AIX

IBM AIX

Back in the day (late 1990's) I worked with AIX a fair bit while at a company which had multiple platforms: Sun, IBM, HP. We mostly worked with the Suns, however I eventually came to terms with AIX after spending several weeks straight working with them. My description of AIX was "AIX makes perfect sense as long as you stand up and bang your head against the wall every 10 minutes. Unfortunately, once AIX makes sense, nothing else does."

Thus the refrain: AIX: there's never a brick wall around when you need one.