Including notes about using 'diff'

README.org

@@ -17,7 +17,7 @@ opportunity to learn about computers, files, directories and programs.
 
 ** Appearance, screens
 
- * [[./tutorial/i3wm_screens.org][~xrandr~: working with two screens in i3-wm]]
+ * [[./tutorial/i3wm_screens.org][xrandr: working with two screens in i3-wm]]
 
 ** Manuals, documentation
 
@@ -33,6 +33,7 @@ opportunity to learn about computers, files, directories and programs.
  * [[./tutorial/display_files.org][Display files: 'less', 'head' and 'tail' commands]]
  * [[./tutorial/files_directories.org][Learning about files and directories]]
  * [[./tutorial/search_files.org][Searching for files in the system]]
+ * [[./tutorial/diff.org][Comparing two files or directories]]
  * [[./tutorial/dd_command_flash_usb.org][Using dd command to flash usb]]
  * [[./tutorial/compress_pdf.org][Compress a pdf file]]
  * [[./tutorial/luakit.org][Searching and editing configuration files]]

tutorial/diff.org

@@ -0,0 +1,33 @@
+#+options: toc:nil num:nil
+
+* Comparing the content of two files or directories
+
+~diff~ is a command line utility used to compare two files or directories
+
+** Compare files
+
+To compare the content of two files use something like
+
+#+begin_example bash
+  diff file1.txt file2.txt  
+#+end_example
+
+You can redirect the output to a file and make a patch: a file containing the differences between both files
+
+#+begin_example bash
+  diff file1.txt file2.txt  patch.txt 
+#+end_example
+
+
+
+** Comparing directories
+
+
+Some arguments may be hepful to have an output showing the differences between two directories:
+~--brief~ (show only the differences) and ~-r~ (compare the directories that are located within the main directory also) 
+
+#+begin_example bash
+  diff --brief -r directory1 directory2
+#+end_example
+
+