I recently used sudo apt install on my Linux Virtual Machine to get funny commands like cowsay and Telnet Star Wars and, I was wondering, what does the command actually install from? What does it take the code from?

  • 1
    from the repository that is configured on your local machine: see man 5 sources.list – brynk Feb 8 at 22:17
  • It should also be noted that your repositories likely have mirrors, so it's from a repository located on a specific mirror. Not all repositories have mirrors. – KGIII Feb 8 at 23:52
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    Does this answer your question? How does apt-get really work?, Also unix.stackexchange.com/questions/521328/… – muru Feb 9 at 2:36

Packages are downloaded from the repositories ("repos") and installed. The repos are configured in /etc/apt/ but can be listed with apt-cache policy:

$ apt-cache policy
Package files:
 100 /var/lib/dpkg/status
     release a=now
 500 http://security.ubuntu.com/ubuntu focal-security/multiverse i386 Packages
     release v=20.04,o=Ubuntu,a=focal-security,n=focal,l=Ubuntu,c=multiverse,b=i386
     origin security.ubuntu.com
 500 http://security.ubuntu.com/ubuntu focal-security/multiverse amd64 Packages
     release v=20.04,o=Ubuntu,a=focal-security,n=focal,l=Ubuntu,c=multiverse,b=amd64
     origin security.ubuntu.com

Each package can be examined in detail with apt show like this:

$ apt show cowsay
Package: cowsay
Version: 3.03+dfsg2-7
Homepage: https://web.archive.org/web/20120527202447/http://www.nog.net/~tony/warez/cowsay.shtml
Download-Size: 18.5 kB
APT-Sources: http://mirrors.linode.com/ubuntu focal/universe amd64 Packages
Description: configurable talking cow

As you can see, the APT-Sources line will tell you which repository the package came from, and the Homepage line tells you where the code originally came from.

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