Unix Commands Quick Reference

cat filename1 > filename2 :
This overwrite contents of filename2 with filename1

cat filename1 » filename2 :
This appends contents of filename1 to filename2.

cd /usr:
Changes current directory to /usr directory

cd .. :
Change current directory to previous higher directory.

cd :
Change to home of current userid.

chgrp group1 filename1 :
Change group id to group 1 for filename1.

chgrp -R group1 * :
Changes group id of all files in current and subdirectories to group 1.

chmod ugo+rwx filename1:
Add read/write/execute permission to filename1 for user/owner, group and others (world).

chmod o x filename1 :
Remove execute from others (world)

chmod 751 filename1 :
Set rwx for user/owner, group and others; r=4, w=2, x=1, rwx=7 rx=5, rw=6, wx=3, none=0.

chown sam filename1 :
Change owner of file filename1 to sam.

chown -R sam * :
Change owner to sam for all files in current and subdirectories.

clear :
Clear the terminal screen.

compress filename1 :
Compress file filename1 and replace it with filename1.Z

cp filename1 filename2 :
Copy file filename1 to filename2 destroying the contents of filename2.

cp -i * /usr/local/bin :
Copy all files in current directory to /usr/local/bin directory; Prompt before overwriting files (i)

cpio :
Copy file archives to disk/tape

crontab -e :
Edit crontab file for current user

crontab -e bill :
Edit crontab file for user bill

crontab -l :
List crontab entries for current userid

csh :
Start the c shell process

cut -d:
-f1,5 /etc/passwd :
Extract the 1st and 5th fields (username & real name) from file /etc/passwd where delimiter is colon

who | cut -d" " -f1:
List login names from who command

date :
Display current date string

date +%D :
Display current date, MM/DD/YY format

dd :
Copy file(s) to/from raw devices

df :
Displays free disk blocks and modes on file systems.

df -k :
Displays free space in kilobytes for mounted file systems

echo name :
Displays literal "name" on screen

echo $PATH :
Displays PATH environment variable

ed/edit/ex :
Alternative line editors, see vi

env Displays current environment variables or allows setting

file filename1 :
Determines and displays type of file for filename1 (text, data, executable, directory, symbolic link...etc...)

find /usr/opt/bin -name "filename1*" -print :
Starts searching in /usr/opt/bin for files starting with

filename1, If found prints the full file names and continues searching subdirectories

find . -type f -print | xargs grep -i [PATTERN] :
Recursive grep for a pattern in a file (searches through files in subdirectories)

find . ! -mtime - | /usr/bin/xargs rm -rf :
Finds and removes files older than specified

finger sam :
Displays data about user session for sam

ftp solar :
Establishes a File Transfer Protocol session over the network between current host and a host named solar; See man pages for additional ftp commands

grep jdoe /etc/passwd :
Searches the file /etc/passwd searching for string "jdoe"; If found, displays

grep -i Sam filename1:
Search filename1 for upper or lower case string of Sam and display lines found

groups sam :
List groups that sam is a member of

head filename1 :
Display first few lines of filename1

head -50 filename1:
Display first fifty lines of filename1

id :
List current user id and any group ids

kill -9 1351 :
Terminate process number 1351

ksh:
Start Korn Shell command interpreter; See man pages; Preferred shell for most users

ln -s filename1 /usr/opt/filename2 :
Create a symbolic link named /usr/opt/filename2 that points to filename1; See man pages

lp -d lp1 filename1 :
Print filename1 on destination printer lp1

lpstat -d :
Displays name of default printer, if any

lpstat -a :
Lists printers accepting print requests

lpstat -s :
Displays most everything regarding printing

lpstat -u sam :
Displays status of sam's print jobs

ls -al :
Displays all files in wide listing

ls -al *.doc :
Displays files ending with .doc

ls -al /bin/k*:
Displays files starting with k in /bin directory

man --is Online UNIX manual:

man-pages:
It gives detailed instructions on all of the commands listed here and a lot more.See man man for more...

