gzip and gunzip in Linux CLI - Step-by-Step Execution

Concept Flow - gzip and gunzip

Start with file

↓

Run gzip

↓

File compressed to .gz

↓

Run gunzip

↓

File decompressed back

↓

End

This flow shows compressing a file with gzip and then decompressing it with gunzip.

Execution Sample

Linux CLI

echo "Hello World" > file.txt
gzip file.txt
ls
gunzip file.txt.gz
ls

Create a text file, compress it with gzip, list files, decompress with gunzip, then list files again.

Execution Table

Step	Command	Action	File State	Output
1	echo "Hello World" > file.txt	Create file.txt with text	file.txt exists
2	gzip file.txt	Compress file.txt to file.txt.gz and remove original	file.txt.gz exists, file.txt removed
3	ls	List files	file.txt.gz exists	file.txt.gz
4	gunzip file.txt.gz	Decompress file.txt.gz to file.txt and remove .gz	file.txt exists, file.txt.gz removed
5	ls	List files	file.txt exists	file.txt

💡 All commands executed successfully; file compressed and decompressed as expected.

Variable Tracker

File	Initial	After gzip	After gunzip
file.txt	exists	removed	exists
file.txt.gz	does not exist	exists	removed

Key Moments - 2 Insights

Why does file.txt disappear after running gzip?

gzip compresses the file and replaces the original with the compressed .gz file, so file.txt is removed as shown in step 2 of the execution_table.

What happens if you run gunzip on a file that is not compressed?

gunzip expects a .gz file; if the file is not compressed or missing .gz extension, it will give an error and not decompress, unlike step 4 where file.txt.gz exists.

Visual Quiz - 3 Questions

Look at the execution_table, after which step does file.txt.gz first appear?

A Step 2

B Step 1

C Step 3

D Step 4

💡 Hint

Check the 'File State' column for file.txt.gz presence after each step.

At which step does file.txt reappear after being compressed?

A Step 2

B Step 4

C Step 3

D Step 5

💡 Hint

Look at the 'File State' column to see when file.txt exists again.

If you skip the gunzip command, what will the final ls output show?

A file.txt only

B both file.txt and file.txt.gz

C file.txt.gz only

D no files

💡 Hint

Refer to step 3 where gzip has compressed the file but gunzip has not run yet.

Concept Snapshot

gzip compresses files by replacing the original with a .gz file.
gunzip decompresses .gz files back to original and removes the .gz.
Use gzip filename to compress and gunzip filename.gz to decompress.
After gzip, original file is gone; after gunzip, original file returns.
Check files with ls to see changes.

Full Transcript

This lesson shows how gzip compresses a file by creating a .gz file and removing the original. Then gunzip decompresses the .gz file back to the original file and removes the compressed version. We start by creating a file with echo, compress it with gzip, list files to see the .gz file, then decompress with gunzip and list files again to see the original file restored. gzip replaces the original file with the compressed one, so the original disappears after compression. gunzip reverses this. If you try to gunzip a file that is not compressed, it will error. This visual trace helps understand the file state changes step-by-step.

Practice

1. What does the gzip command do in Linux?

easy

A. Lists files in a directory

B. Deletes a file permanently

C. Compresses a file and replaces the original with a .gz file

D. Creates a backup copy of a file

Solution

1. Step 1: Understand gzip purpose

   The gzip command compresses files to save disk space.

2. Step 2: Effect on original file

   It replaces the original file with a compressed file ending in .gz.

3. Final Answer:

   Compresses a file and replaces the original with a .gz file -> Option C

4. Quick Check:

   gzip compresses files = D [OK]

Hint: gzip compresses and replaces original file by default [OK]

Common Mistakes:

• Thinking gzip deletes files without compression
• Confusing gzip with backup commands
• Assuming gzip lists files

2. Which of the following is the correct syntax to compress a file named data.txt but keep the original file?

easy

A. gzip data.txt

B. gzip -d data.txt

C. gunzip -k data.txt

D. gzip -k data.txt

Solution

1. Step 1: Identify option to keep original

   The -k option tells gzip to keep the original file after compression.

2. Step 2: Match correct command

   gzip -k data.txt compresses and keeps the original file.

3. Final Answer:

   gzip -k data.txt -> Option D

4. Quick Check:

   Use -k to keep original file [OK]

Hint: Use -k with gzip to keep original file [OK]

Common Mistakes:

• Using gunzip instead of gzip for compression
• Using -d which is for decompression
• Not using -k and losing original file

3. What will be the output of the following commands?

gzip -k report.txt
gunzip report.txt.gz

medium

A. Only report.txt exists after commands

B. Both report.txt and report.txt.gz exist after commands

C. Original report.txt deleted, only report.txt.gz remains

D. Error because gunzip cannot decompress .gz files

Solution

1. Step 1: Analyze gzip -k report.txt

   This compresses report.txt to report.txt.gz and keeps the original report.txt file.

2. Step 2: Analyze gunzip report.txt.gz

   This decompresses report.txt.gz back to report.txt and deletes the .gz file.

3. Final Answer:

   Only report.txt exists after commands -> Option A

4. Quick Check:

   gzip -k keeps original, gunzip restores and removes .gz [OK]

Hint: gunzip removes .gz file after decompression [OK]

Common Mistakes:

• Assuming gzip deletes original with -k option
• Thinking gunzip keeps .gz file after decompression
• Confusing gzip and gunzip roles

4. You run gunzip file.txt but get an error saying "not in gzip format." What is the likely problem?

medium

A. gunzip command is misspelled

B. file.txt is not a compressed .gz file

C. file.txt is already decompressed

D. You need to use gzip instead of gunzip

Solution

1. Step 1: Understand gunzip input requirement

   gunzip expects a file compressed with gzip, usually ending with .gz.

2. Step 2: Analyze error message

   "not in gzip format" means the file is not compressed or not a .gz file.

3. Final Answer:

   file.txt is not a compressed .gz file -> Option B

4. Quick Check:

   gunzip needs .gz files [OK]

Hint: gunzip only works on gzip-compressed (.gz) files [OK]

Common Mistakes:

• Trying to decompress uncompressed files
• Confusing gzip and gunzip commands
• Ignoring file extensions

5. You have multiple log files: log1.txt, log2.txt, and log3.txt. You want to compress all of them but keep the original files. Which command will do this correctly?

hard

A. gzip -k log*.txt

B. gzip log*.txt

C. gunzip -k log*.txt

D. gzip -d log*.txt

Solution

1. Step 1: Identify command to compress multiple files

   gzip compresses files; log*.txt matches all log files.

2. Step 2: Ensure original files are kept

   The -k option keeps original files after compression.

3. Final Answer:

   gzip -k log*.txt -> Option A

4. Quick Check:

   gzip -k compresses and keeps originals [OK]

Hint: Use gzip -k with wildcard to keep originals [OK]

Common Mistakes:

• Using gunzip instead of gzip for compression
• Not using -k and losing original files
• Using -d which decompresses files