The files which had to be rewritten are described in two articles written by Bill and Lynne Jolitz, who implemented the missing functionality for their distribution, 386BSD: Missing Pieces I and Missing Pieces II (part of a long series of articles published in Dr. Dobb’s Journal).
They list the missing features as follows:
clists: character lists, ...
$HOSTNAME was added to bash in 2.0 released in December 1996.
Changelog says it was implemented on 1995-08-01.
$HOST was added to zsh-2.0 released in 1991.
It was already in tcsh in 1987.
I can only assume the bash authors thought HOSTNAME was a better name than HOST, and I can see their point considering that bash also had a $HOSTTYPE variable (like tcsh) ...
A partial answer, namely on the contents of the variables:
The values of all variables come from a call to gethostname(2):
tcsh sh.c: main() Default: unknown.
bash shell.c: shell_initialize(). Default: ??host??
zsh param.c: createparamtable()
The default values are:
Interestingly, zsh doesn't check the return ...
In bash, to prevent a command from being added to history, put a space before the command. This is assumes that you have, as is common, the ignorespace option set in HISTCONTROL. If you don't, run the following command (or add it to ~/.bashrc to make it permanent):
Many people also want to ignore duplicate commands, in which ...
From what I recall (there's been plenty of videos of Linus Torvalds discussing the origins of Linux), Linus, while at University or college, was doing a lot of work using Minix ("Mini-Unix," another Unix-derived system, where Unix had been around since the 1970's). As a kind of pet project during this time, He began developing His own kernel in ...
Linus borrowed ideas from Unix
Technically, Linus wanted to build something like Minix, the Unix Like OS written by Andrew S Tanenbaum. Source Code of Minix wasn't available. Linux was inspired to go One Upon Minix & he succeeded.
Ken Thompson, Dennis Ritchie should be the fathers of Linux
Thompson & Ritchie wrote Unix yes, but Unix was Closed ...
The short answer: Linus doesn't take all the credit. He acknowledges that his is not the only effort in maintaining Linux. His is, however, the effort that wrote the first kernel of Linux, so the lion's share of the credit (IMHO) is rightly his.
The longer version of this answer could easily produce several doctoral theses, either in computer science or ...