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About the Instructor...
Nghiep Nguyen, MSEE-Sacramento High School, 1983- AA in Math and Science
Sacramento City College, 1985-BS in Electrical Electronics Engineering
UC Davis, 1987
-MS in Electrical Electronics Engineering
CSUS, 1993
Experience
- Electronic Engineer, 87 - 90
Sacramento Army Depot
Write Test Program Sets for Unit Under Test for Tomahawk Computer.
- Software Engineer, 90 - 95
McClellan Air Force Base
Operational Flight Program for A-10
Experience
- Electronic Engineer, 95 -96
Tinker Air Force Base
B-2 Stealth Bomber
- Software Engineer, 96 - 98
McClellan Air Force Base
A-10 aircraft
Experience
- Associate Programmer 1/98 - 10/98
P.O.S.T: Work with PowerBuilder, SQL
- Associate Systems Software: 10 - 11/98
F.T.B: Sybase DBA
- Systems Software Specialist, 11/98 to Present
Legislative Data Center
Unix (Sun Solaris) System Administrator
Experience
Adjunct Faculty: 8/97 to Present
Cosumnes River College
Unix, Internet, HTML
Java, Visual Basic Visitor Lecturer: 8/02 – 6/03
California State University, Sacramento
Visual Basic, Java
Office Hours
None E-mail: nghiep_nguyen@yahoo.com Work: nghiep.nguyen@lc.ca.gov Web site: http://
www.geocities.com/nghiep_nguyen
Textbook(s)
Required– UNIX System V - A Practical Guide (Third
Edition)• by Mark G. Sobell• Addison-Wesley Publishing Company
Strongly recommended– CIS 14A Lecture Slides
• By Markus Geissler• Download from website
Reverse Flows of Knowledge
Examinations– Hands-on in Classroom – One make-up exam per person at the
instructor’s convenience • No more than 90% possible on makeup exams
Homework projects
Things You Should Know Before Starting This Course A basic understanding of the
components of a computer system– CIS 1
UNIX
What exactly is UNIX?– Computer Operating System– large set of utility programs
• general user• programmer• communication• administrative commands
Operating System
Definition:An operating system (OS) is a set of instructions that manages all computer operations and provides an interface between user(s) and system resources.
UNIX
Computer operating system (OS)– Large set of utility programs– Based on C programming language– Used in enterprise networks
OperatingSystem
OperatingSystem
Disk DriveDisk Drive
MonitorMonitor
KeyboardKeyboard
MouseMouse
PrinterPrinter
ApplicationApplication
What Can UNIX Do For You?
General user applications Programming environment Typesetting tasks Communication applications Administration commands
Central Processing Unit (CPU)
“Brain” of the computer– Executes instructions from programs and
processes– Manufacturers include
• Intel• Advanced Micro Devices (AMD)• Cyrix• Motorola• Sun Microsystems
Memory
RAM (Random Access Memory)– Volatile
• Information disappears when electrical power to RAM is interrupted
• Capacity measured in Megabytes (MB)• Access speed measured in Nanoseconds (ns)
– Holds data before and after CPU processes them
• Program instructions• Application data
Storage
Hard disk– Installed inside computer’s case
Floppy/ZIP®/JAZ®/SyQuest® disks– Portable; require disk drive
Disks are typically non-volatile– Data called into memory when needed
• Capacity measured in Gigabytes (GB)
Magnetic Tape– Largely used for data backup
Input/Output (I/O)
Reads input from a device into memory– Keyboard– Mouse
Writes output from memory to devices– Monitor– Printer
Disk drives are input and output devices– long term storage devices
UNIX Facts
Created in 1969– by Kent Thompson
Based on C language AT&T (Bell Labs) shared UNIX with colleges
and universities– Colleges made enhancements– Berkeley Software Distribution (BSD)
See Introduction to UNIX– by Fiamingo, DeBula and Condron
Linux
Compact version of UNIX for PC– Created by Linus Thorvald
Not yet standardized– Supported by a large, active user
community Free versions available on the Internet
– approx. $50 for RedHat Linux
Major UNIX Components
Kernel Shell File System
KernelKernel
Shell & UtilitiesShell & Utilities
HardwareHardware
Kernel
Core of UNIX OS– Manages hardware, memory and file
system resources– Controls transmission of information
between user application and CPU– Stores information about the arrangement
of the computer system and the network
Shell
Interface between user and OS Korn shell
– Most robust features Bourne shell
– Subset of Korn shell C shell
– Not related to other two shells– Most widely used in SunOS
UNIX OS Components
Shell– Shell program are interpreted, not compiled
• commands are read and executed one by one• compiled program is read and converted to a
machine language then execute all at once• slower than compiled language such as C
Three types of Shells: Korn, Bourne, and C
