[jle17]

Towards 2014 or 2015 my previous work (some hosting company) had some AIX, Solaris and SCO, as well as some IBM i (aka OS 400) which isn't a Unix. AFAIK they were used because of choices of slow-moving/risk-averse big corps, mostly to run some java software or oracle/postgres/sybase databases that could just as well run on Linux.

My take on each of the OSes was:

AIX and the associated IBM stuff is kind of a mess. I encountered a bug where /etc/filesystems (fstab equivalent) was parsed differently during boot than when using the mount command manually. The focus seemed to be on the use of the menu-driven smit utility as the primary admin tool, with automation of admin tasks an afterthought. The builtin commands are often not very practical, requiring multiple steps to do things that you're used to do in one on Linux. Installing some open-source tools is essential to sanity. Some of IBM's own tools are using expect on their own software (looking at you lpar_netboot).

SCO is clearly unmaintained stuff that looks like it dates from 30 years ago. At least it's simple to use.

Solaris had some nice features, like Zones or ZFS, but much to my dismay I couldn't play with them as I was made to install an old version of the OS as the newer version wasn't listed as supported by the version of Sybase that was to be installed on it.

[spc476]

The thing I loved about AIX is SMIT (System Managment Interface Tool). Available both from the command line and GUI, you could completely manage the AIX system from it, but at any point, you could also have it print out what commands it was going to run (yes, it built a shell script as you navigated through the system). I've never seen a system like it anywhere else.

[laurentoget]

i had totally forgotten about smit - good times