intro - introduction to host and satellite commands
This section describes host commands, satellite commands, and
satellite utilities. Host commands are special utilities (in addition
to the standard UNIX utilities) that are invoked with logged into the
host system. These include
Satellite commands are invoked when communicating with the ELF
satellite monitor that serves as the interface between the user and
the satellite. The monitor supplies commands for managing satellite
cat, cd, chmod, chsize, cp, create, df, ls, mv, pwd, rm, quit
), for communicating with the host (
), and for executing application programs (
). An additional command (
) gives a synopsis of all the satellite commands.
Satellite utility programs include
makefsys, diskcp, garead,
SATELLITE FILE SYSTEM
The satellite file system is organized (like the UNIX system) in a
tree structure. At the top level is the root directory named . (dot).
Thirty permanent directories exist on the level directly below the
root. Twenty-nine directories are initially named
/d0, /d1, /d2, ..., /d28
; the thirtieth directory is named
and contains system programs such as
All files in the file system exist in these thirty directories.
Unlike the UNIX system it is not possible to create any new
directories; it is also not possible to create files in the root
directory. To guarantee fast disk access during real-time processing
this system requires that contiguous blocks be allocated to a file and
therefore that a maximum limit be set on the size of a file when it is
Directory and File Names
Directory names can be up to 10 characters long; file names can be up
to 12 characters long. These characters may selected from the set of
all character values excluding 0 (nul) and the ASCII code for /
(slash). The first character of a name must not be an exclamation
point (!) which is the prefix that signifies a host path hame.
A path name is a null-terminated character string constructed as
If a path name begins with a slash, the path search begins at the root
directory. Otherwise, the search occurs in the current working
directory. A slash by itself names the root directory; a slash
followed by a directory names a directory. A file is named either by
a file name (indicating a file in the current working directory), or
by a slash followed by a directory name, another slash, and a file
HOST FILE REFERENCES
In order to distinguish between host files and satellite files it is
necessary to prefix the path name of host files with an exclamation
point (!). On satellites that have local file systems all path names
that begin with ! refer to host files, while pathnames without ! refer
to satellite files. On stallites that do not have a local file
system, all path names (with or without !) refer to host files. For a
complete description of UNIX host file names and path names see
intro(2) in the UNIX User's Manual.
Host commands follow the syntax described in intro(1) of the
UNIX User's Manual.
When the ELF program or any other PARASITE-FS program begins, three
files are automatically opened. These files are the standard input,
standard output, and standard error (see
Normally these files are associated with the console terminal
(i.e. standard input comes from the terminal keyboard and standard
output and error is printed on the terminal). But standard input and
standard output may also be redirected to files. On a command line,
cmdname < foo
means that the command reads the standard input from file
cmdname > foo
means that the command writes the standard input to file
cmdname >> foo
means that the command appends the standard output to file
Unless otherwise noted, satellite commands described in this section
accept options and other arguments according to the syntax that
name [options(s)] [cmdard(s)]
The name of an ELF command. You need specify only as many letters of
the command name as necessary to distinguish it from other command
names and from names of executable programs residing on the file
A single letter representing an option.
Path name or other command argument.
- "path name"
Path name generally refers to a file on the satellite system. The
path name syntax is described above. Where specially noted, path name
can also refer to
devices or host files. Path names for host files are described in
Note that path names for host files always begin with a ! to
distinguish them from satellite files.