Chapter 2 120G

What is the /lib Directory?

/lib houses: Kernel modules Security information Shared library images Used by programmers to share code rather than creating copies in their programs. Many files in this directory are symbolic links to other library files

What is the The /proc Directory?

/proc occupies no space on the disk Virtual file system allocated in memory only Files in /proc refer to various processes running on the system as well as details about the OS kernel

How is group id (GID) used?

A group id (GID) gives a group of users equal access to files that they all share

What do swap partition do?

Acts like an extension of memory General rule: same size as RAM A swap partition enables virtual memory /boot partition to store OS kernel files Other partitions: /usr (for utilities), /home, /var Mount partition to become part of file system

What does the root file system contain?

All essential programs for file system repair: restoring from a backup, starting the system, and initializing all devices and operating resources. It also contains the information for mounting all other file systems.

/ usage

Any time the / symbol is the first character in a path, it stands for the root file system directory. All other / symbols in a path serve to separate the other names

Where does the treelike structure for UNIX/Linux file systems starts

At the root file system level Root is denoted by / Slash represents the root file system directory

How is Sticky bit: t (used in place of x)?

Before: caused executable program to stay resident in memory after it was exited Now: enables file to be executed, but only the file's owner or root have permission to delete or rename it

What is the /boot Directory contain?

Files needed by the bootstrap loader The bootstrap loader is the utility that starts the OS Kernel (OS) images

How is Set user id (SUID) bit: s (used in place of x)?

Gives current user temporary permissions to execute program-related files as though they are the owner

What is the /root Directory?

Home directory for the root user The system administrator

What is /usr Directory?

Houses software offered to users Software might be: Accounting programs Manufacturing programs Programs for research applications Office software Frequently located on the /usr partition

What is the the pwd command used for?

If you have configured your prompt so that it does not show your working directory, you can use the pwd command (pwd stands for print working directory) to verify in what directory you are located, along with the directory path. pwd prints the working directory Useful for regular users, system administrators, and in scripts

The root (/) file system is mounted by the kernel when the system starts.

To mount a file system is to connect it to the directory tree structure. The system administrator uses the mount command to mount a file system.

What is the cd (change directory)command used for? Syntax cd [directory]

To navigate the UNIX/Linux directory structure directory is the name of the directory to which you want to change. The directory name is expressed as a path to the destination, with slashes (/) separating subdirectory names.

What is an extent use for?

To reduce file fragmentation, because a block of contiguous disk storage can be reserved for a file.

What is cp and rm used for?

Use cp to copy files and rm to delete them

What do you use to specify a file or directory?

Use its pathname, which follows the branches of the file system to the desired file. A forward slash (/) separates each directory name. Ex : /home/jean/source/phones.502

What is mount used for?

Use mount to connect the file system partitions to the directory tree when the system starts Ex. mount -t iso9660 /dev/cdrom /media/cdrom

What can I used the ls command for?

Use the ls (list) command to display a directory's contents, including files and other directories. When you use the ls command with no options or arguments, it displays the names of regular files and directories in your current working directory.

What is umount used for?

Use umount before removing the storage media Ex. umount /media/cdrom

What are permissions?

Users can set permissions for files/directories they own so as to establish security Permissions manage who can read, write, or execute files Original file owner of a file is the account that created it. File ownership can be transferred to another account

How do you change permission on a file?

Using chmod to change permissions of a file Or, use the octal permission format

What are hot fixes?

Which automatically move data on damaged portions of disks to areas that are not damaged

In UNIX/Linux, you can refer to a path as either an absolute path or a relative path. An absolute path is ?

Begins at the root level and lists all subdirectories to the destination file. For example, assume that Becky has a directory named lists located under her home directory. In the lists directory, she has a file called todo. The absolute path to the todo file is /home/becky/lists/todo. This pathname shows each directory that lies in the path to the todo file.

What does the /etc Directory contain?

Configuration files that the system uses when the computer starts.

What is the superblock?

Contains information about the layout of blocks on a specific partition. This information is the key to finding anything on the file system, and it should never change. Without the superblock, the file system cannot be accessed.

What is the command, rmdir used for?

Delete empty directories

What are information nodes, or inodes?

Each directory/file has an inode and is identified by an inode number Inode 0 contains the root of the directory structure (/) Jumping-off point for all other inodes Contains file/directory name, general information, pointer to the directory/file on a disk partition In short, the inode tells the operating system where to find a file on the hard disk.

UNIX/Linux systems support many file systems

Examples: UNIX file system (ufs), extended file system (ext or ext fs)

What is ufs original native UNIX file system?

Expandable, supports large amounts of storage, provides excellent security, reliable Supports journaling Supports hot fixes

Where are files store?

Files are stored in directories in the file system, starting from the root file system directory

What is the /dev Directory?

Files in /dev reference system devices Devices are managed through device special files Contain information about I/O devices that are used by OS kernel when a device is accessed Two types: Block special files Example: for CD/DVD drives Character special files Example: for printers To see the list of device files: ls -l /dev null is a "black hole"

What is /home partition used for?

