RCS（Revision Control System）衍生品有两个

SCCS(Source Code Control System)

CVS（Concurrent Versions System）是一种GNU软件包，主要用于在多人开发环境下的源码的维护

现在大多数软件开发公司都使用SVN替代了CVS

1. ci check in

# ci char.c

char.c,v  <--  char.c
new revision: 1.2; previous revision: 1.1
enter log message, terminated with single '.' or end of file:
>> include //备注信息
>> .
done

2. co check out

# co char.c //只读co

char.c,v  -->  char.c
revision 1.2
done

# co -l char.c //加锁co

char.c,v  -->  char.c
revision 1.3 (locked)
done

只有一个用户有写权限

# co -l char.c //co失败

char.c,v  -->  char.c
co: char.c,v: Revision 1.3 is already locked by root.

3. rlog

查看文件的改动清单

# rlog char.c

RCS file: char.c,v
Working file: char.c
head: 1.3
branch:
locks: strict
access list:
symbolic names:
keyword substitution: kv
total revisions: 3; selected revisions: 3
description:
hello

4. rcsdiff

查看两个修订版之间的改动

# rcsdiff -r1.1 -r1.2 char.c
===========================================================
RCS file: char.c,v
retrieving revision 1.1
retrieving revision 1.2
diff -r1.1 -r1.2
1a2
> #include <stdio.h> //改动