Creating Source File Patches

When changing source files outside of using configuration management, it's important to produce a patch file to enable others to easily view and re-create your changes from the original source file.

Syntax

Using the Linux 'diff' command, you can produce a difference between the original (from file), and the new (to file).

  $ diff -u original.cpp newversion.cpp > original.patch

Example

In the following output, you see the difference between the original (from file), and the new (to file). The output highlights lines to be removed with '---' and lines to be added with '+++'

$ diff -u bonnie++-1.03e/bon_time.cpp bon_time.cpp 
--- bonnie++-1.03e/bon_time.cpp	2003-01-08 17:39:12.000000000 -0500
+++ bon_time.cpp	2009-06-03 17:10:49.000000000 -0400
@@ -159,10 +159,10 @@
   if(m_delta[test].Elapsed < MinTime)
   {
     if(m_type == txt)
+    {
       fprintf(m_fp, " +++");
-    else
-      fprintf(m_fp, ",+++");
-    return 0;
+      return 0;
+    }
   }
   int cpu = int(m_delta[test].CPU / m_delta[test].Elapsed * 100.0);
   if(m_type == txt)
@@ -181,12 +181,10 @@
     else
       fprintf(m_fp, ",");
   }
-  else if(m_delta[test].Elapsed < MinTime)
+  else if(m_delta[test].Elapsed < MinTime && m_type==txt)
   {
     if(m_type == txt)
       fprintf(m_fp, " +++++");
-    else
-      fprintf(m_fp, ",+++++");
   }
   else
   {
@@ -224,12 +222,10 @@
     else
       fprintf(m_fp, ",");
   }
-  else if(m_delta[test].Elapsed < MinTime)
+  else if(m_delta[test].Elapsed < MinTime && m_type == txt)
   {
     if(m_type == txt)
       fprintf(m_fp, " +++++");
-    else
-      fprintf(m_fp, ",+++++");
   }
   else
   {

Applying Patches

$ patch < original.patch