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.

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