Chapters 4 - 5
What special character is used as wildcards?
*', "?", "[ ]", "~" and many more
Assignment: Module 5 Review Quiz A device file _______________________.
- has no data section. - displays a major and minor number in place of a file size.
Module 4 Review Quiz After typing the command umask 731, the permissions on all subsequently created files and directories will be effected. In this case, what will be the permissions on all new files?
---r--rw-
Module 4 Review Quiz The command chmod 317 file1 would produce which of the following lines in the ls command?
--wx--xrwx 1 user1 root 0 Apr 29 15:40 file1
Assignment: Module 5 Review Quiz Jim has just installed two new SAS SSDs in his system. He properly installs the hardware in his machine. Before he can use them for data storage and retrieval, what must he do?
-Create one or more partitions on each of the SSDs. -Mount any partitions created on the two SSDs such that they are accessible by the operating system. -Format any partitions created on the SSDs with a valid filesystem recognized by Linux
Lab 5-6: Check and Repair Filesystems: Linux Installation and configuration Using which parameter of the fsck command can you check the mounted file systems?
-M
Lab 5-6: Check and Repair Filesystems: Linux Installation and configuration Which parameter should you use with the fsck command to view the list of unmounted filesystems?
-M
Assignment: Module 5 Review Quiz Which of the following statements are true?
-Quotas can limit both user space and the number of files a user can own. -Hard limits can never be exceeded. -Soft limits allow a user to exceed them for a certain period of time.
Lab 5-3: Using Various Disk Management Tools Which parameter should you use to list the empty devices with the lsblk command?
-a
Lab 5-7: Managing Disk Quotas: Linux installation and configuration Which parameter of the quotacheck command checks for locally mounted filesystems that have quota enabled?
-a
Lab 5-6: Check and Repair Filesystems: Linux Installation and configuration Which two parameters should you use with fsck to auto repair errors if they are detected?
-a -y
Lab 5-3: Using Various Disk Management Tools Which parameter should you use to list the device size in bytes with the lsblk command?
-b
Lab 5-7: Managing Disk Quotas: Linux installation and configuration Which parameter of quotacheck command creates the quota files for each filesystem that has quota enabled?
-c
Lab 5-3: Using Various Disk Management Tools Which parameter of the lsblk command will list only the main devices, not the slave devices?
-d
Lab 5-8: Maintain the Integrity of Filesystems: Linux installation and configuration Which parameter should you use with the fsck command to force to check the integrity of a filesystem?
-f
Lab 5-7: Managing Disk Quotas: Linux installation and configuration Which parameter of the quotacheck command checks for the group quota?
-g
Assignment: Module 5 Test Callie wants to make sure that a filesystem is checked every 20 days. Which of the following options, when used with the tune2fs command, would set a full filesystem check to run every 14 days?
-i 14d
To copy a directory and the files contained in it to another directory, which of the following parameter should be used with the cp command?
-r
What parameter should be used with the rm command to remove a directory?
-r
Which parameter is used to create a symbolic link rather than a hard link with the ln command?
-s
Lab 5-7: Managing Disk Quotas: Linux installation and configuration Which parameter of the quotacheck command creates the quota files for a user quota?
-u
Assignment: Module 5 Review Quiz Given the following output from /etc/fstab, which filesystems will be automatically checked on boot by the fsck command?
/, /proc, and swap
Given the following output from /etc/fstab, which filesystems will be automatically checked on boot by the fsck command? /dev/sda1 / ext4 defaults 1 1 none /dev/pts devpts gid=5,mode= 620 1 0 none /proc proc defaults 0 1 none /dev/shm tmpfs defaults 1 0 /dev/sdc2 swap swap defaults 0 1 /dev/dvd /media/dvd iso 9660 noauto,ro 0 0 /dev/fd0 /media/floppy auto noauto 0 0 a. none, as fsck must be run manually for each filesystem b. /, /dev/pts and /dev/shm c. /, /proc and swap d. all of them, as fsck is run automatically at boot for all filesystems
/,/dev/pts and dev/shm
(Lab 4-1) Where is the pwd command located on this system?
/bin
Assignment: Module 5 Test Which of the following would be the device file for the third partition on the second SATA drive on a Linux system?
/dev/sdb3
Assignment: Module 5 Review Quiz You plug a USB flash memory drive into a system that has two SATA hard disks. How will the partition on this USB flash memory drive be identified by Linux?
