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 qcc, link, and plint.

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 files ( cat, cd, chmod, chsize, cp, create, df, ls, mv, pwd, rm, quit ), for communicating with the host ( hcu ), and for executing application programs ( exec ). An additional command ( help ) gives a synopsis of all the satellite commands.

Satellite utility programs include makefsys, diskcp, garead, and boot.


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 /sys and contains system programs such as elf and makefsys. 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 created.

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.

Path Name
A path name is a null-terminated character string constructed as follows:

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 name.


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 stdio(3P)). 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 foo ;
cmdname > foo
means that the command writes the standard input to file foo ;
cmdname >> foo
means that the command appends the standard output to file foo. Unless otherwise noted, satellite commands described in this section accept options and other arguments according to the syntax that follows.
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 system.


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 /dev/tty or /dev/con devices or host files. Path names for host files are described in intro(2F). Note that path names for host files always begin with a ! to distinguish them from satellite files.