HELP(1) OpenBSD Reference Manual HELP(1)NAMEhelp - help for new users and administrators
DESCRIPTION
This document is meant to familiarize new users and system administrators
with OpenBSD and, if necessary, UNIX in general.
Firstly, a wealth of information is contained within the system manual
pages. In UNIX, the man(1) command is used to view them. Type man man
for instructions on how to use it properly. Pay especially close
attention to the -k option.
Other OpenBSD references include the FAQ (Frequently Asked Questions)
located at http://www.openbsd.org/faq, 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
http://www.openbsd.org/mail.html.
System administrators should have already read the afterboot(8) 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.
The Unix shell
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; OpenBSD ships with csh(1), ksh(1), and sh(1). Each user's
shell is indicated by the last field of their corresponding entry in the
system password file (/etc/passwd).
Basic Unix commands
man 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.
pwd 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 located.
cd Change working directory. Use this command to navigate
throughout the file hierarchy. For example, type cd / to
change the working directory to the root.
ls List directory contents. Type ls -l for a detailed listing.
cat Although it has many more uses, cat filename will print the
contents of a plain-text file to the screen.
mkdir Make a directory. For example, mkdir foobar.
rmdir Remove a directory.
rm Remove files. Files are generally only removable by their
owners. See the chmod(1) command for information on file
permissions.
chmod 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.
cp Copy files.
mv Move and rename files.
ps 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 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).
date Print the current system date and time.
mail Access mailbox.
exit 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 within the PATH environment variable (see environ(7)). 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
which(1) and ``whence'', a ksh(1) built-in command, can be used to see
what commands are being executed.
SEE ALSOcsh(1), ksh(1), man(1), whatis(1), whereis(1), which(1), afterboot(8)HISTORY
This manual page was written by Aaron Campbell <aaron@openbsd.org> and
first appeared in OpenBSD 2.6.
OpenBSD 4.9 January 11, 2008 OpenBSD 4.9