Shell History
Bourn -- Steve Bourne at AT&T Bell Labs– Original UNIX shell -- compactness & speed– lack features for interactive use
C -- Bill Joy (SUNW)– friendly features for users– larger and slower than Bourne
Korn -- David Korn of AT&T Bell Labs– faster than C shell, will run Bourne Script
File System
Organizes data on disk in a hierarchical structure of directories
File– Program or data
Directory/folder– Similar to file drawer
• Each disk has root directory
Subdirectory– Directory/folder within other directory
File System Structure
Root (/)– /etc : system administration files– /usr : executable commands, s.a. utilities– /opt : third-party software– /export/home or /home : user’s home
directory
Multitasking OS
Used to approach 100% of computer resource utilization while increase user productivity– Reduced cost per user
• Time slicing
– Users can run multiple processes• Increases user productivity
UNIX refers to task as “process”– Usually maximum of 25 concurrent processes per
user session
Multi-User OS
Supports 1 - 2000 users– Users share system resources
To approach 100 percent in computer resource utilization while reducing the cost per user
Share system resources
Interactive Mode
Immediate response to keyboard or mouse input
“No news is good news”– Display returns shell prompt after
commands are issued• Different shells have different prompts
– Detailed feedback only when errors made
Networking Terms
Host - a computer system Host Name - a unique name for a system IP address - a number used by networking Network
– connects machines to enable comm. between users on other systems.
Server provides resources to one or more clients on the network
More Terms
Client is a machine that uses services from one or more servers on a network
NFS (Network File System) enables files to be shared across the network.
NIS (Network Information Services) enables system administration functions to be centralized on a server.
Client-Server
Network
Connects computers to enable communication between users on multiple systems
Clients vs. Servers
Server– Provides resources to one or more clients on
the network– Usually requires more powerful equipment than
clients Client
– Computer that uses services from one or more servers
Front end vs. back end
Set Up
User Account– must have it set up before a user can log in– contains essential user account info
• User name identifies a user to the system
– is created by System Administrator. Bring your class registration/schedule to
the computer lab. The lab assistant will set up the Unix account for you
Logging into CRC’s LAN
Login name– First four letters of your last name– Last four digits of student ID number
Initial password: new2lan– Change password right away
Password Security
Do not choose a password that can be related to you!
Use a password that does not resemble a word in the dictionary– Case sensitivity
Password Guidelines
No less than six characters Must contain at least two alphabetic
characters and at one numeric or special character– can have spaces, avoid special characters
Cannot be login name or reverse New password must differ from old
password by at least three characters
Accessing CRC’s UNIX Box
From Windows 95 or Windows NT– Connect to Internet via your ISP– Start, Run…– TELNET 165.196.137.125
orTELNET cosumn.crc.losrios.cc.ca.us
User Account
Required for user login Identifies user to the system Contains essential user account info
– Special environment settings for user– Mail file
Logging into CRC’s UNIX Box
Log into system– Initial username is same as for CRC’s LAN– Initial password: new2mini– Password will not display when typed– Connection times out if you take too long
Use exit command at the $ prompt to log out– Also possible to disconnect within TELNET
application
Entering UNIX Commands
Type commands with keyboard To correct a typing error, use Delete
key– NOT the Backspace key
Press Enter key to send command to kernel
Changing Your Password
Use passwd command at $ prompt to change your password– Type old password first– Type new password twice
• Password will not be displayed when typed• Password has to have at least one number in it• Suggestion: Use same password as LAN
account and add a number, if necessary
Getting Help in UNIX
Use man command Include command about which you want
help– man ls– Use man ls | more to display one page at a
time• “Pipe” character
– Use Ctrl-C to interrupt file display• If file is too long for one screen
Logging a TELNET Session
Record all activity within a session In TELNET utility
– Choose Terminal, Start Logging…• Specify filename to which to log
– Local drive– Network drive (U: drive in CRC lab)
