I was wondering if it was required by SUS, and it doesn't look like it: http://www.opengroup.org/onlinepubs/9699919799/ http://www.opengroup.org/onlinepubs/9699

I was wondering if it was required by SUS, and it doesn't look like it: http://www.opengroup.org/onlinepubs/9699919799/ http://www.opengroup.org/onlinepubs/9699919799/ . On my system running the Ubuntu distribution of GNU/Linux, it is provided by the procps package, with homepage at http://procps.sourceforge.net/ http://procps.sourceforge.net/ . I grabbed the source and had a look and there's nothing that says that it's part of GNU, nor are is the copyright owned by the FSF. Contrast this with the GNU coreutils, which mention GNU specifically in the README and have the FSF named as the copyright holder in the source files. There's very little to suggest that it's a GNU package, although calling it a "Linux" command is still technically inaccurate, I suppose, even if everyone knows what you mean. It seems to me to be like other common abuses of notation, such as saying f(x) = O(x) as opposed to f(x) \in O(x).