Compression & Archiving – Linux Teaching Plan

1. gzip – Lossless File Compression

# Compress a single file
gzip -c largefile.txt > largefile.txt.gz

# Decompress
gzip -d -c largefile.txt.gz > largefile-decompressed.txt

# Show compression ratio
gzip -l largefile.txt.gz

• Compress /var/log/syslog and note the size before/after.
• Compress a directory tree using tar -czf (see tar below).

2. bzip2 – High Compression Ratio

# Compress
bzip2 -k myfile.txt       # -k keeps the original

# Decompress
bunzip2 myfile.txt.bz2

# View info
bzip2 -l myfile.txt.bz2

• Compress a large text corpus with bzip2 -9 (max compression) and compare speed vs gzip.
• Create a multi‑file archive with tar -cjvf and inspect with tar -tvf.

3. xz – Very High Compression

# Compress
xz -z -k -9 file.txt

# Decompress
xz -d -k file.txt.xz

# Show stats
xz -l file.txt.xz

• Compress a binary release (e.g., a .deb package) with xz -9 and compare with gzip.
• Use tar -Jcvf to create an .tar.xz archive of a source tree.

4. lz4 – Speed over Ratio

# Compress
lz4 -k file.txt

# Decompress
lz4 -d file.txt.lz4 -o file-decompressed.txt

# Benchmark
time lz4 -k largefile.txt
time gzip -k largefile.txt

• Compress a log archive with lz4 -9 and measure speed vs gzip.
• Use tar --use-compress-program=lz4 -cvf to archive a directory.

5. zstd – Balanced Speed & Ratio

# Compress
zstd -k -19 file.txt

# Decompress
unzstd -k file.txt.zst

# Inspect
zstd --list file.txt.zst

• Compress a media library with zstd -19 and benchmark against xz.
• Create an .tar.zst archive with tar --use-compress-program=zstd -cvf.

6. pigz – Parallel Gzip

# Compress using all CPUs
pigz -k file.txt

# Decompress
pigz -d -k file.txt.gz

# Compare performance
time pigz -k file.txt
time gzip -k file.txt

• Compress a large dataset (csv) with pigz and note speed improvements.
• Integrate pigz into a tar command: tar -cf - dir/ | pigz -c > dir.tar.gz.

7. tar – Archive Multiple Files

# Create a gzip archive
tar -czvf project.tar.gz project/

# Create an xz archive
tar -cJvf project.tar.xz project/

# List contents
tar -tvf project.tar.gz

# Extract specific file
tar -xvf project.tar.gz path/to/file.txt

• Archive the /etc directory and extract only hostname.
• Create a split archive: tar -cvf - dir/ | split -b 100M - dir.tar.

8. zip / unzip – Portable Archiving

# Recursive zip
zip -r archive.zip src/ docs/

# Add files
zip archive.zip readme.md

# List
zipinfo archive.zip

# Extract
unzip archive.zip -d extracted/

• Zip a web project (public/) and verify that only files with .html and .css are present.
• Use zip -j to create a ZIP that contains only the file names, no paths.

9. 7z – High Compression & AES‑256

# Create archive with 7z
7z a -tzip -mx=9 archive.zip folder/

# Add encrypted file
7z a -pMySecret -mem=AES256 secure.7z secret.txt

# List contents
7z l archive.zip

# Extract
7z x archive.zip -oextracted/

• Compress a backup folder with -m0=BCJ2 -mx=9 and observe the size.
• Encrypt a single file and decrypt it with the correct password.

10. ar – Archive Static Libraries

# Create an object file
gcc -c foo.c -o foo.o

# Build a static lib
ar rcs libfoo.a foo.o

# List archive contents
ar -t libfoo.a

# Extract a file
ar -x libfoo.a foo.o

• Create a static library from two source files and link it to a program.
• Show that ar -d can delete an object from the archive.

11. split / cat – Multi‑volume & Splitting

# Split a large file into 50 MB pieces
split -b 50M largefile.bin part_

# Reassemble
cat part_* > largefile-assembled.bin

# Split an archive
tar -cvf - data/ | split -b 200M - data.tar.part_

# Reconstruct & extract
cat data.tar.part.* | tar -xvf -

• Split a 2 GB database dump into 200 MB parts and copy them to a removable drive.
• Reassemble the parts on another machine and verify checksum.

Mini‑Project: Incremental Backup & Restore

Students will write a Bash script backup.sh that:

1. Creates a timestamped directory backups/YYYYMMDD-HHMMSS.
2. Uses tar with -I pigz -c to archive /var/www and /etc, storing the archive as www.tgz and etc.tgz.
3. Creates a .gz archive for each log file in /var/log using gzip -9.
4. Compresses the backup directory with 7z a -tzip -mx=9 to produce a single backup.zip.
5. Provides a restore.sh that can extract the archive and restore files to their original locations.

Deliverables: backup.sh, restore.sh, README.md explaining the workflow, and a video demo.

Assessment & Wrap‑up

1. Quiz (5 questions) – 3‑choice MC covering gzip vs bzip2 vs xz vs lz4 vs zstd.
2. Hands‑on test – Run a command chain that compresses /etc/nginx with tar -cJvf, splits it into 100 MB pieces, and later reassembles it.
3. Project Demo – Students present their backup script, explain compression choices, and show a successful restore.

Score sheet (out of 35 points):