1.5. Beginner s Guide

1.5. Beginner's Guide

If you're just beginning to work on a Unix system, the abundance of commands might prove daunting. To help orient you, the following lists present a small sampling of commands on various topics.

1.5.1. Communication

ftp	Interactive file transfer program.
login	Sign on to Unix.
mailx	Read or send mail.
slogin	Sign on to remote Unix using secure shell.
ssh	Connect to another system, securely.

1.5.2. Comparisons

cmp	Compare two files, byte by byte.
comm	Compare items in two sorted files.
diff	Compare two files, line by line.
diff3	Compare three files.
dircmp	Compare directories.
sdiff	Compare two files, side by side.

1.5.3. File Management

cd	Change directory.
chgrp	Change file group.
chmod	Change access modes on files.
chown	Change file owner.
cksum	Print a file checksum, POSIX standard algorithm.
cp	Copy files.
csplit	Break files at specific locations.
file	Determine a file's type.
head	Show the first few lines of a file.
less	A sophisticated interactive pager program for looking at information on a terminal, one screenful (or "page") at a time. The name is a pun on the more program.
ln	Create filename aliases.
locate	Find a file somewhere on the system based on its name. The program uses a database of files that is usually automatically rebuilt, nightly.
ls	List files or directories.
md5sum	Print a file checksum using the Message Digest 5 (MD5) algorithm.
mkdir	Create a directory.
more	Display files by screenful.
mv	Move or rename files or directories.
pwd	Print working directory.
rm	Remove files.
rmdir	Remove directories.
scp	Copy files to remote system securely.
split	Split files evenly.
tail	Show the last few lines of a file.
wc	Count lines, words, and characters.

1.5.4. Miscellaneous

banner	Make posters from words.
bc	Arbitrary precision calculator.
cal	Display calendar.
calendar	Check for reminders.
clear	Clear the screen.
info	The GNU Info system for online documentation.
man	Get information on a command.
nice	Reduce a job's priority.
nohup	Preserve a running job after logging out.
passwd	Set your login password.
script	Produce a transcript of your login session.
spell	Report misspelled words.
su	Switch to a different user.

1.5.5. Printing (BSD Commands)

lpr	Send to the printer.
lpq	Get printer status.
lprm	Cancel a printer request.
pr	Format and paginate for printing.

1.5.6. Printing (System V Commands)

cancel	Cancel a printer request.
lp	Send to the printer.
lpstat	Get printer status.
pr	Format and paginate for printing.

1.5.7. Programming

cc	C compiler.
ctags	C function references (for vi).
ld	Loader.
lex	Lexical analyzer generator.
make	Execute commands in a specified order.
od	Dump input in various formats.
splint	C program analyzer.
strace	Trace signals and system calls.
strip	Remove data from an object file.
truss	Trace signals and system calls.
yacc	Parser generator. Can be used with lex.

1.5.8. Searching

egrep	Extended version of grep.
fgrep	Search files for literal words.
find	Search the system for filenames matching patterns or attributes.
grep	Search files for text patterns.
strings	Display text strings found in binary files.

1.5.9. Shells

Bourne family shells:

bash	The GNU Project's Bourne Again Shell.
ksh	The Korn shell, either an original or clone, depending upon the operating system.
pdksh	The Public Domain Korn shell.
sh	The original Bourne shell, particularly on commercial Unix systems.
zsh	The Z-shell.

C shell family shells:

csh	The original BSD C shell.
tcsh	The "Tenex" C shell: a much-enhanced version of csh.

1.5.10. Shell Programming

basename	Print the last component of a pathname, optionally removing a suffix.
dirname	Print all but the last component of a pathname.
echo	Repeat command-line arguments on the output.
expr	Perform arithmetic and comparisons.
id	Print user and group ID and name information.
line	Read a line of input.
printf	Format and print command-line arguments.
sleep	Pause during processing.
test	Test a condition.

1.5.11. Storage

bunzip2	Expand files compressed with bzip2 (.bz2 files).
bzip2	Very high quality file compression program.
cpio	Copy archives in or out.
gunzip	Expand compressed (.gz and .Z) files.
gzcat	Display contents of compressed files (may be linked to zcat).
gzip	Compress files to free up space.
tar	File tree and tape archiver.
zcat	Display contents of compressed files.

1.5.12. System Status

at	Execute commands later.
crontab	Automate commands.
date	Display or set date.
df	Show free disk space.
du	Show disk usage.
env	Show environment variables.
finger	Display information about users.
kill	Terminate a running command.
ps	Show processes.
stty	Set or display terminal settings.
who	Show who is logged on.

1.5.13. Text Processing

awk	A pattern-matching programming language for working with text files.
cat	Concatenate files or display them.
cut	Select columns for display.
ex	Line editor underlying vi.
fmt	Produce roughly uniform line lengths.
iconv	General-purpose character-encoding conversion tool.
join	Merge different columns into a database.
paste	Merge columns or switch order.
sed	Noninteractive text editor.
sort	Sort or merge files.
tr	Translate (redefine) characters.
uniq	Find repeated or unique lines in a file.
vi	Visual text editor.
xargs	Process many arguments in manageable portions.