Operating Systems I

1. Operating Systems I Using Text Editors

2. Primary Learning Objective Manipulate Text Files Using Built-in Text Editors

3. Specific Learning Objectives • Identify and define the key terms used with text editors • Use text editors built into the operating system to create text files • Create a text file using the COPY CON command • View a text file using the TYPE command • Use redirection operators in CLI

4. Text Files • Letters and simple punctuation that makes up words, sentences, and paragraphs. • Typically in IT, the term text refers to text stored as ASCII code (that is, without any formatting). • Objects that are not text include graphics, numbers (if they're not stored as ASCII characters, and program code.

5. ASCII • Stands for American Standard Code for Information Interchange • The original standard ASCII coding scheme used 7 bits (128 characters) to represent all upper &lower case letters, 0-9, punctuation, and special control characters (See page 97) • Extended ASCII uses 8 bits (256 characters) added foreign-language, graphical & scientific characters. ( É, û, ß, µ)

6. Other Character Sets • EBCDIC (pronounced "ehb-suh-dik" ) is a binary code for alphabetic and numeric characters that IBM developed for its larger operating systems. • ANSI’s first 128 characters are the same as ASCII but the second 128 depends are the language supported • Unicode uses 16 bits (65,536 characters) of which about 21,000 are Chinese ideographs

7. Built-In Text Editors • Notepad – Create or edit text files without formatting. Used for batch files, in coding HTML and other programming languages. • MS-DOS Editor – Create or edit files using the EDIT.COM command (actually a small application). Uses similar to Notepad. • COPY CON – Create but not edit small files. • WordPad – Like MS Word it uses formatting so the actual file size will be larger.

8. Viewing Text Files from CLI • Use MS-DOS Editor • Use the TYPE command

9. Using Redirection Operators • In CLI, the OS expects input from the standard input device or keyboard and sends or directs output to the standard output device or monitor. • To send output or input to/from a device other than the standard one, you redirect or change the destination/source with redirection operators • Some of the redirection operators are output ( > ), input ( < ), pipe ( | ), and appending ( >> )

10. Output & Appending Redirection Operators • Output is the greater than symbol ( > ) • If you want to redirect output to a file/printer, specify the name of the file or printer after the symbol. If the filename exists, the file will be overwritten. dir > filename dir > prn • To append, to add to an existing file use ( >> ). date >> filename

11. Input Redirection Operator • Although the OS expects the input to come from the keyboard, it can come from a file instead. • Input is the less than symbol ( < ) • If you want to redirect input to a process or command, specify the name of the file or printer after the symbol. Command < filename DEL One\*.* < y.txt

12. Piping Output to the MORE Filter • A filter is a command that can modify the output of another command. The MORE filter or command is an external command that displays a screen of output, pauses, and then displays “—More—” which permits you to continue when ready. • The pipe operator ( | ) redirects the output produced by one command so that the output then becomes the input for another command. [command] | MORE TYPE syllabus.txt |MORE

13. Summary • Text Files • ASCII and other character sets • Built-In Text Editors • Viewing Text Files from CLI • Redirection Operators

14. Homework Assignment • Reading • Windows XP Textbook – pp 86-87 • CLI Textbook - pp. 96-107, 114-116 • Lab Exercise 7: Text Files • Due Date: A Week from Next Tuesday