1. Concurrent Version System (CVS)
Doris Lee
12/1/2018

2. Agenda Introduction Useful Commands Tagging and Branching Case Studies
Do and Don’t
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3. What is CVS? Why we need CVS? Dominant version control system
Time machine
Why we need CVS?
Create a repository
To coordinate code
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4. Introduction
Setup : download software and set the environment variables
CVSROOT
CVS_RSH
Files in the repository
All program source files
All non-code project artifacts
Exclude files that can be reconstituted easily
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5. Introduction (Cont’d)
Keyword e.g. $Author$, $Name$, $Date$
$Author$ $Author : ywlee$
Created “CVS” Subdirectory
Keyword – metadata about latest revision of file
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6. Useful Commands Command Usage: checkout - retrieve file(s)
cvs [cvs-options] command [command-options-and-arguments]
checkout - retrieve file(s)
add - add file(s) to repository
update - download changes
commit - upload changes
diff - view differences
log - display log info
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7. Note Binary file NO way to delete directories in CVS !
“cvs add TextFile” vs “cvs add -kb BinaryFile”
NO way to delete directories in CVS !
Sticky Bit - when checkout old version of file
impact : can’t overwrite current version at repository
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8. Tagging Marking a group of file revisions cvs tag Rel_1_beta
File1.java
Ver 1.1
Ver 1.2
Ver 1.3
File2.java
Ver 1.1 :
Ver 2.1
Ver 2.2
File3.java
Ver 1.1
Ver 1.2
At a particular point of time
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9. Branching Branch : a fork of the repository
experimental work, release, or bug fixing
cvs rtag –b BR_1 projectName
BR_1
Trunk
2.5
2.6
2.7
2.8
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10. Case Study (1) 4 2 3 1 Alan Mary cvs update cvs commit cvs update
Test.java revision 1.1 :
Total+=amount;
Test.java revision 1.1 :
Total+=amount;
if (amount > 10) {
Total+=amount; } :
- new revision: 1.2
done
Total++; 3 1
- Merging differences between 1.1 and 1.2 into Test.java
- new revision: 1.3
done
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Alan
Mary

11. Case Study (2) 4 2 3 1 Mary Alan cvs update cvs commit cvs update
Test.java revision 1.1 :
Total+=amount;
Test.java revision 1.1 :
Total+=amount;
Total+=subtotal;
Total+=tax;
- new revision: 1.2
done 3 1
- Merging differences between 1.1 and 1.2 into Test.java
- rcsmerge: warning: conflicts during merge
- cvs update:conflicts found
Mary
Alan
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12. Case Study (2) (cont’d) Resolve conflicts by communications, and
I) if the repository is the correct one,
Remove local copy and do update
II) if different codes are preferred,
Edit the code
<<<<<< Test.java
Total+=subtotal;
=========
Total+=tax;
>>>>>>
III) cvs commit
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13. Case Study (3) ! Test.txt(repository) Test.txt(sandbox) Blue Blue
Yellow
Orange !
Test.txt(sandbox)
Blue
Yellow
Orange
cvs diff
Why?
Tab and Spaces are different in CVS!
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14. Do and Don’t Do Don’t Check in only when files are stable
Enter meaningful comments
Check in only when files are stable
“cvs update” before “cvs commit”
Don’t
Change files in the ‘CVS’ subdirectory
Change or create files in repository directly
Change layout of a shared file
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15. References Books : Online :
Pragmatic Version Control Using CVS by David Thomas
Essential CVS by Jennifer Vesperman
Online :
CSC207, CSC408 websites
man pages
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16. Question and Answer
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