How do you check the OS version of an AS400 system?

There are several ways to check the OS version of an AS400 system (which is now more commonly referred to as IBM i):

1. Using the DSPPTF command:

This is generally considered the most reliable method.
Type DSPPTF on the command line and press Enter.
The OS version will be displayed at the top of the screen. For example, you might see something like "V7R1M0", which means Version 7 Release 1 Modification level 0.

2. Using the GO LICPGM command:

Type GO LICPGM on the command line and press Enter.
Select option 10 (Display installed licensed programs).
Press F11 (Display release).
Look for the entry with the description "Operating System/400". The version will be displayed in the Release column.

3. Using the DSPSFWRSC command:

4. Checking spool files:

Important Notes:

AS400 is an outdated term: The system has evolved over the years and is now officially called IBM i. However, many people still use the term AS400.
Tech Refreshes (TRs): Starting with version 7.1, IBM introduced Tech Refreshes to provide more frequent updates. So, in addition to the version number, you might also need to know the TR level to determine the exact capabilities of the OS. You can find the TR level using the DSPPTF 5770999 command.
DB2 is integrated: The database system (DB2) is an integral part of the IBM i operating system, not a separate product. Therefore, you don't need to check the DB2 version separately. The OS version will indicate the DB2 capabilities.