mail sam :
Starts mail message to sam

mailx sam :
Nicer looking mail utility

mkdir -p /usr/opt/dirx:
Creates dirx below /usr/opt

make:
Code compilation utility

mkdir dirx:
Creates directory dirx

more filename1 :
Displays single pages from filename1 pausing after each page.for many options see man pages

mv filename1 /usr/opt/ :
Moves filename1 to directory /usr/opt; Unlike the cp (copy) command, mv removes file from origin

netstat -i:
Show the TCP/IP network interfaces

netstat -r:
Show network route table

netstat -rn:
Displays routing information but bypasses hostname lookup

netstat -a | more :
Show the state of all sockets

newgrp group1 :
Changes current group to group 1

news :
Displays unread files from /usr/news or /var/news

nice/renice :
Adjusts process’ execution priority

Unix Commands from p to z:

passwd:
Allows changing your login password

ps :
Lists all of current user's live processes

ps -ef :
List all users processes that are executing

pwd:
Displays current working directory you are in

rcp filename1 hostb:
/usr/local/bin :
Copies filename1 from current host system to hostb, and places it in the /usr/local/bin directory; The .rhosts or hosts.equiv files must be setup to allow action

rksh:
Starts restricted Korn Shell session

rlogin hostb :
Logs into remote host name hostb

rm filename1 :
Deletes filename1 from the disk without recourse

rm -i filename1 :
Deletes filename1 after prompting for verification

rmdir dirx :
Deletes directory dirx

rmdir -r dirx:
Deletes directory and all contents

rsh:
Restricted version of Bourne Shell for security

sar :
System Activity Reporter

sh :
Bourne Shell command interpreter; Alternative to Korn Shell and C shell but is the default on most systems; Older version that is losing popularity

sleep 3 :
Pauses for 3 seconds and continues

stty sane:
Attempts to restore terminal settings after they are hosed; Use CTRL-J with this command

stty erase ^H :
Use to reset backspace/delete; ^H is the key you may want to use for backspace/delete;

su sam:
Log on as user sam

su - sam:
Log on as sam, and execute his profile too

tail filename1 :
Display last few lines of filename1

tail -50 filename1 :
Display last fifty lines of filename1

tail -f :
Continually reads updating file; Great for monitoring a log file while being written

tar -cvf /dev/rmt/0c /usr/bin/* :
Tape archive utility; Copies all files in /usr/bin directory to tape device /dev/rmt/

tar -xvf /dev/rmt/0 /usr/bin/ :
Extracts all files from tape device /dev/rmt/0 and writes them to /usr/bin/

tar -tvf /dev/rmt/0c :
Read tape on device /dev/rmt/0c and lists contents in verbose mode

tee:
Used in scripts to split output to two outputs. Usually used with a pipe command (|)

tee -a /tmp/filename1:
Append the output to filename1 without overwriting its original content

telnet hostb:
Create a remote terminal on hostb

touch filename1 :
Creates an empty file named filename1; Changes modification time to current time if the file already exists

uname -a:
Lists 0/S revision, host name, hardware

uncompress filename1 :
Uncompresses file with .Zsuffix, created by compress command previously

uptime :
Displays current time, time logged-in,number of users etc

users:
Displays current logged-in users in a listing

uucp :
UNIX-to-UNIX copy utility; See man pages

view filename1:
A read only version of vi editor

w :
Combination of uptime, who and ps -a commands

wall :
Write to all; Allows entry of message to be sent to line 25 of all terminals; End message with a CTRLD command

wc -l filename1:
Utility that counts the number of lines in filename1

wc -c filename1 :
Utility that counts the number of bytes in filename1; -m provides number of characters

wc -w filename1 :
Utility that counts the number of the words in filename1

whence filename2:
Prints path name location of executable filename2

which filename2 :
Similar to whence command

who Displays login name, terminal name, date, and time of login, of users currently logged in

who am i :
Displays effective user id of user

who -b :
Displays date/time of last reboot

who -r :
Displays current system run level