Introduction to the Linux Command Line

Linux offers a flexible terminal interface for managing files and directories. While graphical tools are useful for basic tasks, the command-line interface (CLI) gives users access to advanced operations and precise control over file organization.

Basic File and Directory Commands

• cp: Copy files and directories
• mv: Move or rename files and directories
• mkdir: Create directories
• rm: Delete files and directories
• ln: Create hard or symbolic links

Using Wildcards to Select Files

Wildcards (globbing patterns) help match multiple filenames using character-based rules:

Pattern	Meaning
*	Matches any number of characters
?	Matches a single character
[abc]	Matches one of the listed characters
[!abc]	Matches any character except those listed
[[:digit:]]	Matches any digit

Creating Directories with mkdir

mkdir dir1 dir2 dir3

This creates three directories: dir1, dir2, and dir3.

Copying Files with cp

cp file1 file2        # Simple copy
cp -i file1 file2    # Prompt before overwrite
cp -r dir1 dir2      # Recursively copy directories

Useful Options:

Option	Description
-a	Preserve attributes (owner, permissions)
-u	Copy only newer or missing files
-v	Verbose output

Moving and Renaming with mv

mv file1 file2       # Rename file1 to file2
mv file1 file2 dir1  # Move to directory

Deleting with rm

rm file1             # Simple delete
rm -r dir1          # Recursive directory deletion
rm -rf dir1         # Force delete without prompt

Creating Links with ln

Hard Link:

ln file fun-hard

Symbolic Link:

ln -s file fun-sym

Hard Link vs Symbolic Link

Feature	Hard Link	Symbolic Link
Points To	File inode	File path
Partition Scope	Same partition only	Cross-partition allowed
File Removal	Link remains valid	Link breaks

Setting Up a Test Environment

cd ~
mkdir playground
cd playground
mkdir dir1 dir2

Copy a system file for testing:

cp /etc/passwd .

Renaming and Moving Files

mv passwd fun
mv fun dir1
mv dir1/fun dir2
mv dir2/fun .

Creating Hard and Symbolic Links

ln fun fun-hard
ln fun dir1/fun-hard
ln -s fun fun-sym
ln -s ../fun dir1/fun-sym

Deleting Links and Files

rm fun-hard          # Decreases link count
rm -i fun           # Deletes original file
rm fun-sym          # Deletes broken symlink

Cleaning Up the Playground

rm -r playground

Conclusion

Linux’s CLI tools offer robust and precise control for managing files, directories, and links. By mastering commands like cp, mv, rm, mkdir, and ln, along with wildcard usage and symbolic link behaviors, users gain the ability to organize and manipulate the file system efficiently.