man/man1/help.1

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.Dd $Mdocdate: March 27 2015 $
.Dt HELP 1
.Os
.Sh NAME
.Nm help
.Nd help for new users and administrators
.Sh DESCRIPTION
This document is meant to familiarize new users and system administrators with
.Ox
and, if necessary,
.Ux
in general.
.Pp
Firstly, a wealth of information is contained within the system manual pages.
In
.Ux ,
the
.Xr man 1
command is used to view them.
Type
.Ic man man
for instructions on how to use it properly.
Pay especially close attention to the
.Fl k
option.
.Pp
Other
.Ox
references include the FAQ (Frequently Asked Questions) located at
.Lk http://www.openbsd.org/faq ,
which is mostly intended for administrators and assumes the reader possesses
a working knowledge of
.Ux .
There are also mailing lists in place where questions are fielded by
.Ox
developers and other users; see
.Lk http://www.openbsd.org/mail.html .
.Pp
System administrators should have already read the
.Xr 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.
.Ss 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;
.Ox
ships with
.Xr csh 1 ,
.Xr ksh 1 ,
and
.Xr sh 1 .
Each user's shell is indicated by the last field of their corresponding entry
in the system password file
.Pf ( Pa /etc/passwd ) .
.Ss Basic Unix commands
.Bl -tag -width "chmodXXX"
.It Cm man
Interface to the system manual pages.
For any of the commands listed below, type
.Ic man <command>
for detailed information on what it does and how to use it.
.It Cm pwd
Print working directory.
Files are organized in a hierarchy (see
.Xr hier 7 )
called a tree.
This command will indicate in which directory you are currently located.
.It Cm cd
Change working directory.
Use this command to navigate throughout the file hierarchy.
For example, type
.Ic cd /
to change the working directory to the root.
.It Cm ls
List directory contents.
Type
.Ic ls -l
for a detailed listing.
.It Cm cat
Although it has many more uses,
.Ic cat filename
will print the contents of a plain-text file to the screen.
.It Cm mkdir
Make a directory.
For example,
.Ic mkdir foobar .
.It Cm rmdir
Remove a directory.
.It Cm rm
Remove files.
Files are generally only removable by their owners.
See the
.Xr chmod 1
command for information on file permissions.
.It Cm 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.
.It Cm cp
Copy files.
.It Cm mv
Move and rename files.
.It Cm ps
List active processes.
Most
.Ux Ns -based
operating systems, including
.Ox ,
are multitasking, meaning many programs share system resources at the same
time.
A common usage is
.Ic ps -auxw ,
which will display information about all active processes.
.It Cm 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).
.It Cm date
Print the current system date and time.
.It Cm mail
Access mailbox.
.It Cm exit
Log out of the system.
.El
.Pp
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
.Ev PATH
environment variable (see
.Xr 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.
.Pp
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
.Xr which 1
and
.Dq whence ,
a
.Xr ksh 1
built-in command,
can be used to see what commands are being executed.
.Sh SEE ALSO
.Xr csh 1 ,
.Xr ksh 1 ,
.Xr man 1 ,
.Xr whatis 1 ,
.Xr whereis 1 ,
.Xr which 1 ,
.Xr afterboot 8
.Sh HISTORY
This manual page was written by
.An Aaron Campbell Aq Mt aaron@openbsd.org
and first appeared in
.Ox 2.6 .