» Up to 5 MB of space
– Choose Terminal, Stop Logging to stop writing to log file
The script Command
Logs commands entered and results displayed– If no filename specified, script logs to file
typescript Type exit to stop logging and close the
log file
Printing Log Files
Type lp filename to print to CRC lab FTP file to home computer and print to
local printer– Printing from DOS Editor may be easier
than from Notepad• Potential problems with line breaks• Turn off Word Wrap
UNIX Commands
Command line format– command [ - option(s) argument(s)]
Options modify the command Arguments tell the computer to what to
apply the command Example
– cd [directory_name]– ls [aFIR] [pathname]
Command Syntax
Command Line Format– command [option(s)] [argument(s)]– case sensitive– blank space does matter since it is the
delimiter for the shell– do not necessary require all three parts– 256 characters can be entered on a single
command line
Commands
pwd -- present working directory cd -- change directory mkdir -- create a new directory ls -- diplays contents of your directory
– l -- stands for long information– F -- File type option– a -- display all files (including customization files)– R -- display recursively all directories/sub-
directories and their corresponding files
Commands
ls -F will display the following symbols next the listing of files:
/ for directory
* executable file, shell script
@ symbolic link
nonetext file (ASCII)
Commands
rmdir - remove directory head -n --- displays the first n lines tail -n -- displays the last n lines wc -- word count command to display
numbers of lines, words, characters diff -- to display the differences between
two files.
The cal Command
Displays a calendar on the screen Syntax: cal [ [month] year]
– Month from 1-12
– Year from 1 to 9999 (!) Example: cal 1999
– Displays the calendar for 1999
– Eastern and Western calendars were combined in 1752
• Check out September 1752!
The who Command
Lists current system users– Syntax: who– Example: who | sort -r
• Sorts users in reverse order
– Example: who | grep geisslm• Allows you to check whether or not user
geisslm is logged-in
– More details on examples later
Path
Absolute path– Type pwd at $ prompt
• Present working directory• /usr/cis14a/user B/home
– To change to directory, typecd /usr/cis14a/user B/home
Relative path– From /usr/cis14a/user B directory, type
cd home
File Path
absolute path -- Starts with / (stands for root directory) and go to where you want to go
relative path -- start from where you are and move to sub-directory or parent directory
The cd Command
Navigate directory structure Type cd .. at $ prompt to change to
parent directory– Directory above current directory
Type cd without attributes to change to home directory
Special Directory Names
. represents current directory .. represents parent directory
– “Above” current directory in directory tree Combine .. and “sibling” subdirectory
name to move to “sibling” subdirectory– To change from /usr/cis14a/user B
directory to /usr/cis14a/user A, typecd ../user A
The ls Command
List the contents of current directory Type ls at $ prompt Directory entry types
– - (hyphen) for file– d for directory
ls Command Options
Directory entry type User/group/other (world) permissions Number of links Owner name Owner group File size in bytes/blocks Date of file creation/last access Filename/directory name
ls Command Options
ls -l lists details about contents– Long version
ls -F shows slash (/) after directory name listing
ls -R lists contents of entire tree (including subdirectories)– Recursive
More ls Command Options
ls -r lists contents in reverse order ls -l (filenames) to list specific files ls -a displays all contents, including
hidden ls -s lists size of file/directory in blocks
– 1 block = 512 bytes ls -i displays system’s item number for
each directory entry
Combining ls Command Options
Possible to combine ls command options– ls -a -F is the same as– ls -aF
| more option– Say “pipe more”– Lists one screen at a time
• Example: ls -R |more
• More on “piping” later
UNIX Filenames
At least one character long– Maximum length: 255 characters
Case-sensitive!– Uppercase and lowercase characters are
distinct• Unlike DOS or Windows 9x
Special Characters in UNIX
Filenames cannot contain certain “special characters”– Special meaning to the shell
Examples– & ; | * ? ‘ “ ` [ ] ( ) $ < > { } ^ # / \– see p. 38 in Sobell textbook for list
UNIX Wildcards
Wildcards replace characters– * replaces zero, one or more characters– ? replaces one character– [ ] match one of the choices inside brackets– { } match each of the choices inside braces
Example: ls ?h*e– Returns ah123e, bhe, 1h23e, etc.
