

Specifies how many times the fatal error routine can be bypassed. The ERROR environment variable can also be set for this. The default, if neither of them present, is 0.

yapp=

Defines the device to which graphics output is send. Currently only interpreted for a limited number of yapp devices. Some yapp devices do not even listen to this keyword. Check yapp(5NEMO) or your local NEMO guru which one is installed. The default device is either 0 or the value set by the YAPP environment variable.