1 CVS Cheat Sheet for fptools hackers.
2 ------------------------------------
4 At Glasgow, we use CVS (Concurrent Version System) to keep track of
5 our sources for various software projects. CVS lets several people
6 work on the same software at the same time, allowing changes to be
7 checked in incrementally.
9 The full documentation for CVS is online, in info format (use 'info
10 cvs' or run emacs and type C-h i). A good source of tips is the CVS
11 FAQ, in /local/doc/gnu/CVS.FAQ. Bradley C. Kuszmaul provides a "to
12 the point" introduction to CVS at
14 http://arch.cs.yale.edu:8080/~bradley/cvs-instructions
16 This note is supposed to be a set of guidelines for how to use CVS at
17 Glasgow, and will probably evolve in time. The main thing to remember
18 is that most mistakes can be undone, but if there's anything you're
19 not sure about feel free to bug the local CVS meister (namely Me
20 <simonm@dcs.gla.ac.uk>).
22 The following guidelines should mean we don't step on each other's
23 toes too much. Ok, here's what you do:
25 * (only if using CVS remotely, i.e. not at Glasgow):
27 To use remote CVS, you need to supply me with a username and
28 encrypted password. Once you've done that and the account has been
29 set up, you need to do:
31 cvs -d <username>@solander.dcs.gla.ac.uk:/local/fp/src/cvsroot login
33 CVS will ask for a password. You only need to enter the password once,
34 it will be recorded in .cvspass in your home directory.
36 setenv CVSROOT :pserver:<username>@solander.dcs.gla.ac.uk:/local/fp/src/cvsroot
38 The CVSROOT environment variable will be recorded in the checked-out
39 tree, so you don't need to set this every time either. Ignore the
40 instructions for setting CVSROOT below.
42 * (ok, everybody now...) Firstly, identify which areas of the source
43 tree you'll be working on. The directory structure looks like this:
46 fptools/hslibs Haskell Libraries
49 fptools/green-card Green Card
50 fptools/nofib Nofib test suite
51 fptools/common-rts GHC/Hugs combined run-time system
53 For each directory, there's a mailing list: fp-cvs-ghc,
54 fp-cvs-hslibs etc. Everyone on the mailing list is sent a message
55 automatically by CVS whenever someone checks in a change, this helps
56 to keep track of what's going on when several people are working on
57 related stuff. Ask the CVS meister to put you on the relevant
60 * Create a .cvsrc file. Mine looks like this:
67 It just gives default flags for some of the CVS commands. For instance,
68 the -P flag to 'checkout' says prune empty directories, which is
69 normally what you want.
71 * Check out your sources. The Approved Way (at least by me) to do
74 $ CVSROOT=/local/fp/src/cvsroot
77 or, if you're using csh or tcsh:
78 $ setenv CVSROOT=/local/fp/src/cvsroot
80 $ cvs checkout fpconfig
82 At this point you have a new directory called 'fptools' which contains
83 the basic stuff for the fptools suite - including the configuration
84 files and literate programming tools.
86 $ mv fptools <directory>
88 You can call the fptools directory whatever you like, CVS won't mind.
91 $ cvs checkout ghc hslibs happy
93 The second command here checks out the relevant modules you want to
94 work on. For a GHC build, for instance, you need at least ghc and
97 * Build the software, if necessary. Unless you're just working on
98 documentation, you'll probably want to build the software in order
99 to test any changes you make. For GHC, instructions can be found
100 in the GHC installation guide, online in info format.
102 * Make changes. Preferably small ones first.
104 * Test them. You can see exactly what changes you've made by using
105 the 'cvs diff' command. For example,
109 lists all the changes (using the 'diff' command) in and below the
110 current directory. In emacs, C-c C-v C-= runs 'cvs diff' on the current
111 buffer and shows you the results.
113 * Before checking in a change, you need to update your source tree:
118 This pulls in any changes that other people have made, and merges them
119 with yours. If there are any conflicts, CVS will tell you, and you'll
120 have to resolve them before you can check your changes in. The
121 documentation describes what to do in the event of a conflict.
123 It's not always necessary to do a full cvs update before checking in
124 a change, since CVS will always tell you if you try to check in a file
125 that someone else has changed. However, you should still update
126 at regular intervals to avoid making changes that don't work in
127 conjuction with changes that someone else made. Keeping an eye on
128 what goes by on the mailing list can help here.
130 * When you're happy that your change isn't going to break anything,
131 check it in. For a one-file change:
133 $ cvs commit <filename>
135 CVS will then pop up an editor for you to enter a "commit message",
136 this is just a short description of what your change does, and will
137 be kept in the history of the file.
139 If you're using emacs, simply load up the file into a buffer and type
140 C-x C-q, and emacs will prompt for a commit message and then check in
143 For a multiple-file change, things are a bit trickier. There are
144 several ways to do this, but this is the way I find easiest.
145 First type the commit message into a temporary file. Then either
147 $ cvs commit -F <commit-message> <file_1> .... <file_n>
149 or, if nothing else has changed in this part of the source tree,
151 $ cvs commit -F <commit-message> <directory>
153 where <directory> is a common parent directory for all your changes,
154 and <commit-message> is the name of the file containing the commit
157 Shortly afterwards, you'll get some mail from the relevant mailing
158 list saying which files changed, and giving the commit message.
159 For a multiple-file change, you should still get only *one* message.
161 * As a general rule: commit changes in small units, preferably
162 addressing one issue or implementing a single feature. Provide a
163 descriptive log message so that the repository records exactly which
164 changes were required to implement a given feature/fix a bug. I've
165 found this *very* useful in the past for finding out when a particular
166 bug was introduced: you can just wind back the CVS tree until
169 * Keep the sources at least *buildable* at any given time. No
170 doubt bugs will creep in, but it's quite easy to ensure that any
171 change made at least leaves the tree in a buildable state. We do
172 nightly builds of GHC to keep an eye on what things work/don't work
173 each day and how we're doing in relation to previous verions. This
174 idea is truely wrecked if the compiler won't build in the first place!
176 Ok, that'll do for now.
178 Simon Marlow <simonm@dcs.gla.ac.uk>