linux - /etc/rc.d what does rc stand for?
2014-04
user3134198
This question already has an answer here:
Fiasco Labs
It's all based off of Bell Labs System V Unix which was somewhere around when init and run levels were introduced.
It stands for runcom or run commands. In the question of anything Unix, consult the Jargon File. There's a deep history, canonical and recorded that came before Linux
:rc file: /R·C fi:l/, n.
[Unix: from runcom files on the {CTSS} system 1962-63, via the startup script /etc/rc] Script file containing startup instructions for an application program (or an entire operating system), usually a text file containing commands of the sort that might have been invoked manually once the system was running but are to be executed automatically each time the system starts up. See also {dot file}, {profile} (sense 1).
suspectus
It is derived from "run commands".
From Unix FAQ
rc (as in ".cshrc" or "/etc/rc") = "RunCom" "rc" derives from "runcom", from the MIT CTSS system, ca. 1965.
'There was a facility that would execute a bunch of commands stored in a file; it was called "runcom" for "run commands", and the file began to be called "a runcom." "rc" in Unix is a fossil from that usage.'
Brian Kernighan & Dennis Ritchie, as told to Vicki Brown "rc" is also the name of the shell from the new Plan 9 operating system.
stvie
rc.d contains runlevels, I vote for runlevel control or possibly runlevel config
I don't think it's related to bashrc
Matthew Williams
I thought it stood for Run Command, but the guys over at linuxquestions have a couple positions on it.
So it's probably one of these:
- run commands
- resource control
- run control
- runtime configuration
Sorry I can't give you a more specific answer.
Questioner
Well we all know that it holds passwords. But cat-ing it gives out nothing. Not even encrypted gibberish. So how exactly is a password stored in this? Is this like a device file or something?
David Thornley
For a little historical background:
Long ago, there was the /etc/passwd file that held all sorts of information about the user, including not only an encrypted version of the user's password, but things like the user's home directory, groups, default shell, and name. This was handy, and lots of system utilities used the /etc/passwd file for various purposes. The practice of storing only an encrypted version of the password was a great advance over storing the real password in a (hopefully) protected file, and the encryption algorithm could be tuned to be fast enough to be practical but slow enough to make brute force cracking impractical with contemporary hardware.
Back then, Unix was usually used in research and academic environments, and security wasn't a big deal (which turned out to be a bad idea in 1988, with the Robert Morris worm). As it was used in more hostile environments, and as computer power improved, it was less and less practical to rely on encryption alone, and so it became desirable to move the passwords to a less accessible file.
Now, there were very large numbers of programs of varying sorts that used /etc/passwd for the information buried there, and it was not practical to go through and change them all. Therefore, the passwords were put into a new file (often /etc/shadow), which was locked down as much as possible to all accounts except root, and all the other information was left behind.
Márton Molnár
See here.
cjg
On linux the passwords are stored in /etc/shadow and on BSD systems they are stored in /etc/master.passwd.
Ivan Petrushev
Storing passwords in /etc/password is sooo waay in the past. /etc/passwd is used for storing simple user information like UID, username, real name, etc. It also has a field that tells you if the account has a password, and if it does, you should look in /etc/passwd