/dev/sdc1
You plug a USB flash memory drive into a system that has two SATA hard disks. How will the partition on this USB flash memory drive be identified by Linux? a. /dev/sdb1 b. /dev/sda1 c. /dev/sda2 d. /dev/sdc1
/dev/sdc1
Assignment: Module 5 Test Jackson wants to automatically mount a secondary internal hard drive when his Linux workstation boots up. In which of the following files should he configure an entry for the partition on the drive that he wants to mount?
/etc/fstab
Lab 5-4: Control Mounting and Unmounting of Filesystems The _______ file lists the partitions that will be detected at the boot time. It also defines which filesystem is mounted as the root partition (/).
/etc/fstab
Lab 5-7: Managing Disk Quotas: Linux installation and configuration To configure the disk quota, you first add the filesystems that require the quotas implemented to the _________ file.
/etc/fstab
Module 4 Test Lynn runs the locate command and the results include many files from a directory that she doesn't want to include in her search. Which of the following files could Lynn modify so that the locate command no longer includes those results?
/etc/updatedb.conf
Lab 5-4: Control Mounting and Unmounting of Filesystems To mount a CD-ROM, in which directory should you create a directory?
/mount
Lab 5-5: View the Hard Drive Details You can use view the ______ file to view the hard drive details.
/proc/partitions
Module 4 Test Which of the following umask settings will result in new files receiving the default permissions -rw-------?
0177
Lab 5-2: Create Partitions and Filesystems What is the number of MBR partitions contained in a hard drive?
1
Chapter 4 Test Prep What commands will change group ownership of a file to finance? (Choose all that apply.)
1. chgrp finance myfile 2. chgrp -v finance myfile 3. chown :finance myfile
What is the size of /dev/sda in GB?
21.5
(Lab 4-1) The inode number of the links file is 267865. What is the inode number of the links2 file?
267865
Assignment: Module 5 Test If the physical extent of a volume group is set to 32MB, what is the maximum logical volume size?
2TB
Lab 5-2: Create Partitions and Filesystems What is the maximum number of primary and extended partitions can you define on a hard drive?
4
What sector size in bytes is used on /dev/sda?
512
(Lab 4-1) What is the numeric representation of the mode of a newly created directory? in the space provided, enter only the numeric value.
777
Lab 5-2: Create Partitions and Filesystems When using the gdisk command, what is the default GUID used?
8300
Filesystem hierarchy Standard (FHS)
A standard outlining the location of set files and directories on a Linux or UNIX system
What is recursive?
A term referring to itself and its own contents; a recursive search includes all subdirectories in a directory and their contents.
Module 4 Review Quiz You noticed a file in your home directory that has a + symbol appended to the mode. What does this indicate?
Additional entries exist within the ACL of the file that can be viewed using the getfacl command.
What directories are contained within the root directory?
Boot, etc, home
(Lab 4-1) We used 765 in this lab to set the mode of a file named project2. If we had used the value 675 who would be affected?
Both user and group
Module 4 Review Quiz What was created to define a standard directory structure and common file location for Linux?
FHS
After a partition on a hard disk drive is formatted with a filesystem, all partitions on that hard disk drive must use the same filesystem. True or false.
False
Assignment: Module 5 Review Quiz After a partition on a hard disk is formatted with a filesystem, all partitions on that hard disk drive must use the same filesystem. True or False?
False
Assignment: Module 5 Review Quiz Character devices typically transfer data more quickly than block devices. True or False?
False
Character devices typically transfer data more quickly than block devices. True or false
False
Module 4 Review Quiz A symbolic link is also known as a soft link and is depicted by an @ symbol appearing at the beginning of the filename when viewed using the ls -l command. True or False?
False
Module 4 Review Quiz Only the root user can modify a file that has the immutable attribute set. True or False?
False
Module 4 Review Quiz There is no real difference between the "S" and "s" special permissions when displayed using the ls -l command. One just means it is on a file, and the other that it is on a directory. True or False?
False
Which of the following does iso9660 identity?
Filesystem
Which type of link is another directory entry for the source file and carries those same properties, such as file permissions, of the source file?
Hard link
Which type of link can only exist on the local system?
Hardlink
A device file ______. a. has no size b. has a fixed size of 300 kilobytes c. has no inode section d. displays a major and minor number in place of a file size
Has no data section d.displays a major and minor number in place of a file size
Module 4 Review Quiz What does the mv command do?
