Class Notes of CSCI 101 Introduction to Computers (Spring 2024)
===============================================================


Wednesday, January 24, 2024
---------------------------

   rwx rwx rwx
   --- --- ---
    S   G   O

r: read
w: write
x: execute
S: Self
G: Group
O: Others (the Web)

shell> chmod 755 test.html

    S   G   O
   --- --- ---
   rwx rwx rwx
   --- --- ---
   111 101 101 (1*2**2 + 0*2**1 + 1*2**0 = 5)
   --- --- ---
    7   5   5


Friday, January 19, 2024
------------------------

       1
       09
     + 03
     ----
       12 = 1 x 10 + 2

 4212 = 4 x 10**3 + 2 x 10**2 + 1 x 10**1 + 2 x 10**0


1 + 1 = 2 = 10 = 1 x 2 + 0 
1 + 0 = 1 =  1
0 + 1 = 1 =  1
0 + 0 = 0 =  0

           11010100

           0000011
 Step 1:   00101011  
 Step 2: + 00000001
 ------------------
 Step 3:   00101100 = 1 x 2**5 + 1 x 2**3 + 1 x 2**2 
                    = 32       + 8        + 4
 Step 4:            = 44


Wednesday, January 17, 2024
---------------------------

Slide 1.8
---------

a = 30
b = 18

gcd = 30 % 18 = 12
a = 18
b = 12
(18 % 12 = 6 != 0)

gcd = 18 % 12 = 6
a = 12
b = 6
(12 % 6 = 0 == 0)

print gcd = 6



Useful Linux commands:

d rwx r-x r-x
  --- --- ---
  me   g  3rd
  111 001 110
  --- --- ---
   7   1   6 

lynx -dump -source "http://undcemcs01.und.edu/~wen.chen.hu/course/101/exercise/2/figure/0321336577.jpg" > 0321336577.jpg

cd
emacs .profile
source .profile
mkdir public_html
mkdir public_html/cgi-bin
chcon -R -t httpd_user_content_t /home/first.lastname/public_html 
chmod 755 *
rm
rmdir