Linux in a Nutshell, Third Edition

Beginner’s Guide

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

Communication

ftp	File Transfer Protocol.
login	Sign on.
rlogin	Sign on to remote system.
rsh	Run shell or single command on remote system.
talk	Exchange messages interactively with other terminals.
telnet	Connect to another system.
tftp	Trivial file transfer protocol.
uudecode	Decode file prepared for mailing by uuencode.
uuencode	Encode file containing binary characters for mailing.
vacation	Respond to mail automatically.

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.

File Management

cat	Concatenate files or display them.
chfn	Change user information for finger, email, etc.
cksum	Compute checksum.
chmod	Change access modes on files.
chsh	Change login shell.
cp	Copy files.
csplit	Break files at specific locations.
dd	Copy files in raw disk form.
file	Determine a file’s type.
head	Show the first few lines of a file.
less	Display files by screenful.
ln	Create filename aliases.
ls	List files or directories.
merge	Merge changes from different files.
mkdir	Create a directory.
more	Display files by screenful.
mv	Move or rename files or directories.
newgrp	Change current group.
pwd	Print working directory.
rcp	Copy files to remote system.
rm	Remove files.
rmdir	Remove directories.
split	Split files evenly.
tail	Show the last few lines of a file.
wc	Count lines, words, and characters.

Printing

lpq	Show status of print jobs.
lpr	Send to the printer.
lprm	Remove print job.
lpstat	Get printer status.
pr	Format and paginate for printing.

Programming

ar	Create and update library files.
as	Generate object file.
bison	Generate parsing tables.
cpp	Preprocess C code.
flex	Lexical analyzer.
g++	GNU C++ compiler.
gcc	GNU C compiler.
ld	Link editor.
m4	Macro processor.
make	Create programs.
ranlib	Regenerate archive symbol table.
rpcgen	Translate RPC to C code.
yacc	Generate parsing tables.

Program Maintenance

cvs	Manage different versions (revisions) of source files.
etags	Generate symbol list for use with the Emacs editor.
gctags	Generate symbol list for use with the vi editor.
gdb	GNU debugger.
gprof	Display object file’s profile data.
imake	Generate makefiles for use with make.
make	Maintain, update, and regenerate related programs and files.
nm	Display object file’s symbol table.
patch	Apply patches to source code.
rcs	Manage different versions (revisions) of source files.
size	Print the size of an object file in bytes.
strace	Trace system calls and signals.
strip	Strip symbols from an object file.

Searching

apropos	Search manpages for topic.
egrep	Extended version of grep.
fgrep	Search files for literal words.
find	Search the system for filenames.
grep	Search files for text patterns.
strings	Search binary files for text patterns.
whereis	Find command.

Shell Programming

echo	Repeat command-line arguments on the output.
expr	Perform arithmetic and comparisons.
printf	Format and print command-line arguments.
sleep	Pause during processing.
test	Test a condition.

Storage

bzip2	Compress files to free up space.
cpio	Create and unpack file archives.
gunzip	Expand compressed (.gz and .Z) files (preferred).
gzip	Compress files to free up space.
shar	Create shell archive.
tar	Copy files to or restore files from an archive medium.
zcat	Display contents of compressed files.

System Status

at	Execute commands later.
atq	Show jobs queued by at.
atrm	Remove job queued by at.
chgrp	Change file group.
chown	Change file owner.
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.
printenv	Show environment variables.
ps	Show processes.
stty	Set or display terminal settings.
who	Show who is logged on.

Text Processing

col	Process control characters.
cut	Select columns for display.
ex	Line editor underlying vi.
expand	Convert tabs to spaces.
fmt	Produce roughly uniform line lengths.
fold	Break lines.
gawk	Process lines or records one by one.
ghostscript	Display PostScript or PDF file.
groff	Format troff input.
ispell	Interactively check spelling.
join	Merge different columns into a database.
paste	Merge columns or switch order.
rev	Print lines in reverse.
sed	Noninteractive text editor.
sort	Sort or merge files.
tac	Print lines in reverse.
tr	Translate (redefine) characters.
uniq	Find repeated or unique lines in a file.
vi	Visual text editor.
xargs	Process many arguments in manageable portions.

Miscellaneous

banner	Make posters from words.
bc	Arbitrary precision calculator.
cal	Display calendar.
clear	Clear the screen.
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.
su	Become a superuser.
tee	Simultaneously store output in file and send to screen.
which	Print pathname of a command.