Linux Tips

Linux Package Comparison: Find Differences Between 2 Servers

- by John Britto - Leave a Comment - 1 min read
Quick Linux Tip #95:

Question: Two servers behave differently. Which packages differ between them?

Try: diff <(ssh linuxteck@server1 'dpkg -l | awk "/^ii/{print \$2}"' | sort) <(ssh linuxteck@server2 'dpkg -l | awk "/^ii/{print \$2}"' | sort)

Info: dpkg -l lists installed packages, filtered via awk for active (ii) entries. Process substitution pipes remote outputs directly into diff to spot package drift.

Examples:

  • $ diff <(rpm -qa | sort) <(ssh host2 'rpm -qa | sort')  # Compare RHEL/Fedora packages
  • $ diff <(pacman -Q | sort) <(ssh host2 'pacman -Q | sort')  # Compare Arch Linux packages
  • $ comm -23 <(dpkg -l) <(ssh host2 'dpkg -l')  # Show packages unique to server1

Note: SSH public key authentication must be configured for passwordless remote execution. Essential for auditing differences between staging and production environments.




LinuxTeck.com 
linuxteck:~$ diff <(ssh linuxteck@server1 'dpkg -l | awk "/^ii/{print \$2}"' | sort) <(ssh linuxteck@server2 'dpkg -l | awk "/^ii/{print \$2}"' | sort)
23a24
> fail2ban
45d45
< postgresql-14
67a68
> redis-server
89d89
< snapd

linuxteck:~$ ssh linuxteck@server1 'dpkg -l | grep -c "^ii"'
1234

linuxteck:~$ ssh linuxteck@server2 'dpkg -l | grep -c "^ii"'
1256

linuxteck:~$

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About John Britto

John Britto Founder & Chief-Editor @LinuxTeck. A Computer Geek and Linux Intellectual having more than 20+ years of experience in Linux and Open Source technologies.

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