You can use command --help or man command for more information about any command.
Navigation
pwd
pwd stands for print working directory. It displays the absolute path of the directory you are currently in.
kc@kcserver:~$ pwd
/home/kc
cd stands for change directory. It is used to navigate between directories.
An absolute path starts from the root directory /, while a relative path is relative to the current working directory.
karchunt@kcserver:~/folder3$ cd ..
karchunt@kcserver:~$
karchunt@kcserver:~/folder3$ cd
karchunt@kcserver:~$
cd ~ — both navigate to your home directory.karchunt@kcserver:~$ cd folder3/innerfolder
karchunt@kcserver:~/folder3/innerfolder$
ls lists the files and directories in the current directory or a specified directory.
karchunt@kcserver:~$ ls
folder1 folder2 newfile.txt
karchunt@kcserver:~$ ls folder1
newname.txt
ls options:
| Option | Description |
|---|
-l | Long listing format with detailed info |
-a | Show all files, including hidden files (. prefix) |
-h | Human-readable file sizes (KB, MB, etc.) |
-t | Sort by modification time, newest first |
-r | Reverse the sort order |
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
...
Creating Files and Directories
mkdir
mkdir creates a new directory.
karchunt@kcserver:~$ mkdir folder1 folder2
karchunt@kcserver:~$ ls
folder1 folder2
-p flag to create all necessary parent directories:
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
innerfolder
touch
touch creates an empty file.
karchunt@kcserver:~$ touch newfile.txt
karchunt@kcserver:~$ ls
newfile.txt
Moving and Copying
mv moves or renames files and directories.
Rename a file
Move a file
karchunt@kcserver:~$ mv oldname.txt newname.txt
karchunt@kcserver:~$ ls
newname.txt
karchunt@kcserver:~$ mv newname.txt folder1/
karchunt@kcserver:~$ ls folder1
newname.txt
cp copies files and directories.
Copy a file
Copy a directory
karchunt@kcserver:~$ cp folder1/newname.txt folder2/
karchunt@kcserver:~$ ls folder2
newname.txt
Use the -r (recursive) flag to copy a directory and all its contents:karchunt@kcserver:~$ cp -r folder1/ folder3/
karchunt@kcserver:~$ ls folder3
newname.txt
Removing Files and Directories
rm removes files and directories.
Be very careful with sudo rm -rf. It force-deletes folders with superuser privileges and can permanently destroy important system files if used incorrectly. There is no recycle bin — deletion is immediate and irreversible.
Remove a file
Remove a directory
karchunt@kcserver:~$ rm folder2/newname.txt
karchunt@kcserver:~$ ls folder2
karchunt@kcserver:~$
Use the -r (recursive) flag to remove a directory and all its contents:karchunt@kcserver:~$ rm -r folder3/
karchunt@kcserver:~$ ls
folder1 folder2
Viewing File Contents
cat
cat can view file contents, create new files, or concatenate multiple files.
View a file
Create a file
Concatenate files
karchunt@kcserver:~$ cat folder1/newname.txt
This is a sample text file.
karchunt@DESKTOP-CCAQ09F:~$ cat > sample.txt
hello
HELLO
hi
karchunt@DESKTOP-CCAQ09F:~$ cat sample.txt
hello
HELLO
hi
Enter then Ctrl+D to save and exit.karchunt@kcserver:~$ cat file1.txt file2.txt
Content of file1
Content of file2
more
more views file contents one screen at a time.
karchunt@kcserver:~$ more largefile.txt
This is line 1
This is line 2
| Key | Action |
|---|
Space | Next page |
Enter | Next line |
b | Previous page |
/ + term | Search within the file |
q | Quit |
less
less is similar to more but with more advanced navigation features.
karchunt@kcserver:~$ less largefile.txt
This is line 1
This is line 2
| Key | Action |
|---|
Space | Next page |
b | Previous page |
Enter / ↓ | Next line |
↑ | Previous line |
/ + term | Search within the file |
q | Quit |
Prefer less over more for large files — it loads faster and allows both forward and backward navigation.
Other Useful Commands
echo
echo displays a line of text or the value of a variable.
kc@kcserver:~$ echo "Hello World"
Hello World
kc@kcserver:~$ echo -n "Hello World" # without trailing newline
Hello Worldkc@kcserver:~$
uptime
uptime shows how long the system has been running, along with the current time, number of logged-in users, and system load averages.
kc@kcserver:~$ uptime
14:23:58 up 7 min, 2 users, load average: 0.04, 0.03, 0.00