If you plan to have multiple users access the system which is the home directory for all users' directories. The /home partition is the storage space for all users'work. If the root partition (/)—or any other partition—crashes, having a /home partition ensures that you do not lose all the users' information.

What is a /usr partition used for?

If you plan to have multiple users accessing your system in which to store some or all of the nonkernel operating system programs that are accessed by users

What is the /media Directory?

In newer distributions of UNIX/Linux, mount points for removable storage are in /media Relatively new recommendation of the Filesystem Hierarchy Standard (FHS) Modern Linux distributions include both /mnt and /media directories Users and programmers are often encouraged to use /media

The file system's organization is?

Is a hierarchical structure similar to an inverted tree; that is, it is a branching structure in which top-level files contain other files,which in turn contain other files.

What is a physical file system?

Is a section of the hard disk that has been formatted to hold files. UNIX/Linux consist of multiple file systems that form virtual storage space for multiple users

What is a wildcard?

Is a special character that can stand for any other character or, in some cases, a group of characters. * represents any group of characters in a file name ? takes the place of only a single character

~

Is shorthand for the home directory, which typically has the same name as the user's account name.

What is the /var Directory?

Located on the /var partition Holds subdirectories that often change in size These subdirectories contain files such as error logs and other system performance logs Common subdirectories are: /var/spool/mail for incoming mail /var/spool/lpd for temporarily holding print files

What is /tmp Directory?

Many programs need a temporary place to store data during processing cycles The traditional location for these files is /tmp

What is virtual memory mean?

Means you have what seem to be unlimited memory resources.Swap partitions accomplish this by providing swap space on a disk and treating it like an extension of memory (RAM).It is called swap space because the system can use it to swap information between disk and RAM.Setting up swap space makes your computer run faster and more efficiently.

What is the /mnt Directory?

Mount points for temporary mounts by the system administrator reside in /mnt A temporary mount is used to mount a removable storage medium Example: CD/DVD or USB/flash storage /mnt is often divided into subdirectories to clearly specify device types Example: /mnt/cdrom

What is a symbolic link?

Name, file name, or directory name that contains a pointer to a file/directory in the same directory or in another directory on your system

What does the /bin Directory contain?

Programs needed to start the system and perform other essential system tasks Holds many programs that all users need to work with UNIX/Linux

What are utilities?

Programs that perform operations such as copying files, listing directories, and communicating with other users

What is the /sbin Directory?

Reserved for the system administrator Stores: Programs that start the system Programs needed for file system repair Essential network programs

What is a partition?

Section of disk that holds a file system UNIX/Linux partitions identified with names Examples: hda1, sda1 First two letters tell Linux the device type Third letter indicates if disk is the primary or secondary disk Partitions on a disk are numbered starting with 1

How is Set group ID (SGID) bit: s (used in place of x)?

Similar to SUID, but applies to groups

What is a Directory?

Special kind of file that can contain other files and directories May have subdirectories Subdirectory is considered child of parent directory

What is virtual storage?

Storage that can be allocated using different disks or file systems (or both), but that is transparently accessible as storage to the operating system and users UNIX/Linux consist of multiple file systems that form virtual storage space for multiple users

In UNIX/Linux, you can refer to a path as either an absolute path or a relative path. A relative path

Takes a shorter journey. You can enter the relative path to begin at your current working directory and proceed from there.

What is a file system is?

The UNIX/Linux system's way of organizing files on storage devices, such as hard disks and CDs or DVDs.

In UNIX/Linux, a file is?

The basic component for data storage. UNIX/Linux consider everything with which they interact a file, even attached devices such as the monitor, keyboard, and printer.

A single dot character means?

The current working directory

What is journaling?

The file system keeps a log (journal) of its own activities. If the operating system crashes or is not properly shut down, such as during a power failure, the operating system reads the journal file when it is restarted.

What is extended file system (ext or ext fs)?

The native file system Installed by default Modeled after ufs First version contained some bugs Newer versions of Linux use ext2, ext3, or ext4 ext4 enables the use of extents

Dot dot means ?

The parent directory

What is the mkdir command used for?

To create a new directory

What is pwd used for?

To determine your current working directory

What is /var partition used for?

To hold files that are created temporarily, such as files used for printing documents (spool files) and files used to record monitoring and administration data, often called log files.

What are peripherals?

connect through electronic interfaces Examples of hard disk interfaces: IDE, SCSI, EIDE Computer storage devices such as hard disks. Computer peripherals connect to the computer through electronic interfaces. The two most popular hard disk interfaces are Integrated Drive Electronics (IDE) and Small Computer System Interface (SCSI). Enhanced IDE (EIDE),

What is the /home Directory?

is often on the /home partition and is used to offer disk space for users, such as on a system that has multiple user accounts. Ex.three home directories exist for three user accounts: /home/jean, /home/tricia, and /home/joseph.

What is rm-r used for?

rm -r is used to delete a directory that is not empty

What are three advanced permissions?

sticky bit, set user id (SUID) bit, and set group ID (SGID) bit.

What is a /boot partition used for?

to store OS kernel files