— help for
new users and administrators
This document is meant to familiarize new users and system administrators with
and, if necessary,
Firstly, a wealth of information is contained within the system manual pages. In
command is used to view
them. Type man man
for instructions on how to use
it properly. Pay especially close attention to the
references include the FAQ (Frequently
Asked Questions) located at
which is mostly intended for administrators and assumes the reader possesses a
working knowledge of UNIX
. There are also mailing
lists in place where questions are fielded by OpenBSD
developers and other users; see
System administrators should have already read the
man page which
explains a variety of tasks that are typically performed after the first
system boot. When configuring any aspect of the system, first consider any
possible security implications your changes may have.
After logging in, some system messages are typically displayed, and then the
user is able to enter commands to be processed by the shell program. The shell
is a command-line interpreter that reads user input (normally from a terminal)
and executes commands. There are many different shells available;
. Each user's shell is
indicated by the last field of their corresponding entry in the system
password file (/etc/passwd
- Interface to the system manual pages. For any of the
commands listed below, type man
command for detailed information on what
it does and how to use it.
- Print working directory. Files are organized in a hierarchy
(see hier(7)) called a tree.
This command will indicate in which directory you are currently
- Change working directory. Use this command to navigate
throughout the file hierarchy. For example, type
cd / to change the working directory to the
- List directory contents. Type ls
-l for a detailed listing.
- Although it has many more uses,
will print the contents of a plain-text file to the screen.
- Edit text files. For example,
See also mg(1).
- Make a directory. For example,
- Remove a directory.
- Remove files. Files are generally only removable by their
owners. See the chmod(1)
command for information on file permissions.
- Change file modes, including permissions. It is not
immediately obvious how to use this command; please read its manual page
carefully, as proper file permissions, especially on system files, are
vital in maintaining security and integrity.
- Copy files.
- Move and rename files.
- List active processes. Most
UNIX-based operating systems, including
OpenBSD, are multitasking, meaning many programs
share system resources at the same time. A common usage is
ps -auxw, which will display information
about all active processes.
- Kill processes. Used mostly for terminating
run-away/unresponsive programs, but also used to signal programs for
requesting certain operations (e.g., re-read their configuration).
- Print the current system date and time.
- Access mailbox.
- Log out of the system.
When a command is entered, it is first checked to see if it is built-in to the
shell. If not, the shell looks for the command in any directories contained
environment variable (see
). If the command is
not found, an error message is printed. Otherwise, the shell runs the command,
passing it any arguments specified on the command line.
Shell built-in commands do not have their own manual page, so it's necessary to
read the manual page for the user's shell. Tools such as
“whence”, a ksh(1)
built-in command, can be used to see what commands are being executed.
This manual page was written by Aaron
and first appeared in OpenBSD 2.6