Day 3 Task: Basic Linux Commands
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So our day 3 Task is .
Basic Linux Commands:
Task: What is the Linux command to
1. To view what's written in a file.
The file name is hello.txt
To view the contents of the file hello.txt, you can use the following command:
cat hello.txt
This will display the contents of the file hello.txt in the terminal. If the file is too large to fit on one screen, you can use the more or less command to view it one screenful at a time. For example:
cat helllo.txt | more
This will display the contents of the hello.txt file one page at a time, with instructions for navigating through the file. To exit from more, press q.
2. To change the access permissions of files.
To change the access permissions of the file hello.txt, you can use the chmod command in the following format:
chmod [options] mode hello.txt
Replace mode with the permissions you want to set on the file. Here are some examples:
- To give read, write, and execute permissions to the owner, and no permissions to anyone else, you can use the following command:
chmod 700 hello.txt
- To give read and write permissions to the owner and group, and no permissions to anyone else, you can use the following command:
chmod 660 hello.txt
- To give read and write permissions to the owner, and read-only permissions to the group and others, you can use the following command:
chmod 644 hello.txt
You can also use the chmod command with options to modify permissions recursively, for directories and their contents, and to specify permissions for different users and groups.
3. To check which commands you have run till now.
The Linux command to check the list of commands that you have run in the current session is history.
You can use it as follows:
history
This will display a list of the most recent commands you have executed in the terminal session, along with a line number. The commands are listed in reverse chronological order, with the most recent commands at the end of the list.
4. To remove a directory/ Folder.
The rmdir command can only be used to remove empty directories. If you want to remove a directory and all its contents, you can use the rm command with the -r (recursive) option. Here's how you can use the rmdir command to remove an empty directory:
rmdir DevopsChallange
This command will only remove the directory if it is empty. If the directory contains any files or subdirectories, the command will fail. If you want to remove a non-empty directory and all its contents, you can use the following command:
rm -r fDevopsChallange
This command will remove the directory and all its contents, including any files and subdirectories within it. Be careful when using the rm command with the -r option, as it will permanently delete the files and directories without moving them to the Trash or Recycle Bin. Always double-check the directory name before executing this command to avoid accidentally deleting important data.
5. To create a fruits.txt file and to view the content.
Linux commands to create a "fruits.txt" file and view its contents:
To create an empty "fruits.txt" file using the touch command:
touch fruits.txt
To add some content to the "fruits.txt" file using the echo command:
echo -e "Apple\nMango\nBanana\nCherry\nKiwi\nOrange\nGuava" > fruits.txt
This command will write the fruit names to the file, separated by newlines (\n). The -e option enables the interpretation of escape sequences like \n.
To view the contents of the "fruits.txt" file using the cat command:
cat fruits.txt
This command will display the contents of the file in the terminal. The fruit names should be listed on separate lines.
6. Add content in devops.txt (One in each line) - Apple, Mango, Banana, Cherry, Kiwi, Orange, Guava.
you can use the following commands:
echo "Apple" > devops.txt
echo "Mango" >> devops.txt
echo "Banana" >> devops.txt
echo "Cherry" >> devops.txt
echo "Kiwi" >> devops.txt
echo "Orange" >> devops.txt
echo "Guava" >> devops.txt
The first command creates a new file called devops.txt and writes the string "Apple" to it. The \> symbol is used to redirect the output of the echo command to the file devops.txt. The second to seventh commands append the strings "Mango", "Banana", "Cherry", "Kiwi", "Orange", and "Guava" to the end of the file devops.txt, respectively. The \>> symbol is used to append the output of the echo command to the end of the file.
Now, if you run the cat command to display the contents of the devops.txt file, you will see:
Apple
Mango
Banana
Cherry
Kiwi
Orange
Guava
This is the list of fruits written to the devops.txt file, with each fruit on a new line.
7. To Show only top three fruits from the file.
To show only the top three fruits from the devops.txt file, you can use the head command with the -n option. Here's how you can do it:
head -n 3 devops.txt
This command will display the first three lines of the devops.txt file, which correspond to the top three fruits in the list. The output should be:
Apple
Mango
Banana
These are the top three fruits in the devops.txt file.
8. To Show only bottom three fruits from the file.
To show only the bottom three fruits from the devops.txt file, you can use the tail command with the -n option. Here's how you can do it:
tail -n 3 devops.txt
This command will display the last three lines of the devops.txt file, which correspond to the bottom three fruits in the list. The output should be:
Kiwi
Orange
Guava
These are the bottom three fruits in the devops.txt file.
9. To create another file Colors.txt and to view the content.
To create a new file called Colors.txt and view its contents, you can use the following commands:
touch Colors.txt
cat Colors.txt
The touch command creates a new empty file called Colors.txt. The cat command is used to display the contents of the Colors.txt file, which should be empty at this point.
10. Add content in Colors.txt (One in each line) - Red, Pink, White, Black, Blue, Orange, Purple, Grey.
To add the colors "Red", "Pink", "White", "Black", "Blue", "Orange", "Purple", and "Grey" to the Colors.txt file, you can use the following commands:
echo "Red" > Colors.txt echo "Pink" >> Colors.txt echo "White" >> Colors.txt echo "Black" >> Colors.txt echo "Blue" >> Colors.txt echo "Orange" >> Colors.txt echo "Purple" >> Colors.txt echo "Grey" >> Colors.txt
The first command writes the string "Red" to the Colors.txt file. The \> symbol is used to redirect the output of the echo command to the file Colors.txt. The second to eighth commands append the strings "Pink", "White", "Black", "Blue", "Orange", "Purple", and "Grey" to the end of the file Colors.txt, respectively. The \>> symbol is used to append the output of the echo command to the end of the file.
If you run the cat command again to display the contents of the Colors.txt file, you will see:
Red
Pink
White
Black
Blue
Orange
Purple
Grey
This is the list of colors written to the Colors.txt file, with each color on a new line.
11. To find the difference between fruits.txt and Colors.txt file.
To find the difference between the fruits.txt and Colors.txt files, you can use the diff command. Here's how you can do it:
diff fruits.txt Colors.txt
This command will display the differences between the two files, if any. If there are no differences, the command will not produce any output.
If there are differences between the two files, the output will show the lines that are different between the two files. The output will look something like this:
1c
< Apple
---
> Red
3c3
< Banana
---
> White
5c5
< Orange
---
> Purple
6a7
> Grey
1
This output indicates that the first line in fruits.txt ("Apple") is different from the first line in Colors.txt ("Red"), the third line in fruits.txt ("Banana") is different from the third line in Colors.txt ("White"), the fifth line in fruits.txt ("Orange") is different from the fifth line in Colors.txt ("Purple"), and the Colors.txt file has an additional line ("Grey") that is not present in the fruits.txt file.
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Happy Learing..