It moves a directory. It moves a file.
Module 4 Review Quiz What must a user do to run cp or mv interactively and be asked whether to overwrite an existing file?
Just type cp or mv as they run in interactive mode by default.
A user runs the fsck command with the -a option on a filesystem that is showing signs of corruption. How would that user locate any files the system was unable to repair? A user runs the fsck command with the -a option on a filesystem that is showing signs of corruption. How would that user locate any files the system was unable to repair? a. The system prompts the user for a target location when it comes across a file it cannot repair. b. View the contents of the directory /lost+found. c. Mount the filesystem and check the lost+found directory underneath the mount point. d. Look in the root of the filesystem.
Mount the filesystem and check the lost+found directory underneath the mount point
Assignment: Module 5 Review Quiz A user runs the fsck command with the -f option on an ext4 filesystem that is showing signs of corruption. How would that user locate any files the system was unable to repair?
Mount the filesystem and check the lost+found directory underneath the mount point.
Which of the following statements are true? a. Hard limits allow a user to exceed them for a certain period of time. b. Quotas can limit both user space and the number of files a user can own. c. Quotas can only limit user space. d. Quotas can only limit the number of files a user can own.
Quotas can limit both user space and the number of files a user can own.
Lab 5-3: Using Various Disk Management Tools Which of the following tasks can be performed using disk management tools in Linux?
Remove partitions Create partitions Monitor free and used space Specifying the type of filesystem on a partition
Module 4 Review Quiz The root user utilizes the chgrp command to give ownership of a file to another user. What must the root user do to regain ownership of the file?
Run chgrp again listing the root user as the new owner.
Assignment: Module 5 Test Aria has modified the hard disk that hosts the operating system by using the fdisk command. The fdisk command indicates that the new partition information must be manually reloaded. Which of the following should she do next? (Choose two. Either answer is independently correct.)
Run the partprobe command Reboot the system
Lab 5-1: Working with fdisk Options and Mount - Unmount Filesystems When using the fdisk -l command, what type of device contains the boot partition?
SATA/SCSI
What does the du /var command do? a. shows the size of all directories within the /var directory b. dumps the /var directory c. shows the users connected to the /var directory d. displays the amount of free space in the /var directory
Shows the size of all directories within the /var directory (FROM TEST displayes amount of free space in /var directory)
What is a separate partition that moves items from computer memory to its hard drive?
Swap
Which type of link is a pointer to the source file?
Symbolic link
Chapter 4 Test Prep If a hard link is created for a file and then the original file is deleted, what is the status of the hard link as a result?
The hard link is still accessible with all of the original contents of the original file.
What is interactive mode?
The mode that file management commands use when a file can be overwritten; the system interacts with a user asking the user to confirm the action.
What is Pruning?
The process of excluding files, directories, or filesystems from being processed by a command
Lab 5-3: Using Various Disk Management Tools Which of the following information is displayed using the lsblk command?
The total size of the partition The mount points if any available The total size of the block
Module 4 Test What would be the result of running the command chown :root file1.txt
This would set the group ownership of file1 to root.
Assignment: Module 5 Review Quiz The lvextend command can be used to add unused space within a volume group to an existing logical volume. True or False?
True
Module 4 Review Quiz Hard links need to reside on the same filesystem as the target, whereas symbolic links need not be on the same filesystem as the target. True or False?
True
The lvextend command can be used to add additional unused space within a volume group to an existing logical volume. True or false
True
A user mounts a device to a mount point directory and realizes afterward that there are files previously found within the mount point directory that are needed. What would this user do? a. Nothing; the files are lost and cannot ever be accessed. b. Unmount the device from the directory. c. Run the fsck command to recover the file. d. Nothing; the files could not have been there as you can only mount to empty directories. e. Look in the lost+found directory for the file.
Unmount the device from the directory
You find that a device file in the /dev directory has become corrupted. You know that this device is /dev/tty3 and that it is a character device file. What should you do?
Use the /dev/MAKEDEV command to re-create the file
Jim has just purchased two new SCSI hard disk drives and a controller card for them. He properly installs the hardware in his machine. Before he can use them for data storage and retrieval, what must he do? a. Mount a filesystem to each of the hard disk drives. b. Mount any partitions created on the two hard drives such that they are accessible by the operating system. c. Use the vi editor to edit /etc/mtab and create an entry for the controller card and the hard disk drives. d. Mount the two hard drives so they are accessible by the operating system. e. Remove the format of any partitions created with a valid filesystem recognized by Linux. f. Use the btrfs command to create one or more partitions on each of the hard disk drives.
