Commands	Description	
cal 	Display calendar
cal  [[month] year]
cal 9 2002
cal 2002	
cat 	Concatenate, copy and print files
cat file(s)
cat file1 file2 file3 > outfile
cat > outfile (or cat - > outfile)
input from keyboard until ^d
cat –s file1 filex  (silence option, if filex not exist, it will not display error mesg)	
cd 	Change working directory
cd  pathname
cd    (cd to home)
cd ~UID
cd ../path/	
chmod 	Change file mode access permissions
chmod a=rx,u+w file(s)
chmod u=rwx,g=r,o=rx *  (include dir too)
chmod 755 file(s)	
clear 	Clear terminal screen	
compress   	Compress file(s)
compress file(s)	
cp 	Copy files and directory subtrees
cp filetarget filedest
cp files(s) dir
cp dir dirdest	
date 	Display system date time	
df 	Display file system info	
diff 	Compare 2 files	
du 	Summarize disk usage  (size usage of each directory)	
echo 	Display string to the terminal	
exit 	Terminate process	
file file(s)	Determine file type (ascii, command, directory, etc…)	
finger 	Display user information in the system	
grep 	Search a file for a pattern
grep –c file(s)
grep –l file(s)
grep –n file(s)
grep –i file(s)
grep –h file(s)
grep –v file(s)	
head 	Display first few lines
head file  (first 10 lines)
head –42 file	
ln 	Link files and directories	
lp 	Default line printer
lp –ddestnumber file	
ls 	List content of directories
ls –l 
ls –a
ls –R
ls –F
ls –d  dirname   (only list name of dirname)
ls –ld dirname(s)   long listing of dirname
ls dirname(s)    files inside the dir	
man 	On line manual
man cp	
mailx 	Interactive message processing system
mailx 
mailx –s “subject” abc@xyz.com < filename	
mesg 	Permit or deny messages to terminal
mesg   (to check the mesg is on or off)
mesg  y  (to allow message)
mesg n (not allow message)	
more 	Display file one screen at a time
more  file(s)	
mkdir 	Make a directory
mkdir dirname	
mv 	Move or rename files or directories
mv file filename
mv file file2 file2 dir
mv dir dir2	
nl 	Line numbering filter
nl file  (one file only)	
passwd 	Change login passwd
Passwd	
pg 	Display content of file one page at a time	
ps 	Process status
ps   (processes under your UID)
ps –ef  (all processes in the system)	
pwd 	Print working directory	
quota –v	Display disk usage and limit	
rm 	Remove files or directories
rm file(s)
rm –r dir	
rmdir 	Remove directories (must be empty)
rmdir dirname	
sort 	Sort or merge file	
tail  	Display last 10 line of a file
tail filename (last 10 line of file)
tail –38 file (last 38 lines of file)	
talk 	Talk to another users	
tee 	Output data to file and terminal
tee filename	
touch 	Update access, modification, and/or change time of file	
uncompress 	uncompress filename.Z	
umask 	Set or display the file mode creation mask	
uniq 	Report repeated lines in a file (file must be sorted)
uniq filename	
wc 	Count words, lines, characters in a file	
whereis 	Locate source of program
whereis pgm	
which 	Locate a program file from paths
which pgm1	
who 	Who is on the system	
who am I	What user id that I am logging on	
write 	Write message to another user 	
zcat 	Display content of a compressed file