Reading gz files with zcat
The Debian Policy Manual dictates that all packages should come with documentation. In order to save space in the debian archive these documents need to be compressed with gzip. There are a ton of these files floating around in the /usr/share/doc directory. Recently I wanted to read some of the documentation. If you try to open the file with cat it spits out binary gibberish. You can of course unzip the file as you normally would and open it up that way, but it turns out there is an easier way. Using zcat you can read the contents of compressed files just like you would with cat.
zcat is identical to gunzip -c. (On some systems, zcat may be installed as gzcat to preserve the original link to compress.) zcat uncompresses either a list of files on the command line or its standard input and writes the uncompressed data on standard output. zcat will uncompress files that have the correct magic number whether they have a .gz suffix or not. GZIP(1) man page.By default, this will put all of the output into your terminal window, which is fine for most files. The other place where this can come in handy is when you are trying to look through compressed log files. In this case, having to scroll around the terminal may not be a great option. You can pipe the output of zcat into other programs such as
less in order to be able to page through long files. For example, if I wanted to read the first 10 lines of a compressed log file, I could do so with the following command:levlaz@debvm:/var/log$ sudo zcat syslog.2.gz | head -n 10
May 2 22:27:43 debvm rsyslogd: [origin software="rsyslogd" swVersion="8.4.2" x-pid="585" x-info="https://www.rsyslog.com"] start May 2 22:27:43 debvm kernel: [ 0.000000] ACPI: LAPIC_NMI (acpi_id[0x1a] high edge lint[0x1]) May 2 22:27:43 debvm kernel: [ 0.000000] ACPI: LAPIC_NMI (acpi_id[0x1b] high edge lint[0x1]) May 2 22:27:43 debvm kernel: [ 0.000000] ACPI: LAPIC_NMI (acpi_id[0x1c] high edge lint[0x1]) May 2 22:27:43 debvm kernel: [ 0.000000] ACPI: LAPIC_NMI (acpi_id[0x1d] high edge lint[0x1]) May 2 22:27:43 debvm kernel: [ 0.000000] ACPI: LAPIC_NMI (acpi_id[0x1e] high edge lint[0x1]) May 2 22:27:43 debvm kernel: [ 0.000000] ACPI: LAPIC_NMI (acpi_id[0x1f] high edge lint[0x1]) May 2 22:27:43 debvm kernel: [ 0.000000] ACPI: LAPIC_NMI (acpi_id[0x20] high edge lint[0x1]) May 2 22:27:43 debvm kernel: [ 0.000000] ACPI: LAPIC_NMI (acpi_id[0x21] high edge lint[0x1]) May 2 22:27:43 debvm kernel: [ 0.000000] ACPI: LAPIC_NMI (acpi_id[0x22] high edge lint[0x1])
Thank you for reading! Share your thoughts with me on bluesky, mastodon, or via email.
Check out some more stuff to read down below.
Most popular posts this month
Recent Favorite Blog Posts
This is a collection of the last 8 posts that I bookmarked.
- No-One Escapes the Permanent Underclass from Fernando Borretti
- Is it ethical to use AI? from charity.wtf
- The logical destination of LLMs from Andy Bell
- Revised rules of engineering leadership. from Irrational Exuberance
- The circus freaks of open source from Drew DeVault's blog
- Clanker: A Word For The Machine from Armin Ronacher's Thoughts and Writings
- I ran a half-marathon! from gluecko.se
- My Running Tips from Kevin Bell's Blog
Articles from blogs I follow around the net
Art Doesn't Scale
Listening to two acquaintances argue about if AI art is "art" is not a new experience for me, the now eternal debate between Doomer and Boomer. In this particular context, I'm listening to it as I wait for my surprisingly expensive iced latte in downtown C...
via matduggan.com July 17, 2026i can finally talk about something i worked on!
It feels like it was about 18 months ago, but could be as long as three years ago, that my friend told me about a TV show he was developing. It was a brilliant idea, I thought. A science fiction action comedy? YES PLEASE. It was funny, and clever, and...
via WIL WHEATON dot NET July 16, 2026Generated by openring