Use the fdisk command to create one or more partitions on each of the hard disk drives mount any partitions created on the two hard drives so that they are accessible by the operating system Format any partitions created with a valid filesystem recognized by Linux (FROM TEST Mount any partitions created on the two hard drives such that they are accessible by the operating system)
Module 4 Review Quiz After typing the ls -F command, you see the following line in the output: -rw-r-xr-- 1 user1 root 0 Apr 29 15:40 file1
User1 has read and write, members of the root group have read and execute, and all others have read permissions to the file.
Which of the following statements regarding LVM structure is correct? a. VGs are comprised of one or more PVs b. PVs are collections of VGs c. LVs are created from the free space available within PVs d. PVs use the space within LVs to create VGs
VGs are composed of one or more PVs
Assignment: Module 5 Review Quiz Which of the following statements regarding LVM structure is correct?
VGs are comprised of one or more PVs.
Lab 5-4: Control Mounting and Unmounting of Filesystems Which command should you use to find the UID of a filesystem?
blkid
Lab 5-1: Design Hard Disk Layout Which of the following sub-directories are part of the root directory?
boot usr home var tmp
You want to see the filesystems that are presently in use on the system. What command could you use? a. cat /etc/fstab b. ls -l /etc/fstab c. cat /etc/mtab d. ls -l /etc/fstab
cat /etc/mtab
Assignment: Module 5 Review Quiz You want to see the filesystems that are in use on the system. What command could you use?
cat /etc/mtab df -T
Module 4 Review Quiz When applied to a directory, the SGID special permission____________________.
causes all new files created in the directory to have the same group membership as the directory and not the entity that created them
Module 4 Review Quiz A file has the following permissions r----x-w-. The command chmod 143 would have the same effect as the command _________. (Choose all that apply.)
chmod u=x,g=r,o=wx file1
Chapter 4 Test Prep Francis has just taken over a new project. You need to change the owner of the project directory as well as all of the files and subdirectories in that directory to be owned by Francis. What command could you use?
chown -R francis projecto
Chapter 4 Test Prep Ferris needs to change the ownership of a directory named projectx to a new user and all of the directories within it. What command could he use?
chown -R projectx billyj
Module 4 Review Quiz Which of the following commands will change the user ownership and group ownership of file1 to user1 and root, respectively?
chown user1:root file1
Celeste needs to rename the project5 directory to something a bit more descriptive. Utilizing the command line, which of the following would accomplish this task? (Choose all that apply.)
cp project5 newbuildingproject NEED TO Verify
Assignment: Module 5 Review Quiz Which command is used to display the amount of free space that exists on a filesystem?
df
Lab 5-5: View the Hard Drive Details The _______ command displays the information about the mounted filesystems.
df
Lab 5-5: View the Hard Drive Details The _______ utility is meant to list the disk space usage on filesystems.
df
Which command is used to display the amount of free space that exists on a filesystem? a. du b. df c. quota d. fsck
df
Lab 5-8: Maintain the Integrity of Filesystems: Linux installation and configuration Which command should you use to determine the partition of the current working directory?
df .
What does the command dumpe2fs -h do? a. is not a valid command b. displays the number of inodes used and available in an ext2 filesystem c. backs up an ext2 filesystem d. dumps an ext2 filesystem
displays the number of inodes used and available in an ext2 filesystem
Assignment: Module 5 Review Quiz What does the command dumpe2fs -h do?
displays the number of used and available inodes for an ext2/ext3/ext4 filesystem
Assignment: Module 5 Review Quiz What does the du -s /var command do?
displays the total size of the /var directory
Lab 5-8: Maintain the Integrity of Filesystems: Linux installation and configuration Which command is used to determine the disk usage?
du
Lab 5-1: Design Hard Disk Layout Which command will allow you to find out the total space taken by each of the directories in a Linux system?
du -h --max-depth=1
Assignment: Module 5 Review Quiz Which command is used to format a partition on a hard disk drive with the ext4 filesystem?
e2mkfs -t ext4 device
Lab 5-6: Check and Repair Filesystems: Linux Installation and configuration After issuing the fsck -M /dev/sda1 command, which command should generate the output as 0 or 1?
echo $?
