1. Chapter Five Advanced File Processing Guide To UNIX Using Linux Fourth Edition Chapter 5 Unix (34 slides)1 CTEC 110

2. Use the pipe operator to redirect the output of one command to another command Use the grep command to search for a specified pattern in a file Use the uniq command to remove duplicate lines from a file Use the comm and diff commands to compare two files Use the wc command to count words, characters and lines in a file Objectives Chapter 5 Unix (34 slides)2 CTEC 110

3. Use manipulation and transformation commands, which include sed, tr, and pr Design a new file-processing application by creating, testing, and running shell scripts Objectives (continued) Chapter 5 Unix (34 slides)3 CTEC 110

4. Selection commands focus on extracting specific information from files Advancing Your File-Processing Skills Chapter 5 Unix (34 slides)4 CTEC 110

5. Manipulation and transformation commands alter and transform extracted information into useful and appealing formats Chapter 5 Unix (34 slides)5 CTEC 110 Advancing Your File-Processing Skills (continued)

6. Chapter 5 Unix (34 slides)6 CTEC 110 Advancing Your File-Processing Skills (continued)

7. Using the Pipe Operator – The pipe operator (|) redirects the output of one command to the input of another –An example would be to redirect the output of the ls command to the more command –The pipe operator can connect several commands on the same command line Using the Selection Commands Chapter 5 Unix (34 slides)7 CTEC 110

8. Using the Pipe Operator Chapter 5 Unix (34 slides)8 CTEC 110 Using pipe operators and connecting commands is useful when viewing directory information

9. Used to search for a specific pattern in a file, such as a word or phrase grep’s options and wildcard support allow for powerful search operations You can increase grep’s usefulness by combining with other commands, such as head or tail Using the grep Command Chapter 5 Unix (34 slides)9 CTEC 110

10. Removes duplicate lines from a file Compares only consecutive lines, therefore uniq requires sorted input uniq has an option that allows you to generate output that contains a copy of each line that has a duplicate Using the uniq Command Chapter 5 Unix (34 slides)10 CTEC 110

11. Using the uniq Command (continued) Chapter 5 Unix (34 slides)11 CTEC 110

12. Using the uniq Command (continued) Chapter 5 Unix (34 slides)12 CTEC 110

13. Used to identify duplicate lines in sorted files Unlike uniq, it does not remove duplicates, and it works with two files rather than one It compares lines common to file1 and file2, and produces three column output –Column one contains lines found only in file1 –Column two contains lines found only in file2 –Column three contains lines found in both files Using the comm Command Chapter 5 Unix (34 slides)13 CTEC 110

14. Attempts to determine the minimal changes needed to convert file1 to file2 The output displays the line(s) that differ Codes in the output indicate that in order for the files to match, specific lines must be added or deleted Using the diff Command Chapter 5 Unix (34 slides)14 CTEC 110

15. Used to count the number of lines, words, and bytes or characters in text files You may specify all three options in one issuance of the command If you don’t specify any options, you see counts of lines, words, and characters (in that order) Using the wc Command Chapter 5 Unix (34 slides)15 CTEC 110

16. Using the wc Command (continued) Chapter 5 Unix (34 slides)16 CTEC 110 The options for the wc command: –l for lines –w for words –c for characters

17. These commands are: sed, tr, pr Used to edit and transform the appearance of data before it is displayed or printed Using Manipulation and Transformation Commands Chapter 5 Unix (34 slides)17 CTEC 110

18. sed is a UNIX/Linux editor that allows you to make global changes to large files Minimum requirements are an input file and a command that lets sed know what actions to apply to the file sed commands have two general forms –Specify an editing command on the command line –Specify a script file containing sed commands Introducing the sed Command Chapter 5 Unix (34 slides)18 CTEC 110

19. tr copies data from the standard input to the standard output, substituting or deleting characters specified by options and patterns The patterns are strings and the strings are sets of characters A popular use of tr is converting lowercase characters to uppercase Translating Characters Using the tr Command Chapter 5 Unix (34 slides)19 CTEC 110

20. pr prints specified files on the standard output in paginated form By default, pr formats the specified files into single- column pages of 66 lines Each page has a five-line header containing the file name, its latest modification date, and current page, and a five-line trailer consisting of blank lines Using the pr Command to Format Your Output Chapter 5 Unix (34 slides)20 CTEC 110

21. The most important phase in developing a new application is the design The design defines the information an application needs to produce The design also defines how to organize this information into files, records, and fields, which are called logical structures Designing a New File-Processing Application Chapter 5 Unix (34 slides)21 CTEC 110

22. The first task is to define the fields in the records and produce a record layout A record layout identifies each field by name and data type (numeric or nonnumeric) Design the file record to store only those fields relevant to the record’s primary purpose Designing Records Chapter 5 Unix (34 slides)22 CTEC 110

23. Multiple files are joined by a key: a common field that each of the linked files share Another important task in the design phase is to plan a way to join the files The flexibility to gather information from multiple files comprised of simple, short records is the essence of a relational database system Linking Files with Keys Chapter 5 Unix (34 slides)23 CTEC 110

24. Chapter 5 Unix (34 slides)24 CTEC 110

25. With the basic design complete, you now implement your application design UNIX/Linux file processing predominantly uses flat files Working with these files is easy, because you can create and manipulate them with text editors like vi and Emacs Creating the Programmer and Project Files Chapter 5 Unix (34 slides)25 CTEC 110

26. Creating the Programmer and Project Files (continued) Chapter 5 Unix (34 slides)26 CTEC 110

27. The awk command is used to prepare formatted output For the purposes of developing a new file- processing application, we will focus primarily on the printf action of the awk command Formatting Output Chapter 5 Unix (34 slides)27 CTEC 110 Awk provides a shortcut to other UNIX/Linux commands

28. Shell scripts should contain: –The commands to execute –Comments to identify and explain the script so that users or programmers other than the author can understand how it works Use the pound (#) character to mark comments in a script file Using a Shell Script to Implement the Application Chapter 5 Unix (34 slides)28 CTEC 110

29. You can run a shell script in virtually any shell that you have on your system The Bash shell accepts more variations in command structures that other shells Run the script by typing sh followed by the name of the script, or make the script executable and type./ prior to the script name Running a Shell Script Chapter 5 Unix (34 slides)29 CTEC 110

30. An effective way to develop applications is to combine many small scripts in a larger script file Have the last script added to the larger script print a report indicating script functions and results Putting it All Together to Produce the Report Chapter 5 Unix (34 slides)30 CTEC 110

31. UNIX/Linux file-processing commands are (1) selection and (2) manipulation and transformation commands uniq removes duplicate lines from a sorted file comm compares lines common to file1 and file2 diff tries to determine the minimal set of changes needed to convert file1 into file2 Chapter Summary Chapter 5 Unix (34 slides)31 CTEC 110

32. tr copies data read from the standard input to the standard output, substituting or deleting characters specified sed is a file editor designed to make global changes to large files pr prints the standard output in pages Chapter Summary (continued) Chapter 5 Unix (34 slides)32 CTEC 110

33. The design of a file-processing application reflects what the application needs to produce Use record layout to identify each field by name and data type Shell scripts should contain commands to execute programs and comments to identify and explain the programs Chapter Summary (continued) Chapter 5 Unix (34 slides)33 CTEC 110

34. Work through Hands-on Projects at end of chapter 5 Canvas: Review Questions 5 –(Do not do questions 22,23,24 and 25) Quiz 5 Unix… Chapter 5 Unix Exercises Chapter 5 Unix (34 slides)34 CTEC 110