Chapter Eight

1. Chapter Eight Exploring the UNIX Utilities

2. Lesson A Using the UNIX Utilities

3. Objectives • Understand what UNIX utilities are available and the classifications of utilities • Make a bootable floppy disk to boot the system in case of an emergency • Duplicate files on a floppy disk

4. Objectives • Determine hard disk usage and available free space • Locate and remove unnecessary files from the hard disk • Display the CPU status and internal memory usage

5. Understanding UNIX Utilities • UNIX utilities let you create and manage files, run programs, produce reports, and generally interact with the system • They also offer a full range of services that let you monitor and maintain the system and recover from a wide range of errors • Utility programs are vital for working through an OS and new utilities are continually being added in order to make UNIX run more efficiently

6. Understanding UNIX Utilities • UNIX utilities are classified into seven major function areas dictated by user needs • File processing • System status • Networking • Communications • Programming • Source code management • Miscellaneous

15. Using theFile Processing Utilities • The dd command allows you to copy a file and change the format of the destination file • The dd command possesses a rich set of options that allow it to handle copies when other methods are inappropriate • An advantage to using the dd command over cp is that all users, not just the administrator, can copy files to and from the floppy drive

16. Making a Bootable Floppy Disk • It is a good idea to make a bootable floppy disk, because a computer problem may prevent you from starting UNIX from the system • To make a bootable floppy disk, use four utility programs: rdev, mkfs, fdformat, dd

17. Making a Bootable Floppy Disk • The rdev command queries and sets the root device, which is the hard disk partition that houses UNIX’s root file system • The mkfs command builds a UNIX or Linux file system on a device such as a floppy disk or a hard disk partition • The fdformat command formats a floppy at low levels to ensure the media is clear of defects and is writeable • Use the dd command to make a back-up copy of a floppy disk

18. Making a Bootable Floppy Disk The file system type determines how UNIX reads and writes information from or onto the device

19. Making a Bootable Floppy Disk After creating a bootable disk, it can be used to start the system

20. Checking Hard Disk Usage • To maintain adequate hard disk free space, use these strategies: • Be vigilant against running dangerously low on free space by using the df command • Watch for conspicuous consumption using the du command • Follow a routine schedule for “garbage” collection and removal by using the rm command

21. Using the df Utility The df utility reports on the status of1024-byte blocks

22. Using the df Utility The df –h option causes the block data to display in human-readable form

23. Using the df Utility The du utility summarizes disk usage, expressed in 512-byte blocks (default) or by the number of bytes(-b option)

24. Using the df Utility ...the second screen resulting from using | more

25. Removing Garbage Files • Garbage files are temporary files that lose their usefulness after several days • Two examples of garbage files are core files (named core) and a.out files • Use the find command to assist you in locating these files and the rm command to remove them

26. Applying System Status Utilities • System engineers primarily use the data related to system status • One of the most effective utilities for auditing system performance is the top command • The top command displays a listing of the most CPU-intensive tasks, such as the processor state

27. Applying System Status Utilities The top utility run without any options specified

28. Applying System Status Utilities To kill the top utility process, enter k and specify the PID to terminate

29. Applying System Status Utilities You cannot killthe top utility when run in secure mode

31. Applying System Status Utilities The free utility displays the amount of free and used memory in the system

32. Applying System Status Utilities The ps command shows a list of processes associated with the current login session that are currently running

33. Applying System Status Utilities The ps command with the –A option shows a list of all system processes currently running

34. Lesson B Working with the Text-Formatting File Utilities

35. Objectives • Check the spelling of text in a document • Use the cmp command to compare the contents of two files • Format text to create a man page • Use the groff utility to test a man page you have created • Use the man utility to view a man page you have created

36. Checking the Spellingof a Document Ispell scans a document, displays errors on the screen and suggests alternative spellings

37. Comparing Files • Use the cmp utility to compare the contents of two files, and report the first difference between them • The cmp command displays the character position and line number of this difference • If there are no differences, the cmp command displays nothing

38. Formatting Text in UNIX • Text formatting in UNIX involves preparing a text file with embedded typesetting commands and then processing the marked-up text file with a computer program • UNIX’s nroff and troff commands are often used to process the embedded typesetting commands to format the output • An embedded code is a special sequence of characters that is included with the regular text of the file

39. Formatting Text in UNIX Linux introduced groff, which implements the features of both nroff and troff

40. Formatting Text in UNIX Groff can be used to produce a man page that contains the standard man page sections

41. Formatting Text in UNIX Man pages are made available to others by having a supervisor user copy it to one of the man page directories

42. Chapter Summary • UNIX utilities are classified into seven major functional areas dictated by user needs: file processing, networking, communications, system status, programming, source code, management, and miscellaneous tasks • Utility programs are distinguished from other OS programs, because they are add-ons and not a part of the UNIX shells • Because utility programs are executed by entering names on the command line, they are commonly referred to as commands

43. Chapter Summary • The dd command possesses a rich set of options that allow it to handle copies when other copying methods fail • To make a bootable floppy disk, use four utility programs: rdev, mkfs, fdformat, and dd • The rdev command queries and sets the root device • The fdformat command performs a low-level format on a floppy disk • The mkfs utility sets up a file system

44. Chapter Summary • The df utility checks and reports on free disk space • The du command checks for disk usage • Use the find command to retrieve wasteful files and then use the rm command to remove them • The top and free utilities provide detailed views of the “internals” of the system • Redirect output of the top and free commands to a disk file to use as input for a report to the system administrator

45. Chapter Summary • Run a program in the background by appending the & operator to the end of a command line • The ps command displays all processes currently running • The kill command terminates a specific process • The utility that checks spelling, ispell, scans a document for typing errors

46. Chapter Summary • Text formatting involves embedding typesetting commands in a file, and then processing the the marked-up file with a program that generates commands for the output device • The text containing the embedded typesetting commands is processed by a program like nroff and troff that formats the output • Linux introduced groff, which implements the features of both nroff anf troff • Those who have supervisor privileges most often create man pages