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Supplemental Reading Materials
- Explain: df
- Command that shows the available disk space on a system
- Explain: du
- Command that displays the amount of disk space in use.
- Explain: inode
- An inode (index node) stores information about files and folders such as: permissions, ownership, and filetype. Most file systems contain a max number of inodes that it can contain.
- Explain: fsck
- File system check utility. Can be invoked via bash and configured in /etx/fstab. Devices must be unmounted before a check can run.
- Explain: e2fsck
- File system check utility for ext2,3,4 fulesystems. can be used to replay the filesystems journal.
- Explain: make2fs
- Utility for creating new ext2, ext3 or ex4 file systems.
- Explain tune2fs
- Utility used to adjust parameters on an ext2,3,4 filesystem.
- Explain: xfs_repair
- Utility used to repair XFS filesystems.
- Explain: xfs_fsr
- Reorganizes data stored in blocks on an XFS File system. Similar to running a defrag utility on an MS Windows File system.
- Explain: xfs_db
- Utility used to debug an XFS filesystem.
- Explain: mount
- Command used to mount a file system to a mount point ( directory)
- Explain: umount
- Command used to unmount a file system. can specify either a device, label, or mount point.
- Explain: /etc/fstab
- The Filesystem table file. Permanent mount configurations are set here.
- How does mounting work?
- Disk partitions (ships) are mounted to folders (ports) allowing data (Shipping Goods) to be added to that port.
- How do octal permissions work?
- Octal permissions are basically numeric permissions that represent what a user can and cant do. 4 is read, 2 is write, 1 is execute 5 is read+execute, 2 is write and execute…etcetc 4,2,1 just memorize that when doing an ls -lah
- Explain: chmod
- Change the mode of a file or directory, which will effect the items permissions.
- Explain: chgrp
- Change the group ownership of a file or folder.
- Explain: SUID
- “Set User ID”. Files with an “s” instead of an “x” within the user column have this set. Note that this will not work on bash scripts anymore. Also, many file systems can be mounted with the “nosuid” option.
- Explain: SGID
- “Set Group ID” bit. Files and folders with the ‘s’ in place of the ‘x’ permission within the groups columns have this set. This assigns group ownership to files. Useful for shared group directories.
- Explain: Sticky Bit.
- The permission has a ‘t’ in place of an ‘x’ in the other’s column. This permission only allows the creator of a file to remove the file.
- Explain: umask
- Shows the current umask settings. Can alos be used to set a new umask value for the current shell session
- What are the default permissions for directories and files?
- Explain: umask value
- Subtract the umask value from the default permissionto get the currently configured permission value.