Gzip Command in Linux

The gzip command in Linux is used to compress files efficiently, reducing their size to save disk space and speed up file transfers without data loss. It is widely used for compressing log files, backups, and large text files. By default, gzip compresses a file and replaces it with a .gz version of the same name.

• Uses the Lempel-Ziv (LZ77) compression algorithm for speed and efficiency.
• Supports decompression using the -d option or the gunzip command.
• Maintains original file metadata such as timestamp and name (unless modified).

Example 1: Compress a File Using gzip

Compress a file to reduce its size. Creates mydoc.txt.gz in the same directory and removes mydoc.txt by default.

Command:

gzip mydoc.txt

Output:

Example 2: Decompress a .gz File

Restore the original file from a compressed .gz file. This command decompresses the specified gzip file, leaving the original uncompressed file intact.

Command:

gzip -d mydoc.txt.gz

Output:

Here,

• touch mydoc.txt: Creates an empty file.
• gzip mydoc.txt: Compresses it into mydoc.txt.gz and deletes the original.
• gzip -d mydoc.txt.gz: Decompresses it back to mydoc.txt and deletes the .gz file.

Syntax

 gzip [Options] [filenames]

• gzip: Command used to compress files in Linux.
• [options]: Optional flags that modify the behavior of the command (e.g., -d, -k, -v).
• [filename]: Name of the file to be compressed.

Options Available in gzip Command

1. -k: Keep the Original File

By default, gzip deletes the original file after compression. The -k option keeps the original file along with the compressed .gz file.

Command:

gzip -k example.txt

This command compresses "example.txt" and keeps the original file intact.

Output:

Here,

1. touch example.txt: Creates an empty file named example.txt.
2. gzip -k example.txt: Compresses it into example.txt.gz while keeping the original file.
3. ls: Shows both files 'example.txt' (original) and 'example.txt.gz' (compressed).

2. -v: Verbose Mode

Displays detailed information during compression or decompression. Shows file name, original size, compressed size, and compression ratio.

Command:

gzip -v example1.txt

Output:

3. -f: Force Compression

In cases where the compressed file already exists, the -f option forcefully overwrites it. Forces compression and overwrites the existing .gz file without prompting. Useful when a compressed file with the same name already exists.

Command:

gzip -f example2.txt

Output:

Note: Compresses "example.txt" and overwrites any existing "example.txt.gz" file

4. Compress Multiple Files

gzip can compress multiple files in a single command. Each file is compressed separately into its own .gz file.

Command:

gzip file1.txt file2.txt file3.txt

Output:

gzip vs zip Commands: When to Use

The gzip and zip commands are both used for file compression in Linux, but they differ in functionality, compression method, and usage scenarios.