Basic Commands

More Information

You can refer to command --help or man command for more information about any command.

pwd

pwd command stands for print working directory. It displays the current directory you are in.


kc@kcserver:~$ pwd
/home/kc

echo

echo command used to display a line of text/string that is passed as an argument.


kc@kcserver:~$ echo "Hello World"
Hello World
 
kc@kcserver:~$ echo -n "Hello World" # without trailing newline
Hello Worldkc@kcserver:~$

uptime

uptime command shows how long the system has been running, along with the current time, number of users, and system load averages.


kc@kcserver:~$ uptime
 14:23:58 up 7 min,  2 users,  load average: 0.04, 0.03, 0.00

mkdir

mkdir command is used to create a new directory.


karchunt@kcserver:~$ mkdir folder1 folder2
karchunt@kcserver:~$ ls
folder1  folder2

You can create a folder using relative path as well, but the parent directories must exist. If the parent directory does not exist, you can use -p option to create the parent directories as needed.


karchunt@kcserver:~$ mkdir folder3/innerfolder
mkdir: cannot create directory ‘folder3/innerfolder’: No such file or directory
 
karchunt@kcserver:~$ mkdir -p folder3/innerfolder
karchunt@kcserver:~$ ls
folder3
karchunt@kcserver:~$ ls folder3
innerfolder

cd

Absolute vs Relative Paths

An absolute path starts from the root directory /, while a relative path is relative to the current working directory.

cd command stands for change directory. It is used to change the current working directory.

To move up one level in the directory hierarchy, you can use .. as an argument to cd.
```
karchunt@kcserver:~/folder3$ cd ..
karchunt@kcserver:~$
```
If you want to go back to your home directory, you can use cd without any arguments or use cd ~.
```
karchunt@kcserver:~/folder3$ cd
karchunt@kcserver:~$
```

Navigate to a specific path by providing the full or relative path as an argument to cd.


karchunt@kcserver:~$ cd folder3/innerfolder
karchunt@kcserver:~/folder3/innerfolder$

mv

mv command is used to move or rename files and directories.

To rename a file or directory, provide the current name and the new name as arguments.


karchunt@kcserver:~$ mv oldname.txt newname.txt
karchunt@kcserver:~$ ls
newname.txt

To move a file or directory to a different location, provide the source path and the destination path as arguments.
```
karchunt@kcserver:~$ mv newname.txt folder1/
karchunt@kcserver:~$ ls folder1
newname.txt
```

cp

cp command is used to copy files and directories.

To copy a file, provide the source file and the destination file or directory as arguments.


karchunt@kcserver:~$ cp folder1/newname.txt folder2/
karchunt@kcserver:~$ ls folder2
newname.txt

To copy a directory and its contents, use the -r (recursive) option.


karchunt@kcserver:~$ cp -r folder1/ folder3/
karchunt@kcserver:~$ ls folder3
newname.txt

rm

More Information

If you face some folders unable to delete due to permissions issues. You can use sudo rm -rf foldername/ to force delete the folder with superuser privileges. Be very careful while using sudo rm -rf as it can delete important system files if used incorrectly.

rm command is used to remove files and directories.

To remove a file, provide the file name as an argument.


karchunt@kcserver:~$ rm folder2/newname.txt
karchunt@kcserver:~$ ls folder2
karchunt@kcserver:~$

To remove a directory and its contents, use the -r (recursive) option.


karchunt@kcserver:~$ rm -r folder3/
karchunt@kcserver:~$ ls
folder1  folder2

cat

cat command can be used to view the contents of a file, create a new file, or concatenate multiple files.

To view the contents of a file, provide the file name as an argument.


karchunt@kcserver:~$ cat folder1/newname.txt
This is a sample text file.

To create a new file and add text to it, use the following command:


karchunt@DESKTOP-CCAQ09F:~$ cat > sample.txt
hello
HELLO
hi
karchunt@DESKTOP-CCAQ09F:~$ cat sample.txt
hello
HELLO
hi

After typing the text, press ENTER and CTRL + D to save and exit.

To concatenate multiple files and display their contents, provide the file names as arguments.
```
karchunt@kcserver:~$ cat file1.txt file2.txt
Content of file1
Content of file2
```

touch

touch command is used to create an empty file. To create an empty file, provide the file name as an argument.


karchunt@kcserver:~$ touch newfile.txt
karchunt@kcserver:~$ ls
newfile.txt

more command is used to view the contents of a file one screen at a time.

The key controls while using more are:

Press SPACE to go to the next page.
Press ENTER to go to the next line.
Press q to quit viewing.
Press b to go back one page.
Press / followed by a search term to search within the file.


karchunt@kcserver:~$ more largefile.txt
This is line 1
This is line 2

less

less command is similar to more, but it provides more advanced features for viewing file contents.

The key controls while using less are:

Press SPACE to go to the next page.
Press b to go back one page.
Press ENTER or Down Arrow to go to the next line.
Press Up Arrow to go to the previous line.
Press q to quit viewing.
Press / followed by a search term to search within the file.
etc


karchunt@kcserver:~$ less largefile.txt
This is line 1
This is line 2

ls

ls command is used to list the files and directories in the current directory or a specified directory.

To list files and directories in the current directory, simply use ls.
```
karchunt@kcserver:~$ ls
folder1  folder2  newfile.txt
```
To list files and directories in a specific directory, provide the directory name as an argument.
```
karchunt@kcserver:~$ ls folder1
newname.txt
```

You can use various options with ls to modify its behavior. Some common options include:

-l: Long listing format, which provides detailed information about each file and directory
-a: Show all files, including hidden files (those starting with a dot .)
-h: Human-readable file sizes (e.g., KB, MB)
-t: Sort by modification time, with the newest files first
-r: Reverse the order of the sort


karchunt@DESKTOP-CCAQ09F:~$ ls -lahtr
total 68K
drwxr-xr-x 3 root     root     4.0K Nov  1 17:37 ..
-rw-r--r-- 1 karchunt karchunt  807 Nov  1 17:37 .profile
-rw-r--r-- 1 karchunt karchunt 3.7K Nov  1 17:37 .bashrc
-rw-r--r-- 1 karchunt karchunt  220 Nov  1 17:37 .bash_logout
drwx------ 2 karchunt karchunt 4.0K Nov  1 17:38 .cache
drwxr-xr-x 2 karchunt karchunt 4.0K Nov  2 15:05 .landscape
drwx------ 3 karchunt karchunt 4.0K Jan 24 17:18 .config
-rw-rw-r-- 1 karchunt karchunt    0 Jan 25 10:44 .motd_shown
-rw-r--r-- 1 karchunt karchunt    0 Jan 25 11:24 .sudo_as_admin_successful
drwxr-xr-x 3 karchunt karchunt 4.0K Jan 25 14:59 folder3
drwxr-xr-x 3 karchunt karchunt 4.0K Jan 25 15:06 folder1
-rw-r--r-- 1 karchunt karchunt   15 Jan 25 15:11 sample.txt
-rw-r--r-- 1 karchunt karchunt    6 Jan 25 15:14 sample2.txt
drwxr-xr-x 3 karchunt karchunt 4.0K Jan 25 15:17 .local
-rw-r--r-- 1 karchunt karchunt 5.4K Jan 25 15:18 largefile.txt
-rw------- 1 karchunt karchunt  903 Jan 25 15:20 .bash_history
-rw------- 1 karchunt karchunt   38 Jan 25 15:23 .lesshst
drwxr-x--- 8 karchunt karchunt 4.0K Jan 25 15:23 .