$ stat /
  File: /
  Size: 188             Blocks: 0          IO Block: 4096   directory
Device: 0,33    Inode: 256         Links: 1
Access: (0755/drwxr-xr-x)  Uid: (    0/    root)   Gid: (    0/    root)
Access: 2023-03-16 13:11:52.876212014 +0800
Modify: 2023-09-25 09:15:24.162426570 +0800
Change: 2023-09-25 09:15:24.162426570 +0800
 Birth: 2023-03-16 13:11:52.876212014 +0800
$ stat / | awk '/Birth: /{print $2 " " substr($3,1,5)}'
2023-03-16 13:11

Linuxiac

Linux Installation Date: How to Discover Your System's Age

Want to know when your Linux system was installed? Don't wonder anymore! Here's how to do it quickly with a single simple command.