Linux cp Command: File Copying

Introduction

In this lab, you'll explore the powerful cp command in Linux, an essential tool for file and directory management. You'll learn how to efficiently copy files and directories, understand various options to customize the copying process, and apply these skills in practical scenarios. By the end of this lab, you'll be comfortable using cp for everyday file management tasks and backups.

Skills Graph

Understanding the Basic cp Command

The cp command is fundamental for duplicating files in Linux. Let's start with a simple scenario where you need to create a backup of an important document.

In your project directory (~/project), there's a file named important_report.txt. Your task is to create a backup of this file in the same directory.

First, let's check the contents of your project directory:

ls ~/project

You should see important_report.txt listed among other files. Don't worry if you see additional files; we'll focus on important_report.txt for now.

Now, let's create a backup:

cp ~/project/important_report.txt ~/project/important_report_backup.txt

This command creates a copy of important_report.txt named important_report_backup.txt in the same directory. Here's what each part of the command means:

• cp: This is the command for copying files.
• ~/project/important_report.txt: This is the source file we want to copy. The ~ symbol represents your home directory.
• ~/project/important_report_backup.txt: This is the destination file. We're creating a new file with "_backup" added to the name.

To verify the copy was created successfully, list the contents of the directory again:

ls ~/project

You should now see both important_report.txt and important_report_backup.txt. If you don't see the new file, double-check that you typed the cp command correctly.

Copying Files to Different Directories

Often, you'll need to copy files to different locations. Let's simulate a scenario where you're organizing your music collection.

First, let's check if the music directory exists:

ls ~/project

You should see a directory named music listed. If it's not there, don't worry; it was created in the setup script.

Now, let's copy a music file from your project directory to the music directory:

cp ~/project/favorite_song.mp3 ~/project/music/

This command copies favorite_song.mp3 from your project directory to the music directory. Let's break down the command:

• cp: The copy command.
• ~/project/favorite_song.mp3: The source file we're copying.
• ~/project/music/: The destination directory. Notice the trailing slash (/) - this tells cp that music is a directory.

To verify the file was copied successfully, list the contents of the music directory:

ls ~/project/music

You should see favorite_song.mp3 listed. If you don't see it, make sure you typed the cp command correctly and that favorite_song.mp3 exists in your project directory.

Copying Multiple Files at Once

You can copy multiple files in a single command, which is useful for batch operations. Let's organize your document collection.

First, let's check if the documents directory exists:

ls ~/project

You should see a directory named documents listed.

Now, let's copy multiple text files to this documents directory:

cp ~/project/report1.txt ~/project/report2.txt ~/project/notes.txt ~/project/documents/

This command copies report1.txt, report2.txt, and notes.txt to the documents directory. Here's how it works:

• cp: The copy command.
• ~/project/report1.txt ~/project/report2.txt ~/project/notes.txt: These are the source files we're copying. You can list as many files as you need, separated by spaces.
• ~/project/documents/: This is the destination directory.

Verify the files were copied:

ls ~/project/documents

You should see all three files (report1.txt, report2.txt, and notes.txt) listed. If any are missing, double-check the cp command for typos.

Using the -i Option for Interactive Copying

When copying files, you might encounter situations where the destination already contains a file with the same name. The -i option makes cp interactive, prompting you before overwriting existing files.

Let's simulate this scenario:

First, let's see the content of an existing file:

cat ~/project/test_file.txt

Tips: If you're unfamiliar with the cat command, don't worry; it will be explained in detail later.

You should see "Original content" displayed.

Now, let's try to copy a file with the same name:

cp -i ~/project/new_test_file.txt ~/project/test_file.txt

When prompted, type y and press Enter to overwrite the file. If you don't want to overwrite, type n and press Enter.

The -i option stands for "interactive". It tells cp to ask for confirmation before overwriting any existing files. This is a safety measure to prevent accidental data loss.

Now, check the content of the file:

cat ~/project/test_file.txt

If you chose to overwrite, you should see "New content" displayed. If not, you'll still see "Original content".

Recursive Copying with the -r Option

The -r option allows you to copy directories and their contents recursively. This is particularly useful for backing up entire directory structures.

Let's create a backup of the entire website directory:

cp -r ~/project/website ~/project/website_backup

This command copies the website directory and all its contents to a new directory called website_backup. Here's what each part means:

• cp: The copy command.
• -r: This option stands for "recursive". It tells cp to copy directories and their contents.
• ~/project/website: This is the source directory we're copying.
• ~/project/website_backup: This is the new directory where we're copying everything.

Verify the backup was created successfully:

ls -R ~/project/website_backup

You should see the entire directory structure and files listed. The -R option with ls shows the contents of directories recursively.

If you don't see the expected structure, make sure you typed the cp -r command correctly.

Preserving File Attributes with the -p Option

When copying files, you might want to preserve the original file's attributes such as timestamps and permissions. The -p option does this for you.

Let's demonstrate this:

First, let's look at the attributes of the original file:

ls -l ~/project/old_file.txt

Note the date and time shown.

Now, let's copy the file while preserving its attributes:

cp -p ~/project/old_file.txt ~/project/preserved_file.txt

The -p option stands for "preserve". It maintains the original file's modification time, access time, and permissions.

Let's compare the attributes of both files:

ls -l ~/project/old_file.txt ~/project/preserved_file.txt

You should see that both files have the same date and time. If they differ, make sure you used the -p option with cp.

Using Wildcards for Selective Copying

Wildcards allow you to copy multiple files based on patterns. This is useful when you want to copy files of a certain type or with specific naming conventions.

Let's copy all text files to the text_files directory:

cp ~/project/*.txt ~/project/text_files/

And copy all PDF files to the pdf_files directory:

cp ~/project/*.pdf ~/project/pdf_files/

Here's what the wildcard (*) means:

• *.txt matches any file that ends with ".txt"
• *.pdf matches any file that ends with ".pdf"

This allows you to copy multiple files without listing them individually.

Verify the files were copied correctly:

ls ~/project/text_files
ls ~/project/pdf_files

You should see all .txt files in the text_files directory and all .pdf files in the pdf_files directory.

Summary

In this lab, you've mastered the essential uses of the Linux cp command. You've learned how to:

1. Copy single files
2. Copy files to different directories
3. Copy multiple files at once
4. Use the -i option for interactive copying
5. Recursively copy directories with the -r option
6. Preserve file attributes with the -p option
7. Use wildcards for selective copying

Additional cp options not covered in this lab include:

• -u: Copy only when the source file is newer than the destination file or when the destination file is missing
• -v: Verbose mode, explaining what is being done
• -n: No clobber; do not overwrite an existing file
• -l: Create hard links instead of copying files
• -s: Create symbolic links instead of copying files

The cp command is a powerful tool for file management in Linux. With these skills, you're now equipped to handle a wide range of file copying tasks efficiently and effectively.

Resources

• Linux Roadmap - roadmap.sh