011300 Intro To Dos
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This document provides an overview of the Disk Operating System (DOS) including its key components, file naming conventions, file attributes, commands, and batch files. It discusses the kernel, file allocation table (FAT), short and long filenames, wildcards, CONFIG.SYS, AUTOEXEC.BAT, internal vs external commands, redirection, and common DOS commands for directories, disks, and batch files.
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011300 Intro To Dos
- 1. Introduction to DOS CTIN January 13, 2000 Sandy Bacik, Senior Security Consultant Breakwater Security Associates
- 2. Agenda What is DOS Filenames Files DOS Overview Sample Batch File
- 3. What is an operating system? It manages an environment that contains working programs and grunt workers supplying subtasks, when requested to perform an action.
- 4. DOS D isk O perating S ystem An operating system that deals with hard disks. DOS worries about how files are stored and how to access them.
- 5. Pieces of DOS Kernel: Command Processor: IO.SYS, MSDOS.SYS, DBLSPACE.BIN, DRVSPACE.BIN COMMAND.COM
- 6. Key files to DOS IO.SYS MSDOS.SYS COMMAND.COM
- 7. FAT File Allocation Table This tracks what is using what portions of the hard disk. There are actually 2 copies of FAT for each logical drive.
- 8. File Names Short Filename (SFN) 8.3 Standard - (8 characters).(3 characters) Characters were upper case A-Z, numbers 0-9 and any of the following symbols($ % ‘ _ @ ~ ` ! ( ) { } ^ # &)
- 9. File Names Long Filename (LFN) Update 254 characters, including the path name Includes the above characters plus + , ; = [ ] and lower case a-z
- 10. Long Filenames to Short Filenames (1) No 2 files can have the same LFN and/or SFN If the LFN fits the SFN standard, the LFN and the SFN are the same.
- 11. Long Filenames to Short Filenames (2) If the LFN does not fit the SFN standard, then All spaces are stripped from the name Upper cases what remains Uses the first 8 characters of the name and first 3 characters following the first dot (.) If the SFN exists, then the last 2 or more characters are lopped off, substituting a tilde (~) and a sequential 1, 2 or more digit number
- 12. Long / Short Filename (1)
- 13. Long / Short Filename (2)
- 14. Long / Short Filename (3)
- 15. File Types ASCII or plain text files Binary files, non-human readable Word processing files Databases and spreadsheets Program files Sound or image files
- 16. Deleting a File - What Happens? The data is not erased from your disk. 1. 0 is placed in all the cluster locations in the FAT that belong to that file. 2. It changes the very first entry in the directory entry from ASCII to the special value E5h, digital value 229, and extended ASCII value lower case sigma.
- 17. Wildcards ? (question mark) Any character can go in that location * (asterisk or star) Any group of characters can go in that location
- 18. CONFIG.SYS Executed by MSDOS.SYS upon system boot It lets the system know how many files can be opened at one time It contains instructions to load device drivers
- 19. AUTOEXEC.BAT Executed by COMMAND.COM upon system boot A series of DOS batch file commands created by the user to be executed each time the PC is turned on or rebooted
- 20. Files A place to store data Directories A place to store files
- 21. 6 File Attributes Read-only Hidden System Volume Label Subdirectory Archive
- 22. Pathname A sequence of directory names followed by a file name. Path Similar to a pathname, but does not contain the file name.
- 23. Parent Directory Any directory that contains subdirectories
- 24. Internal Commands Commands which reside in memory Part of COMMAND.COM Simplest and most commonly used commands For example: DEL MKDIR PATH REM DIR SET TIME COPY CHDIR VOL IF GOTO
- 25. External Commands Commands ending with .COM, .EXE, or .BAT Precedence order: .COM, .EXE, .BAT Do not need the extension to execute For example: APPEND FDISK FIND FORMAT ATTRIB SORT LABEL PRINT XCOPY
- 26. Redirection >> Append > Write, starting at the beginning | Pipe to something, write < Input to
- 27. Getting Command Help HELP <command> <command> /?
- 28. Sample Commands - Directories MKDIR CHDIR or CD RMDIR
- 29. Top 10 DOS Commands CD DIR MD RD FORMAT COPY DEL UNDELETE TYPE CTRL-BRK
- 30. DOS File Commands ATTRIB COPY DEL DIR FC MOVE RENAME REPLACE TYPE UNDELETE VERIFY
- 31. DOS Floppy Disk Commands CHKDSK DISKCOMP DISKCOPY FORMAT LABEL SYS UNDELETE UNFORMAT VOL
- 32. DOS Hard Disk Commands (1) APPEND CD DBLSPACE DBLSPACE.SYS DEFRAG DELTREE FDISK MD MOVE
- 33. DOS Hard Disk Commands (2) MSBACKUP PATH PROMPT RD REPLACE RESTORE SHARE SUBST TREE
- 34. 6 Points of a Batch File Pure ASCII text file Must end with .BAT To stop use CTRL-C or CTRL-BRK Simple list of command Virtually all DOS commands can be used DO NOT RELY on the DOS manual
- 35. DOS Batch File Commands CALL CHOICE ECHO ERRORLEVEL FOR..IN..DO GOTO IF/IF NOT PAUSE REM %0-%9, %var% SHIFT
- 36. Questions?
- 37. Thank you Contact: Sandy Bacik email: [email protected] phone: 253-661-9327
Editor's Notes
- #2: We are going to review the simple things of how the boot process works and what is actually happening with the box, then review how a hard disk drive is setup and how it works, then we will begin to get into how the DOS operating system works. In a later sessions we will be reviewing DOS commands and what we can do with them.