Unix Why?
There are only two kind of people who understand 0 1 and who don’t understand.
Navigating The File System:
pwd: Checking your Current Directory
cd: Changing Directory
mkdir: Making Directories
rmdir: Removing Directories
ls: Listing Files
General-Purpose Utilities:
banner: Display a Blown-up Message
cal: The Calendar
date: Display the System Date
who: Login Details
tty: Knowing Your Terminal
man <command>: Displays help on <command>
apropos <keyword>: locates commands by keyword lookup
whatis <command>: Brief command description
Handling Files:
cat: Displaying and Creating Files
cp: Copying a File
rm: Deleting Files
mv: Renaming Files
more: Paging Output
lp: Printing a File
file: Know the file types
wc: Line and Word and character counting
split: Splitting a File into Multiple Files
cmp: Comparing two files
File Attributes:
ls –l: listing File Attributes
ls –d: Listing Directory Attributes
stat: Display File Permissions
chmod: Changing File Permissions
chown: Changing Ownership
chgrp: Changing Group
chsh: Changing Shell
ln: Links
umask: Define Defaults File Permissions for a User
The Environment:
env: Displays Environment Properties
.profile: The Script Executed During Login Time
PWD: Know your Current Directory
HISTSIZE: Define History Size
LOGNAME: Login Name
SHELL: Your Default Shell
HOME: Define Home Directory
PATH: Declare Path
MAIL: Declare Mail Directory Path
alias: Define short-hand names for commands
The Process:
ps: Process Status
<command> &: To run a process in Background
bg: To run a process in Background
fg: To run a process in Foreground
kill: Premature Termination of a Process
nice: job execution with low Priority
at and batch: Execute Later
cron: Running jobs Periodically
Communication And Electronic Mail:
write: Two-way Communication
mesg: Your Willingness to Talk
talk: Splits the screen into two windows for chatting
mail: The mailer
news: To read news messages
elm: A screen-oriented mail handler
pine: Another mail program
finger: Details of Users
Networking:
telnet: Remote Login
ftp: File Transfer (protocol)
rlogin: Remote Login Without Password
rcp: Remote File Copying
System Administration:
useradd: Adding Users
/etc/passwd: User Information
/etc/shadow: Encrypted Passwords
userdel: Removing Users
fsck: File System Checking
df: Checking disk size
du: Checking file size
groupadd: Adding Group
groupdel: Deleting Group
groupmod: Modifying Group
