Is Kernighan & Ritchie "The C Programming Language" public domain? [Solved]

[curtvaughan]

I have found some PDF copies of K&R available at several web sites for download (both first and second editions). Is it legal to download or supply links to the aforesaid web sites? I was on a programming forum and posted one of the links as a suggestion for getting a historical grasp on C, but was warned by a moderator that the book is still under copyright. Does anyone know if that is the case? I just assumed that after 30 years it was public domain, but being originally written in a Unix environment, perhaps it still can't be freely distributed. The moderator wasn't sure, but said he removed it until I or he could find out the copyright status. Any help appreciated.

[catweazel]

That book is still available for purchase so I'd be inclined to say it's an illegal download.

[curtvaughan]

I'm coming to that conclusion. The PDF versions on the internet seem to mostly originate from university websites. I'm guessing they're meant to be available to students in classes, with some sort of educational leeway allowed by the copyright owners. If people take the copyright seriously, these websites need to be made inaccessible to the public. Anyway, lesson learned. I've found a lot of old hardware and software manuals online like this: Grishman's Compass Assembly language book in reference to the CDC/Cyber 6000/7000 mainframes, DEC PDP-11 documents, and so forth, mostly dating from 40 or more years ago. Like K&R, i get them for my own historical/nostalgic gratification, having worked with the hardware and software they represent in the past. Anyway, I will refrain from supplying such links in the future. Apparently 74 years is the standard length of time needed before public domain takes over.