Archives and compression

Sooner or later you need to move a whole folder as one file. Other times you only want a smaller download. That is what archives and compression are for. tar packs many files into one. gzip shrinks a single file. zip does both, in a format other devices understand. You will use all three.

What you'll be able to do

• Pack a folder into a compressed .tar.gz archive.
• List an archive's contents without unpacking it.
• Extract an archive into the directory you choose.
• Compress and decompress a single file with gzip.
• Make and unpack a .zip archive that other apps can read.

Step 1: Create an archive with tar

tar collects files into one stream. In -czf, the c creates the archive and z compresses it with gzip. The f names the file to write. Build a small folder first.

mkdir -p project/notes
echo alpha > project/a.txt
echo beta > project/b.txt
echo gamma > project/notes/c.txt
tar -czf project.tar.gz project

A successful tar prints nothing. Check that the file exists.

ls -l project.tar.gz

-rw-r--r-- 1 u0_a123 u0_a123 214 Jan 30 10:12 project.tar.gz

The name ends in .tar.gz because it is a tar archive, then gzipped. You will also see .tgz, which means the same thing.

Step 2: List the contents before extracting

The -t flag lists an archive without unpacking it. Keep the -zf tail, so tar knows it is gzipped and where to read from.

tar -tzf project.tar.gz

project/
project/notes/
project/notes/c.txt
project/a.txt
project/b.txt

Look at those paths. Every entry is under project/. Nothing is loose at the top level. Extracting here would not scatter files across your current directory.

Step 3: Extract with tar

The -x flag extracts. Point the archive at a target directory with -C. Then it does not unpack into wherever you happen to be.

mkdir -p outdir
tar -xzf project.tar.gz -C outdir
find outdir -type f | sort

outdir/project/a.txt
outdir/project/b.txt
outdir/project/notes/c.txt

Everything landed inside outdir/project, exactly as it was packed.

Step 4: Compress a single file with gzip

gzip is for one file at a time. It replaces the file with a compressed copy that ends in .gz.

echo alpha > a.txt
gzip a.txt
ls a.txt.gz

a.txt.gz

The original a.txt is gone. In its place is a.txt.gz. To bring it back, use gunzip, which reverses the change.

gunzip a.txt.gz
cat a.txt

alpha

gzip is fast and widely used, but it works on single files. To compress a whole folder, pack it with tar first. That is why the two are so often paired.

Step 5: Use zip and unzip

The zip format is what other phones, computers and websites expect. The -r flag makes zip descend into folders.

zip -r project.zip project

  adding: project/ (stored 0%)
  adding: project/notes/ (stored 0%)
  adding: project/notes/c.txt (stored 0%)
  adding: project/a.txt (stored 0%)
  adding: project/b.txt (stored 0%)

Unlike tar, zip talks as it works. It lists each file it adds. To read the contents without unpacking, use unzip -l.

unzip -l project.zip

Archive:  project.zip
  Length      Date    Time    Name
---------  ---------- -----   ----
        0  2026-01-30 10:12   project/
        0  2026-01-30 10:12   project/notes/
        6  2026-01-30 10:12   project/notes/c.txt
        6  2026-01-30 10:12   project/a.txt
        5  2026-01-30 10:12   project/b.txt
---------                     -------
       17                     5 files

To unpack, point unzip at a folder with -d. The -q flag keeps it quiet.

mkdir -p unz
unzip -q project.zip -d unz
find unz -type f | sort

unz/project/a.txt
unz/project/b.txt
unz/project/notes/c.txt

The same warning from Step 3 applies here. List a zip before you open it.

Quick reference

Command	What it does
tar -czf out.tar.gz dir	Create a gzipped tar archive
tar -tzf out.tar.gz	List the contents without extracting
tar -xzf out.tar.gz -C dir	Extract into a chosen directory
gzip file	Compress one file, replacing it with file.gz
gunzip file.gz	Decompress a .gz file back to the original
zip -r out.zip dir	Create a zip archive of a folder
unzip -l out.zip	List a zip's contents
unzip -q out.zip -d dir	Extract a zip into a chosen directory

Next steps

• Text processing with sed and awk to inspect the files inside your archives.
• Scheduling work with cron to make a backup archive run on a timer.
• Pipe Dreams to chain listing and filtering commands.