Under CVS and RCS, you have checked out the latest version of the input.c file. What would happen if you try to check out the same file again? Why?

Question

What will be an ideal response?

Answer 1

Under RCS you can check out a read only version of a file more than once. However, you cannot check out an editable version of a file more than once. An editable version of a file can be checked out by using the co command with the -l option. If a particular revision of a file has been checked out for editing, execution of a command for checking out the same version of the file results in an exception message that gives the user the opportunity to remove the checked out version or exit. The following session illustrates the point. We checked out version 1.1 of the input.c file before issuing the co command. The command prompts the user to remove the already checked out version or abort checkout. In this case we just hit at the prompt to abort checkout.
```
$ co -l input.c
RCS/input.c,v --> input.c
revision 1.1 (locked)
done
$ co -l input.c
RCS/input.c,v --> input.c
revision 1.1 (locked)
writable input.c exists; remove it? [ny](n):
co error: checkout aborted
$
```
CVS allows you to check out the same file multiple times. When you try to commit changes to one checked out copy, CVS informs you of conflicts that may have arisen because someone else had updated the original version. In this case you need to update your file (with the cvs update input.c command) and then commit your changes to it (with the cvs commit -n “Final version” input.c command). Pages 302 and 303 of the textbook discuss this problems and its solution as outlined above.