CIS 225

File System Management

Disk Partitions

• Logical subdivision of a physical disk
• Has a file format, stores files
• Each drive can have multiple partitions
• Each operating system requires a separate partition

Partition Styles

• Master Boot Record (MBR)
  • Partition Table
  • 4 primary partitions or
    3 primary + 1 extended
  • BIOS for booting
• GUID Partition Table (GPT)
  • Partition data within partitions
  • Redundant backup tables
  • EFI for booting

Bootloader

• BIOS
  • Uses MBR disks for booting
  • Master boot code in 1st sector
• EFI
  • Uses GPT disks for booting
  • ESP (EFI System Partition) & MSR (Microsoft Reserved) partition required

Basic vs. Dynamic

• Basic
  • Drives correspond to partitions
  • Cannot modify on the fly
• Dynamic
  • Allows spanning & RAID
  • Can modify on the fly (somewhat)

Windows Formats

• FAT/FAT32
  • File Allocation Table
  • FAT: <4GB; FAT32: <32GB
  • Simple Access Controls
• NTFS
  • New Technology File System
  • File info stored as Database
  • Advanced Access Controls

Linux Formats

• exFAT
  • File Allocation Table
  • Similar to Windows FAT32
• ext3/ext4
  • Extended File System
  • Up to 1 Exbibyte (~10¹⁸ bytes)
  • Journals Protect Against Crashes

File Permissions

• Determines which users can read/write files or folders
• Based on user and group memberships and file settings
• Helps prevent unwanted access to files

Windows Permissions

• Full Control - Can take ownership & change permissions
• Modify - Read/Write/Change/Delete
• Read & Execute
• List Folder Contents - Folders Only
• Read - Access files
• Write - Modify files

Ubuntu Permissions

• 3 classes: User, Group, Others
• 3 rights:
  • Read - Can read contents
  • Write - Can create/modify/delete
  • Execute - Can run programs/scripts

Modifying Ubuntu Permissions

• chmod - Change permissions
  • chmod [class][op][mode] file/folder
  • chmod [octal_mode] filename/folder
• chown - Change User/Group (sudo)
  • chown [user]:[group] filename/folder
• chgrp - Change Group (must own file)
  • chgrp [group] filename/folder

Ubuntu Permission Example

• Users: acct, hr, user, guest, root
• /files: All users except guest should have rwx, guest r only
• /files/acctg: acct should have rwx, hr should have r, all else no access
• /files/hr: hr and acct should have rwx, user should have rx, all else no access

Ubuntu Permission Example

• group1: acct, hr, user
• group2: acct, hr
• group3: hr


• /files: root:group1 rwxrwxr__
• /files/acctg: acct:group3 rwxr_____
• /files/hr: user:group2 r_xrwx___

Reading

http://people.cis.ksu.edu/~russfeld/cis225fall2015/

Assignments

• Lab 3 - User Accounts & File Systems
  Due 9/28 11:30 AM Before Lecture!!