Lab 3 CREATE .TXT FILES WITH TERMINAL

 

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1. To view .bashrc file, we can use command line "cat .bashrc"

        output : 

- The # symbol is used to comment in the terminal.

- The "export" command is used to create a variable in environment variable.

- The "alias" command is used to assign a long command line to a variable.

- The control statements are allowed in the terminal. Example like "if".

- If user wish to modify the .bashrc file , command line ". .bashrc" must used.

2. When we call out a file with blanks and special characters, we will get error like this :

* This show me trying to call out file 'blank file.txt', it prompt out no such file or directory.

space file.txt

-To solve this error, we add "" to the command line and like this :

- if we use Tab to auto fill a file with space, it will ouput symbol \ for space.

    press Tab :

special>.txt

- If we try to list special>.txt in terminal without "" or \ :

-dashstart.txt 

- If we try to list -dash.txt in terminal we will get error but if we add ./ to it :

3. We can use command line "echo $?" to return code when encounter error in terminal.

    example : 

- First we test ping at packt.com and we get '0' when using command "echo $?"

    *0 mean no error

- Then we test ping at phooey(which is unavailable) and we get '2' when using command "echo $?"

    *2 is the error code of last command

4. We can save the output of a command in terminal into a file by using ">" :

*The output of ifconfig is saved to file1.txt and used cat to display content of file1.txt.

-we can also use different direction "<" to input text file to the terminal command :

example: write content of file1.txt to sort in terminal

-we can use two direction "<" and ">" to insert file to use in terminal and save the output to another file :

-we can also send the output to another command using the pipe operator in the terminal. 

Example : Display only lines from route that only have eth0 using pipe operator

5. We can send the output of a terminal to another terminal. By using "tty" to determine the terminal current in and where to send, we can send to another terminal using "> /dev/pts/...".

Example : Sending output of route from a terminal to another terminal located at /dev/pts/1

Output: 

6. We can use program Screen to do many action using shortcut keys :

-start screen with "screen -L"

-Press ctrl + A , then press C . Do this 3 times to open 3 new bash window

-Then press ctrl + A, then 3 , twice to show that bash window 3 is exist.

-If want to show bash window 0 can press ctrl + c , then 0

- END OF LAB 3 -