Example: ls t[aeiou1-3]p– Returns tap, tep, tip, top, tup, t1p, t2p, t3p
Creating a Directory
Type mkdir command at $ prompt– Example: mkdir reports
Possible to create multiple directories with one command– Use space as delimiter– Example: mkdir memos letters
Clearing the Screen
Use clear or cls command to clear screen– Clears screen buffer– $ prompt only will appear at top of screen
More mkdir Command Options
mkdir -p cis14a/hw1– Creates cis14a directory as well as hw1
subdirectory below cis14a directory Use -p option to create multiple
subdirectories at multiple levels at the same time– Example: mkdir -p cis14a/hw2 cis14b
The rmdir and rm Commands
Use rmdir to remove a directory– Current directory must be parent of directory
to be deleted unless absolute or other relative path is specified
If directory is not empty, use rm command– rm -r hw1 for recursive remove– rm -ir hw1 for interactive recursive remove
• System will prompt for confirmation
The cat and more Commands
cat [filename]– Displays contents of file
more [filename]– Displays contents of file in segments– Press Enter key to display one line at a time– Press Spacebar to display one screen at a
time Similar to pg [filename]
Ctrl Commands
Ctrl-c interrupts current activity Ctrl-u erases current command line Ctrl-w erases word in current command
line Ctrl-s stops scrolling screen output Ctrl-q restarts scrolling screen output Other commands can be customized for
user by administrator
The head and tail Commands
head [-n] filename– Displays top portion of file– head -5 hw1 displays first 5 lines of file
hw1 tail [-n] filename
– Displays bottom portion of file– tail -10 mbox displays last 10 lines of file
mbox
UNIX Editors
Use editor to create and edit files Several editors available
– vi - most commonly used– pico - not included in SVR4
• Not available at CRC
– emacs - not included in SVR4• Not available at CRC
Visual Editor (vi)
Type vi at $ prompt to start editor– vi [filename] to edit existing file (p. 212)
Three modes (p. 183)– Command mode
• Hit Esc key to access command mode
– Input (Text) mode– Last-line mode ([shift]&[colon] keys)
Accessing vi’s Insert Mode
From command prompt, press– i to insert text before cursor– I to insert text at beginning of line– a to append text after cursor– A to append text at end of line– o to open new line below cursor– O to open new line above cursor
• Page 214
Accessing vi’s Last-Line Mode
From command mode, press : (colon)– Necessary to save file and exit vi
vi Cursor Movements
Command mode– j or moves cursor down one line– k or moves cursor up one line– l or moves cursor to the right– h or moves cursor to the left– Ctrl-D moves down one half screen– Ctrl-U moves up one half screen– Ctrl-F moves forward one screen– Ctrl-B moves backward one screen
More vi Cursor Movements
Command mode– w moves to next word– $ moves to end of line– G moves to last line– Many more...
vi Commands
dd - delete one line to buffer ndd - delete n lines x - delete one character dw - delete one word to buffer d$ - delete to end of line to buffer d0 - delete to beginning of line to buffer
Command Mode
u -- undo a last command/change . -- do last change again Copy Text yy - yank a copy of a line to buffer nyy - yank a copy of n line to buffer yw - yank a copy of a word to buffer Past Text p -- put buffer after a cursor P -- put buffer before a cursor
Command Mode
cw -- change a word ncw -- change n words c$ -- change to end of a line r -- replace one character R -- replace the text (type over)
Last-Line Mode Commands
set showmode indicates Insert Mode or Command Mode– At bottom right of screen
set nu displays line numbers set nonu turns off line number display set list displays invisible characters set ic specifies that pattern search
should ignore case
Searching File Contents
Access vi’s command mode /[string] finds next occurrence of string
– /^[string] searches for string at the beginning of a line
– /\>[string] searches for string at end of word
• More examples on p. 197 of textbook
Last - line Mode
To turn off an option, put a “no” infront of the variable, i.e.,
set nu set nonu -- to turn it off Search for text /text -- go forward to the first occurence of text ?text -- go backward to previous occurence of
test
Moving and Deleting Lines
:3,8d deletes lines 3 to 8 :4,9m 12 moves lines 4-9 to line 12 :2,5t 13 copies lines 2-5 to line 13 :5,9w filename writes lines 5-9 to
filename
The cp Command
Create an exact copy of another file– With the same name in a different directory
• Possible to specify target directory only
– With a different name in the same directory Syntax: cp [source] … [target]
– Example: cp misc ./w1/misc• Copies file misc to subfolder w1 with the same
name
More About the cp Command
Example: cp w2/* w4– Copies all files from w2 directory to w4
directory– Does NOT copy subdirectories under w2
cp -r w2/* w4 also copies subdirectories– Recursive– Lowercase “R”!
