bash Cookbook

RCS

RCS was a revolution in its time, and is the underlying basis for CVS.

Pros

• It’s better than nothing.

Cons

• Does not allow concurrent access to the same file.

• Does not have the inherent concept of a central repository, though you can go out of your way to create one using symbolic links.

• No concept of remote repositories.

• Only tracks changes to files, and does not store or consider directories at all.

• Poor support for binary files, and no support for other objects such as symbolic links. Unlike CVS or SVN, which have a single main end-user binary, RCS is a collection of binaries.

Example

Create a new script directory for personal use in a home directory:

/home/jp$ mkdir -m 0754 bin

Create some scripts:

/home/jp$ cd bin

/tmp/scripts/bin$ cat << EOF > hello
> #!/bin/sh
> echo 'Hello World!'
> EOF

/home/jp/bin$ ci hello
hello,v  <--  hello
enter description, terminated with single '.' or end of file:
NOTE: This is NOT the log message!
>> Obligatory Hello World
>> .
initial revision: 1.1
done

/home/jp/bin$ ls -l
total 4.0K
-r--r--r--  1 jp jp 228 Jul 20 02:25 hello,v

Huh? What happened? It turns out that if a directory called RCS does not exist, the current directory is used for the RCS file. And if the -u or -l switches are not used, the file is checked in and then removed. -l causes the file to be checked back out and locked so you can edit it, while -u is unlocked (that is, read-only). OK, let’s try that again. First, let’s get our file back, then create an RCS directory and check it in again. ...