Question

This is done in Linux terminal. Modify the .bashrc file using command line which would add the following functionality to your shell upon opening a new terminal:

1. Alias called “fc” (short for “folder contents) invoking the command “ls -lah”B. Welcome message “This is demo number 7” C. Variable “semester” being equal to “Winter 2020” and print the value on screen

2. Create any directory of your choice and add it to PATH variable.

3. Show an example of local and environment variable

4. Create a small shell script to give value to a variable and display it three times and execute the script

5. Study the configuration file .bashrc Make changes to HISTFILESIZE environment variable and see what happens

6. When you change the PATH variable completely, show what happens and why?

Answer 1

Answer 1
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alias fc='ls -lah'
echo "This is demo number 7"
semester="Winter 2020"
echo $semester

Answer 2
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1. Open the .bashrc file in your home directory (for example, /home/your-user-name/.bashrc) in a text editor.
2. Add export PATH="your-dir:$PATH" to the last line of the file, where your-dir is the directory you want to add.
3. Save the .bashrc file.
4. Restart your terminal.

Answer 3
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madhav@siftworkstation:~$ test=madhav
madhav@siftworkstation:~$ echo $test
madhav
madhav@siftworkstation:~$

local variable is test and assigned values in it

environment variable

printenv is command with values like shown in above screenshot you can type

printenv USERNAME will print madhav or printenv USER will print madhav as well because in environment variable they are set.

Answer 4
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val1=1
val2=2
val3=3

for((i=0;i<3;i++))
do
   echo $val1
   echo $val2
   echo $val3
done

Answer 5
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HISTSIZE is the number of lines or commands that are stored in memory in a history list while your bash session is ongoing.

HISTFILESIZE is the number of lines or commands that (a) are allowed in the history file at startup time of a session, and (b) are stored in the history file at the end of your bash session for use in future sessions.

Answer 6
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if you change the path say /usr/local/bin to /usr/local/bin1 then no commands will be execute like cp , mv cat etc because they are all mapped in the bin folder

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