tar with compression (-z, -j, -J) in Linux CLI - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the -z option do in the tar command?

The -z option tells tar to compress or decompress the archive using gzip compression.

beginner

How do you create a bzip2 compressed tar archive named archive.tar.bz2?

Use tar -cjf archive.tar.bz2 foldername. The -j option enables bzip2 compression.

intermediate

What compression does the -J option use in tar?

The -J option uses xz compression, which often provides better compression than gzip or bzip2.

beginner

How to extract a gzip compressed tar archive named backup.tar.gz?

Use tar -xzf backup.tar.gz. The -x extracts, -z decompresses gzip, and -f specifies the file.

intermediate

Why choose -J (xz) compression over -z (gzip) or -j (bzip2)?

Because xz usually compresses files smaller than gzip or bzip2, saving more space, but it may take longer to compress or decompress.

Which tar option compresses using gzip?

A -J

B -j

C -z

D -x

The -z option uses gzip compression.

What does the -j option do in tar?

A Use bzip2 compression

B Use gzip compression

C Use xz compression

D Extract files only

The -j option tells tar to use bzip2 compression.

How do you extract an xz compressed tar archive named data.tar.xz?

A tar -xJf data.tar.xz

B tar -xjf data.tar.xz

C tar -xzf data.tar.xz

D tar -cf data.tar.xz

The -J option decompresses xz compressed archives.

Which option is NOT used for compression in tar?

A -z

B -j

C -J

D -x

The -x option is for extraction, not compression.

What command creates a gzip compressed archive named files.tar.gz from folder docs?

A tar -xzf files.tar.gz docs

B tar -czf files.tar.gz docs

C tar -cJf files.tar.gz docs

D tar -cjf files.tar.gz docs

Use -c to create, -z for gzip compression, and -f to specify the file.

Explain how to create and extract tar archives using gzip, bzip2, and xz compression options.

Think about the compression letter options and the basic tar commands for create and extract.

What are the differences between gzip, bzip2, and xz compression when used with tar?

Consider speed and compression quality differences.

Practice

1. Which option correctly describes the -z flag when used with the tar command?

easy

A. It compresses the archive using gzip.

B. It compresses the archive using bzip2.

C. It compresses the archive using xz.

D. It creates an uncompressed archive.

Solution

1. Step 1: Understand the tar compression flags

   The -z flag tells tar to use gzip compression.

2. Step 2: Match the flag to the compression type

   -z is for gzip, -j for bzip2, and -J for xz compression.

3. Final Answer:

   It compresses the archive using gzip. -> Option A

4. Quick Check:

   -z means gzip compression [OK]

Hint: Remember: z = gzip, j = bzip2, J = xz [OK]

Common Mistakes:

• Confusing -z with -j or -J
• Thinking -z creates uncompressed archive
• Mixing compression types

2. Which of the following is the correct syntax to create a bzip2 compressed tar archive named backup.tar.bz2 from the directory data?

easy

A. tar -cJf backup.tar.bz2 data

B. tar -czf backup.tar.bz2 data

C. tar -cjf backup.tar.bz2 data

D. tar -cf backup.tar.bz2 data

Solution

1. Step 1: Identify the compression flag for bzip2

   The -j flag is used for bzip2 compression.

2. Step 2: Check the full command syntax

   tar -cjf backup.tar.bz2 data creates a bzip2 compressed archive named backup.tar.bz2 from data.

3. Final Answer:

   tar -cjf backup.tar.bz2 data -> Option C

4. Quick Check:

   -j means bzip2 compression [OK]

Hint: Use -j for bzip2 compression in tar commands [OK]

Common Mistakes:

• Using -z instead of -j for bzip2
• Forgetting the 'f' flag for filename
• Mixing compression flags and extensions

3. What will be the output of the following command if the directory project contains files and subdirectories?

tar -cJf project.tar.xz project

medium

A. Creates an uncompressed tar archive named project.tar.xz

B. Creates an xz compressed tar archive named project.tar.xz

C. Creates a gzip compressed tar archive named project.tar.xz

D. Throws an error because -J is invalid

Solution

1. Step 1: Understand the -J flag

   The -J flag tells tar to use xz compression.

2. Step 2: Analyze the command output

   The command creates a compressed archive named project.tar.xz using xz compression from the project directory.

3. Final Answer:

   Creates an xz compressed tar archive named project.tar.xz -> Option B

4. Quick Check:

   -J means xz compression [OK]

Hint: Remember: -J compresses with xz, matching .tar.xz files [OK]

Common Mistakes:

• Thinking -J is invalid
• Confusing -J with -z or -j
• Assuming no compression happens

4. You run the command tar -cjf archive.tar.gz folder but get an error. What is the likely cause?

medium

A. The -f flag is missing

B. The -c flag is missing

C. The -j flag cannot be combined with .tar.gz extension

D. The folder does not exist

Solution

1. Step 1: Verify the flags and syntax

   The command has all required flags: -c for create, -j for bzip2, -f for file.

2. Step 2: Identify the likely error source

   tar will error if the source folder does not exist, typically with "Cannot stat: No such file or directory".

3. Final Answer:

   The folder does not exist -> Option D

4. Quick Check:

   Check source exists before tar [OK]

Hint: Always verify source directory exists before archiving [OK]

Common Mistakes:

• Assuming flag or extension issues
• Overlooking if folder exists
• Focusing on compression mismatch

5. You want to create a compressed archive of the logs directory using the best compression ratio available with tar. Which command should you use?

hard

A. tar -cJf logs.tar.xz logs

B. tar -cjf logs.tar.bz2 logs

C. tar -czf logs.tar.gz logs

D. tar -cf logs.tar logs

Solution

1. Step 1: Identify compression types and their ratios

   Gzip (-z) is fast but less compressed, bzip2 (-j) is better, and xz (-J) offers the best compression ratio.

2. Step 2: Choose the best compression flag

   Using -cJf creates an xz compressed archive, which has the best compression ratio.

3. Final Answer:

   tar -cJf logs.tar.xz logs -> Option A

4. Quick Check:

   Best compression = xz = -J flag [OK]

Hint: Use -J for best compression with tar [OK]

Common Mistakes:

• Choosing gzip or bzip2 for best compression
• Forgetting compression flag
• Using uncompressed tar by mistake