Unix: Vi Editor Commands (CheatSheet)

 Opening and Exiting vi

• vi filename   ->   Open a file
• :q!   ->   Quit without saving
• +wq!   ->   Save and quit

Switching Modes

• esc   ->  exit to command mode
• i   ->   insert mode (insert before cursor)
• I   ->  insert at beginning of line
• a.  ->  append after cursor
• A  ->  append at end of line
• o   ->  open a new line below
• O  ->  open a new line above

Navigation

• h   ->  move left
• l    ->  move right
• j    ->  move down
• k   ->  move up
• 0   ->  move to beginning of line
• ^   ->  move to first non-blank character
• $   ->  move to end of line
• w  ->  jump to next word
• b   ->  jump to previous word
• gg ->  go to beggining of file
• G  ->  go to end of the file
• :n  ->  go to line number n

Editing and Deleting

•  x    ->   delete a character
•  dw  ->  delete word
•  dd   ->  delete entire line
•  D    ->  delete from cursor to end of the line
•  u     ->  undo last action
•  r     ->  replace single character
•  yy   ->  copy entire line where the cursor is currently located
•  p     ->  paste after cursor
•  P     ->  paste before cursor

Search and Replace

• /text  ->  search forward for text
• ?text  ->  search backward for text
•   n    ->  repeat search word forward
•   N   ->  repeat search word backwards
•  :%s/old/new/g  ->  replace all occurrences of old with new
• :set nu  ->  show line numbers

Grade 6 : Algebra - Expression - Example problem

1) Which expression represents 5 more than the product of 2 and  y ?

Solution

Product of 2 and y is  2*y or 2y

 5 more than the product of 2y is 2y + 5 or 5 + 2y

---------------------------------------------------------------------------------------

2) Which value of b makes the inequality 3b > 12 true?

a) 2           b)3          c)4          d)5

Solution

Lets assume b=2

Replace b by 2 in 3b > 12

                          3*2 > 12

                           6 > 12 ( which is not true because 6 < 12)

Lets assume b=3

Replace b by 3 in 3b > 12

                          3*3 > 12

                           9 > 12 ( which is not true because 9 < 12)

Lets assume b=4

Replace b by 4 in 3b > 12

                          3*4 > 12

                           12 > 12 ( which is not true because 12 = 12)

Lets assume b=5

Replace b by 5 in 3b > 12

                          3*5 > 12

                           15 > 12 (yes, 15 is greater than 12 which is true)

Answer is d) 5

Grade 7 - Math - Algebra Word problem

The cost of renting a movie is $1.59 for the first two days $0.50 for every day after two days. If Rosy rented a movie and kept it for a week, how much money will she have to pay?

Solution

No.of days Rosy kept the rented movie = 7days (a week)

Cost for the first two days = $1.59
Cost for the remaining 5days = 5*$0.50 

                                           = $2.50

Total amount Rosy has to pay for the rented movie = $1.59 + $2.50 
                                                                          = $4.09

RHCSA Exam Notes : Hard and Soft link in Unix/Linux

 Create Hard links:

Command:

The below command created hardlink called file1.txt for the existing file trial1.txt in /home/student

ln file1.txt /home/student/trial1.txt

Create Soft link:

Command:

The below command created soft link called file1.txt for the existing file trial1.txt in /home/student

ln -s file1.txt /home/student/trial1.txt

Red Hat Certified System Administrator(RHCSA) Exam - Key points(Notes)

 list command in unix : ls

ls

It will show the full list or content of your directory

 

ls -a

In Linux/Unix, hidden files start with . (dot) symbol and they are not visible in the regular directory. The (ls -a) command will enlist the whole list of the current directory including the hidden files.

 

 ls -l

It will show the list in a long list format. 

 

Column 1 : indicates information regarding file permission.
Column 2 : indicates the number of links to the file.
Column 3 & 4 : indicates the owner and group information.
Column 5 : indicates the file size in bytes.
Column 6 : shows the date and time on which the file was recently modified.
Column 7 : shows the file or directory name.

 

ls ~

ls ~ command shows the contents of the home directory

 

 

ls -g

If we don't want to display the owner information in your list, then we can exclude this column with the help of this command. 

 

 

ls -lrt

The ls command is used for listing the contents of a directory. The lrt part is a combination of three different options:

• l: This is for the long listing of the contents. It shows one file in each line with additional info such as permissions, ownership, size, timestamps etc.
• t: This one sorts the long listing output based on time.
• r: This one reverses the order of ls command output.

 

 

 

ls -n

It is used to print group ID and owner ID instead of their names.

 

 

 ls -li

This command prints the index number if file is in the first column.

 

 

 ls -p

It is used to identify the directory easily by marking the directories with a slash (/) line sign.

 

 

ls --version

It checks the version of ls command.