Appendix A. Unix Reference

In this appendix, you’ll find a fairly thorough reference on Unix commands and flags as well as examples and descriptions of each. We organized this appendix to generally parallel the book, so that you can easily reference key commands and related flags without being overwhelmed with long lists of commands.

Table A.a summarizes what you’ll find in this appendix.

Tables A.1–A.15 contain commands and flags that relate to the topics covered by the similarly numbered chapter (Chapters 16 and 17 do not introduce many new commands, so the commands from those chapters are included with similar commands in the other appendixes). In addition to the commands and flags discussed in the chapters, you’ll also find related commands and options that you might find useful in your Unix adventures, reference information that will jog your memory, and ideas to help you get off and running on additional projects. If you’re looking for a thorough command flag reference, check out Appendix C.

Table A.1. Getting Started with Unix: Survival Skills

COMMAND	DESCRIPTION
apropos keyword	Find appropriate man pages for keyword.
cat file	Display file contents onscreen or provide file contents to standard output.
cat file1 file2	Display file1 and file2.
cd	Return to your home directory from anywhere in the Unix system.
cd ..	Move up one level in the directory tree.
cd /etc	Change to the /etc directory relative to the system root.
cd ~/subdir	Use a tilde (~) as a handy shortcut for your home directory.
cd Projects	Move to the Projects directory relative to the current directory.
col -b	Filter backspaces and reverse line feeds out of input. Use to make man pages editable without odd formatting.
	Close your current process (often a shell) and your Unix session if you close the login shell.
exit	Close your current shell and your Unix session if you’re in the login shell.
less file	Use to view file screen by screen.
logout	Close your Unix session.
ls	List files and directories.
ls /	List the files and directories in the root directory.
ls directory	List the files and directories in directory.
ls -a	List all files and directories, including hidden ones.
ls -c	List files and directories by modification date.
ls -l	List files and directories in long format, with extra information.
ls -lh	List files and directories in long format, with extra information and human readable sizes.
man 5 command	View the specified section (5) of the man pages for command. Sometimes used as man -s 5 command.
man command	View the manual (help) pages for command.
man -k keyword	Find appropriate man pages for keyword.
more filetoview	View filetoview screen by screen.
passwd	Change your password.
pwd	Display the path and name of the directory you are currently in.
reset	Reset the shell to fix display problems.
stty sane	Try to fix unexpected, sudden, and strange display problems.
su - yourid	Relog in without having to log out.
su	Become the root user.
sudo command	Run command with the authority of the root user.

Table A.3. Working with Your Shell

COMMAND	DESCRIPTION
!10	Rerun command 10 from the history list in csh or zsh.
bash	Start a bash subshell or run a bash script.
chsh	Change your shell.
csh	Start a csh (C) subshell or run a csh shell script.
echo $SHELL	Display the value of the $SHELL environment variable.
exit	Leave the current shell and return to the previous one, or log out of the login shell.
history	View a numbered list of previous commands.
ksh	Start a ksh (Korn) subshell or run a ksh shell script.
r 2	Repeat a specific command in ksh from the history output (in this case command 2).
set -o emacs	Enable command completion with emacs commands in the ksh shell.
set -o vi	Enable command completion with vi commands in the ksh shell.
sh	Start a sh (Bourne) subshell or run a sh shell script.
stty erase '^?'	Make erase characters to the left of the cursor.
stty erase '^H'	Make erase characters to the left of the cursor. Type stty erase then press .
su - yourid	Start a new login shell as yourid.
su user	Switch user to user.
tcsh	Start a tcsh subshell or run a tcsh shell script.
zsh	Start a zsh subshell or run a zsh shell script.

alias ourterm="longhonking
 → command -w -many –flags
 → arguments"

Table A.9. Running Scripts and Programs

COMMAND	DESCRIPTION
at 01:01 1 Jan 2004	Schedule a job or jobs to run at 01:01 on January 1, 2004.
at 01/01/04	Schedule a job to run on 1/1/04.
at 3:42am	Schedule a job to run at 3:42 a.m.
at noon tomorrow	Schedule a job to run at noon tomorrow.
at now + 3 weeks	Schedule a job to run in three weeks.
at teatime	Schedule a job to run at 4 p.m.
atq	Review jobs in the at queue.
atrm 3	Remove the specified queued job (3, in this case).
batch	Schedule jobs to run when system load permits.
bg	Run the most recently suspended or controlled job in the background.
bg %2	Run job 2 in the background.
crontab -e	Edit your crontab in the default editor to schedule regular processes or jobs.
	Suspend a running job, program, or process.
fg	Run the most recently suspended or controlled job in the foreground.
fg 1	Run job 1 in the foreground.
jobs	See a list of the currently controlled jobs.
kill %ftp	Kill a job by name or job number.
kill 16217	Kill process number 16217.
kill -9 16217	Kill process 16217; the -9 flag lets you kill processes that a regular kill won’t affect.
nice	Run a job “nicely”—slower and with less of an impact on the system and other users.
	Bigger numbers are nicer, up to 19. 10 is the default.
nice -n 19 slowscript	Run slowscript nicely with a priority of 19.
pkill badjob	Kill the process called badjob.
ps	View the list of current processes that you’re running
ps -e	View all processes, including those from other users.
ps -f	View processes and their interrelationships (the forest view).
ps -x	View the processes that the system itself is running (also called daemons).
renice 19 processid-of → -slowscript	Run slowscript more nicely (change the niceness) with a priority of 19.
time script	Time how long it takes (in real time and system time) to run script.
top	Monitor system load and processes in real time.