NAME

intro − introduction to system administration commands

DESCRIPTION

This chapter of the DOMAIN/IX Programmer’s Reference for BSD4.2 contains commands and programs that perform miscellaneous system maintenance and administration functions.  These commands are specific to the BSD4.2-based portions of the DOMAIN/IX SR9 software.  The chapter (and the commands) are labeled with the number 8, both to distinguish the commands from those in the DOMAIN/IX Command References, and to maintain some continuity with the numbering scheme of the original UNIX Programmers’ Manuals. However, the pages are numbered in the from 1M-n, where n is the command’s page number in the chapter. 

The chapter also includes reference documentation for many of the commands and programs that perform and manage network communications ( telnet, uucp, and internet), as well as various servers and daemons for remote command execution. 

You must be logged in as the super-user to use many of these utilities. 

Each command returns two status bytes when it terminates.  One of these bytes, which explains the cause for the command’s termination, is supplied by the system.  (The system returns zero for normal termination).  When a command terminates normally, it also supplies a status byte, which is usually zero to indicate successful execution and not zero to report any problems encountered.  See wait(2) and exit(2) for detailed information. 

GLOSSARY

Process ID

Each active process in the system is uniquely identified by a positive integer called a process ID.  The range of this ID is from zero to 30,000. 

Parent Process ID

A new process is created by a currently active process; see fork(2).  The parent process ID of a process is the process ID of its creator. 

Process Group ID

Each active process is a member of a process group that is identified by a positive integer called the process group ID.  This ID is the process ID of the group leader.  This grouping permits the signaling of related processes; see kill(2). 

Tty Group ID

Each active process can be a member of a terminal group that is identified by a positive integer called the tty group ID.  This grouping is used to terminate a group of related process upon termination of one of the processes in the group; see exit(2) and signal(2). 

Real User ID and Real Group ID

Each user allowed on the system is identified by a positive integer called a real user ID. 

Each user is also a member of a group.  The group is identified by a positive integer called the real group ID. 

An active process has a real user ID and real group ID that are set to the real user ID and real group ID, respectively, of the user responsible for the creation of the process. 

Effective User ID and Effective Group ID

An active process has an effective user ID and an effective group ID that are used to determine file access permissions (see below).  The effective user ID and effective group ID are equal to the process’s real user ID and real group ID respectively, unless the process or one of its ancestors evolved from a file that had the set-user-ID bit or set-group-ID bit set; see exec(2). 

Super-user

A process is recognized as a super-user process and is granted special privileges if its effective user ID is zero. 

Special Processes

The processes with a process ID of zero and a process ID of one are special processes and are referred to as proc0 and proc1. 

Proc0 is the scheduler.  Proc1 is the initialization process (init).  Proc1 is the ancestor of every other process in the system and is used to control the process structure. 

File Name.

Names consisting of up to 32 characters may be used to name an ordinary file, special file or directory. 

These characters may be selected from the set of all character values excluding zero (null) and the ASCII code for / (slash). 

Note that it is generally unwise to use *, ?, [, or ] as part of file names, because of the special meaning attached to these characters by the Shell.  See sh(1). 

Path Name and Path Prefix

A path name is a null-terminated character string starting with an optional slash (/), followed by zero or more directory names separated by slashes, optionally followed by a file name. 

More precisely, a path name is a null-terminated character string constructed as follows:

<path-name>::=<file-name>│<path-prefix><file-name>|/
<path-prefix>::=<rtprefix>│/<rtprefix>
<rtprefix>::=<dirname>/│<rtprefix><dirname>/

where <file-name> is a string of 1 to 32 characters other than the ASCII slash and null, and <dirname> is a string of 1 to 32 characters (other than the ASCII slash and null) that names a directory. 

If a path name begins with a slash, the path search begins at the root directory.  Otherwise, the search begins from the current working directory. 

A slash by itself names the root directory. 

Unless specifically stated otherwise, the null path name is treated as if it named a non-existent file. 

Directory

Directory entries are called links.  By convention, a directory contains at least two links, .  and .., referred to as dot and dot-dot respectively.  Dot refers to the directory itself and dot-dot refers to dot’s parent directory. 

Root Directory and Current Working Directory

Each process has associated with it a concept of a root directory and a current working directory for the purpose of resolving path name searches.  A process’s root directory need not be the root directory of the root file system. 

File Access Permissions

Read, write, and execute/search permissions on a file are granted to a process if one or more of the following is true:

The process’s effective user ID is super-user. 

The process’s effective user ID matches the user ID of the owner of the file and the appropriate access bit of the “owner” portion (0700) of the file mode is set. 

The process’s effective user ID does not match the user ID of the owner of the file, and the process’s group ID matches the group of the file and the appropriate access bit of the “group” portion (070) of the file mode is set. 

The process’s effective user ID does not match the user ID of the owner of the file, and the process’s effective group ID does not match the group ID of the file, and the appropriate access bit of the “other” portion (07) of the file mode is set. 

Otherwise, the corresponding permissions are denied.