handout_4a.txt

CS 35L Software Construction Laboratory (Lab4-A)
Mon, April 23, 2012, Ver 1.2

Command "diff"
  compare files line by line

  diff helps you to find the difference between two files.
    - Source code versioning
    - Compare similar files

  diff file_1 file_2
    Note: without any option, diff will give you normal outut
          a stands for added, d for deleted and c for changed

  diff -u file_1 file_2
    Note: with -u option, you will get unified format output
          Programs using this format: patch, git, svn

  Unified format output (header + hunk)
      header: a diff file starts with two lines describe two files
        --- test	2011-10-17 08:51:11.200077000 -0700
        +++ test2	2011-10-17 08:51:30.086132000 -0700
      hunk: a diff file contains one or more change hunks starting with
        @@ -l,s +l,s @@
      The first pair of l,s is for the origin file, and the second pair for
    the new file. l indicates the start line number while s is the number of 
    lines in the hunk.

  Diff Multiple files
      $ diff <from-folder> <to-folder>

      diff will autodetect the input is a file or a directory. And diff
  each files in the directory
      If you want to diff into subdirectories recursively, you may want to
  use:
      $ diff -r <from-folder> <to-folder>

  More reading: http://en.wikipedia.org/wiki/Diff

Command "patch"
  apply a diff file 

  usage:
     1/  patch [options] [originalfile [patchfile]]
     2/  patch -p0 <patchfile

  -p option
     -p option give patch the clue to figure out what is the filename to
  patch on by indicating the number of "slashes" to ignore in the filenames
     SEE: example1

  Reverse a patch
     $ patch -R < patchfile  

Lab 4 Guideline
    NOTE: Please start to work on the lab part only. Homework is subjest to
          change.
    In this lab, you need to create a patch using git and then apply it to a
  previous version of the source code of diffutil

Software Version Control
  Common features of Revision Control
    1/ roll-back feature. (a snapshot of the source code)
    2/ synchronization between team members
    3/ source code distribution (e.g. github)
    4/ quality assurance (QA) and code review
  More reading: http://en.wikipedia.org/wiki/Revision_control
  
  Two tools we will cover in Thursday: git and subversion (a.k.a. svn)
  git http://en.wikipedia.org/wiki/Git_(software)
  svn http://en.wikipedia.org/wiki/Apache_Subversion