Copying Multiple Files
Example: cp test test.out w3– Copies files test and test.out to w3
directory• w3 directory must exist
The mv Command
Moves and/or renames a file– Original file will disappear
• Different from cp command
Example: mv test exam– Renames file test to file exam
Example: mv exam w4– Moves file exam to directory w4
• w4 directory must exist
• mv command will not create it
Commands For Analyzing And Manipulating Files sort - sort file contents grep - search file for a pattern diff - point out differences between files comm - details file differences wc - counts words, lines and letters in file compress - reduce file size to conserve
disk space
The sort Command
Sort information within files and/or merge different files
Example: sort [filename]– Sorts [filename] alphabetically by first word
Example: sort -f +2 [filename]– Sorts [filename] alphabetically by third
word while ignoring case-sensitivity
The grep Command
Global regular expression pattern Find text patterns in files Syntax: grep [options] pattern [filelist] Example: grep echo test1
– Finds pattern echo in file test1 and displays lines matching pattern
More grep Command Examples
Example: grep -c echo test1– Displays line count of lines matching
pattern Example: grep -l echo
– Displays name of file that contains one or more matches
The diff Command
Shows lines that are different between two files
Syntax: diff [filename1] [filename2] Example: diff t1 t2
– Lists line and column number– Lists different text patterns
The comm Command
Displays line-by-line comparison of sorted files– Files must be sorted!
Syntax: comm [filename] [filename] … Example: comm file1 file2
– Results displayed in three columns• file1 unique text patterns
• file2 unique text patterns
• common text patterns
The wc Command
“Word Count” Display number of
– Lines– Words– Characters
Syntax: wc [options] [file-list] Example: wc -lw memo
– Displays the number of lines and words contained in the file memo
The compress Command
Compresses files to reduce amount of space required on disk– Similar to ZIP utility in DOS/Windows– Compressed file cannot be viewed/executed until
decompressed Syntax: compress [filename]
– Results in file filename.Z Example: compress -v text
– -v option displays compression ratio
Limiting Access to Resources
Use permissions– Not available in DOS
• Usually available only on network operating systems (NOS)
Who can change permissions?– Owner of file or directory– Administrator
Cis-14A: Misc
Printing – lp (after using script command)– File Transfer Protocol (FTP)
• Open Dos Command window• ftp 165.196.137.125 to log in
– Telnet Preference menu• Name your file, and location• start logging, do work, and stop logging• Use word processor to print your file
Cis-14A: Misc
Turn in assignments 1 and 2 File Structure
– Tree structure– Directory, and Files– File names
• Extension
– Absolute and Relative Path– cd, mkdir, rmdir, rm, cp, mv
Midterm 1
File Structure
Pyramid structure, inverted tree Each directory -- a subject
– a folder– can be divided into smaller directories for
more clarity or easy to use– sub-directory(ies) and/or file(s)– the end of a path
File Structure
File Name– 14 chars, some has up to 255 chars– A-Z, a-z– 0 - 9– underscore (_)– period (.)– comma(,)
File Structure
Filename Extension– usually after period (filename.ext)– can use more than one period– meaningful
• .ext, .c, .txt, .990206
– Invisible Filename• start with a period (.filename)• ls -a
File Structure
Absolute and Relative Paths Commands that work with directory
– Change or go– create, delete– rename– copy– empty, or non-empty
File Structure
Standard Unix Directories : / -- root– /home, /export/home– /usr -- system information
• /usr/bin• /usr/sbin
– /etc– /var -- files that vary as system runs– /tmp– /dev
File Structure
File or Directory Permission– r read from the file– w write to the file– x execute the file
ls -l
File Structure
chmod mode filename– mode
• who• op• permission
File owner or root can change permission of a file
File Structure
Links– ln -- link command – ln associate_file destination– hard link– soft link– ls -i
Redirection
Standard Input Standard Output Redirect Output
– cat > test– cntl-d to end
Redirect Input– command [arg] < filename
Filter
Processes an input stream of data to produce an output stream of data– who | sort | lp– who | tee test | grep user
