Unix command summary
A summary of the more frequently used commands on a Unix system. In this table, as in general, for most Unix commands, file, could be an actual file name, or a list of file names, or input/output could be redirected to or from the command.

Command/SyntaxWhat it will do
awk/nawk [options] filescan for patterns in a file and process the results
cat [options] fileconcatenate (list) a file
cd [directory]change directory
chgrp [options] group filechange the group of the file
chmod [options] filechange file or directory access permissions
chown [options] owner filechange the ownership of a file; can only be done by the superuser
chsh (passwd -e/-s) username login_shellchange the user's login shell (often only by the superuser)
cmp [options] file1 file2compare two files and list where differences occur (text or binary files)
compress [options] filecompress file and save it as file.Z
cp [options] file1 file2copy file1 into file2; file2 shouldn't already exist. This command creates or overwrites file2.
cut (options) [file(s)]cut specified field(s)/character(s) from lines in file(s)
date [options]report the current date and time
dd [if=infile] [of=outfile] [operand=value]copy a file, converting between ASCII and EBCDIC or swapping byte order, as specified
diff [options] file1 file2compare the two files and display the differences (text files only)
df [options] [resource]report the summary of disk blocks and inodes free and in use
du [options] [directory or file]report amount of disk space in use
echo [text string]echo the text string to stdout
ed or ex [options] fileUnix line editors
emacs [options] filefull-screen editor
expr argumentsevaluate the arguments. Used to do arithmetic, etc. in the shell.
file [options] fileclassify the file type
find directory [options] [actions]find files matching a type or pattern
finger [options] user[@hostname]report information about users on local and remote machines
ftp [options] hosttransfer file(s) using file transfer protocol
grep [options] 'search string' argument

egrep [options] 'search string' argument

fgrep [options] 'search string' argument

search the argument (in this case probably a file) for all occurrences of the search string, and list them.
gzip [options] file

gunzip [options] file

zcat [options] file

compress or uncompress a file. Compressed files are stored with a .gz ending
head [-number] filedisplay the first 10 (or number of) lines of a file
hostnamedisplay or set (super-user only) the name of the current machine
kill [options] [-SIGNAL] [pid#] [%job]send a signal to the process with the process id number (pid#) or job control number (%n). The default signal is to kill the process.
ln [options] source_file targetlink the source_file to the target
lpq [options]

lpstat [options]

show the status of print jobs
lpr [options] file

lp [options] file

print to defined printer
lprm [options]

cancel [options]

remove a print job from the print queue
ls [options] [directory or file]list directory contents or file permissions
mail [options] [user]

mailx [options] [user]

Mail [options] [user]

simple email utility available on Unix systems. Type a period as the first character on a new line to send message out, question mark for help.
man [options] commandshow the manual (man) page for a command
mkdir [options] directorymake a directory
more [options] file

less [options] file

pg [options] file

page through a text file
mv [options] file1 file2move file1 into file2
od [options] fileoctal dump a binary file, in octal, ASCII, hex, decimal, or character mode.
passwd [options]set or change your password
paste [options] filepaste field(s) onto the lines in file
pr [options] filefilter the file and print it on the terminal
ps [options]show status of active processes
pwdprint working (current) directory
rcp [options] hostnameremotely copy files from this machine to another machine
rlogin [options] hostnamelogin remotely to another machine
rm [options] fileremove (delete) a file or directory (-r recursively deletes the directory and its contents) (-i prompts before removing files)
rmdir [options] directoryremove a directory
rsh [options] hostnameremote shell to run on another machine
script filesaves everything that appears on the screen to file until exit is executed
sed [options] filestream editor for editing files from a script or from the command line
sort [options] filesort the lines of the file according to the options chosen
source file

. file

read commands from the file and execute them in the current shell. source: C shell, .: Bourne shell.
strings [options] filereport any sequence of 4 or more printable characters ending in <NL> or <NULL>. Usually used to search binary files for ASCII strings.
stty [options] set or display terminal control options
tail [options] filedisplay the last few lines (or parts) of a file
tar key[options] [file(s)]tape archiver--refer to man pages for details on creating, listing, and retrieving from archive files. Tar files can be stored on tape or disk.
tee [options] filecopy stdout to one or more files
telnet [host [port]]communicate with another host using telnet protocol
touch [options] [date] filecreate an empty file, or update the access time of an existing file
tr [options] string1 string2translate the characters in string1 from stdin into those in string2 in stdout
uncompress file.Zuncompress file.Z and save it as a file
uniq [options] fileremove repeated lines in a file
uudecode [file]decode a uuencoded file, recreating the original file
uuencode [file] new_nameencode binary file to 7-bit ASCII, useful when sending via email, to be decoded as new_name at destination
vi [options] filevisual, full-screen editor
wc [options] [file(s)]display word (or character or line) count for file(s)
whereis [options] commandreport the binary, source, and man page locations for the command named
which commandreports the path to the command or the shell alias in use
who or wreport who is logged in and what processes are running
zcat file.Zconcatenate (list) uncompressed file to screen, leaving file compressed on disk
(From an Introduction to Unix, University Technology Services, Ohio State University,1996.)