UNIX/NFS Permissions
NFS file permissions– Read (r)– Write (w)– Execute (x)
Permissions listed in sequence of– User– Group– World (all other users on system)
File Permissions vs. Directory Permissions
Permission File Directory
Read r display/ list contentcopy
Write w modify files add/delete
Execute x execute control directory
access
Default Permissions
Default permissions after creation
rw-r--r--rw-r--r--File:
rwxr-xr-xrwxr-xr-xDirectory:
The chmod Command
Change permissions– Syntax: chmod opcode filename
Example: chmod u+w test– Gives you permission to write to file test– Does not influence existing permissions
Example: chmod g+r test– Gives your group permission to read file test– Does not influence existing permissions
Taking Permissions Away
chmod g-x– Takes execute permission away from
group– Does not change r and w permissions
Absolute Permissions
chmod o=x– Assigns execute permission to others
Example: chmod a=x test– Sets permissions to execute ONLY– r and w permissions are eliminated
Setting Permissions Using Symbolic vs. Numeric Mode Symbolic mode
– rwx rwx rwx– Example: chmod u+r test
Numeric mode– 421 421 421– Example: chmod 700 text
• Possible to set absolute permissions only
Redirecting Screen Output
Prevent output from echoing to screen– Is sent to file/printer instead– Example: ls > test.out
• Sends ls listing to file test.out
Caution: Existing file will be overwritten without warning!– Use >> option to append existing file– Example: ls >> test.out
Capturing Keystrokes
Record keystrokes– Use cat command– Syntax: cat > filename
• Type text to capture to file• Press Ctrl-D to stop capturing and write to
specified file
– Example: cat > test.out
Piping
Use the | (pipe) character– Modifies or redirects previous command in line– Example: man ls | more
• Displays help for the ls command one screenful at a time
– Example: who | sort | lp• Sends a sorted list of currently logged-in users to the
printer• Note: lp command must be last command
The write Command
Send instant message to other user on UNIX system– Similar to “chatting”– Recipient must permit messaging
• Type mesg y at $ prompt
– Example: write geisslm• Opens write session with user geisslm
• End conversation with “oo” (over and out)
• Press Ctrl-C to end transmission
The talk Command
Similar to write command– Divides user screen into two windows– Statements displayed in opposite window
on other end of communication
My “talking” appears here
Your “talking” appears here
The mailx Command
Send electronic mail from UNIX system– Syntax: mailx [username]
• Type subject line• Type message• Press Ctrl-D to send message
– Example: mailx geisslm• Type subject line and message
– Example: mailx geisslm < message.fil• Sends file message.fil to user geisslm
Using mailx Interactively
Many options available– Type ? at ? prompt to view list of available
options– Example: t 2
• Types second message on screen
– Example: delete 3 (or d 3)• Deletes message number 3 from message list
– Example: h• Displays list of message headers
Mail Message Listing
Message type– N - new message– R - read message– O - old message
Sender Date and time Size Subject
Changing Message Options
Possible to change options while typing message text– Use ~ (tilde) character options
• Be sure to specify option after issuing command• Otherwise information may be missing
Specify in mailx command line– mailx -s “E-mail test” geisslm < test.doc
• Sends file test.doc to user geisslm with subject “E-mail test”
More About mailx
Replying– r replies to all recipients of original
message– R replies to sender of message ONLY
Aliasing
Alias– For one username– For multiple usernames
• Distribution list
– Example: alias entry in .mailrc file• .mailrc is UNIX customization file• Entry: alias users user1 user2
– Mail sent to alias users is forwarded to user1 and user2
– Create current-session alias at $ prompt
Alias Advantages
Issue multiple commands through one alias– Example: alias home=‘clear;cd;pwd;ls’
• Clears the screen, changes to home directory, displays current directory and its contents
“Rename” UNIX commands to DOS commands– Example: alias dir=‘ls -l’
• Possible to issue DOS-like dir command to view contents of current directory
Removing Aliases
Use unalias command to remove alias(es)– Example: unalias test
• Removes test alias in current session
Recommended