What are two directories that contain files that are static and cannot be changed by a user?
etc and boot
Module 4 Review Quiz What are the three standard Linux permissions?
execute, read, write
Lab 5-2: Create Partitions and Filesystems Which command allows you to display the existing partitions on a disk?
fdisk -l
Lab 5-8: Maintain the Integrity of Filesystems: Linux installation and configuration Which type of information is indicated by an inode?
file size, file type, access permission
Which command works only when you are in the root directory
find
Lab 5-6: Check and Repair Filesystems: Linux Installation and configuration Which utility can repair a damaged filesystem?
fsck
Lab 5-8: Maintain the Integrity of Filesystems: Linux installation and configuration Which command is used to verify the integrity of a filesystem?
fsck
Assignment: Module 5 Review Quiz Which of the following commands can only be used to create partitions on a GPT hard disk?
gdisk
(Lab 4-1) When searching with the which command, most of the commands were found in the same directory. Which of the choices was in a different directory than the others? (ls, pwd, cp, mv, halt)
halt
The iso9660 filesystem is used on CD-ROMs. What filesystem is used if you convert a CD-Rom to a disk image ISO file?
isso9660
Which command is used to create links?
ln
Chapter 4 Test Prep Peter has configured a Linux server so that the operating system and swap are on /dev/sda and the user home directories are on /dev/sdb. He wants to create a link in his home directory to the syslog file in /var/log. What command could create that link?
ln -s /var/log/syslog /home/peter/syslog
Module 4 Test Which of the following commands will create a symbolic link named foo.txt to an original file named bar.txt
ln -s bar.txt foo.txt
Module 4 Test This would set the group ownership of file1 to root.
lrwxrwxrwx
Lab 5-5: View the Hard Drive Details The __________ utility is meant to list the SCSI devices on a system.
lsscsi
What is the command used to create directories?
mkdir
Module 4 Test Mindy wants to create a new subdirectory at ~/2019projects/projectx/projectplans to start storing the initial project plans for projectx. However, this is the first project she has worked on in 2019 and the 2019projects directory does not exist yet. Which of the following commands will create the higher level directories if they do not already exist?
mkdir -p ~/2019projects/project/projectplans
To create a subdirectory within a directory, which of the following command should be used?
mkdir myfolder/mydocs
Which command is used to format a partition on a hard disk drive with the ext4 filesystem? a. format_ext4 device b. e2mkfs -t ext4 device c. ext4mkfs device d. makeext4FS device
mke2fs -t ext4 device FROM TEST e2mkfs -t ext4 device
Assignment: Module 5 Test Which of the following commands cannot be used to create an exFAT filesystem on a USB thumb drive that is recognized as /dev/sdb?
mkfs exfat /dev/sdb1
Lab 5-1: Design Hard Disk Layout Which of the following command lists all the partitions and their mount points on a hard disk?
mount
Assignment: Module 5 Review Quiz Which command mounts all existing filesystems in /etc/fstab?
mount -a
Which command mounts all existing filesystems in /etc/fstab? a. mount /etc/fstab b. mount -f c. mount -a d. mount /etc/mtab
mount -a
Lab 5-4: Control Mounting and Unmounting of Filesystems To view the current partitions mounted, which command should you use?
mount -v
Module 4 Review Quiz Which command do you use to rename files and directories?
mv
What is a command used to move/rename files and drectories?
mv
Chapter 4 Test Prep Celeste needs to rename the project5 directory to something a bit more descriptive. Utilizing the command line, what would accomplish this task?
mv project5 newbuildingproject
Which of the following commands can be used to create partitions on either a MBR or GPT hard disk? a. parted b. gdisk c. fdisk d. cdskck
parted
Assignment: Module 5 Test Clint has run the command parted /dev/sdb and wants to display a list of the existing partitions that exist on that drive. Which of the following commands can he use to display the existing partitions?
A term referring to itself and its own contents? A recursive search includes all subdirectories in a directory and their contents.
recursive
Which of the following command is used to delete a file?
rm
Module 4 Test Which of the following commands will delete a directory and all of the files contained within it? (Choose all that apply.)
rm -rf olddir
Chapter 4 Test Prep Jordan wants to remove an empty directory that is no longer being used. What commands could he use to accomplish this task?
rmdir olddir rm -r olddir
Module 4 Review Quiz The default permissions given by the system prior to analyzing the umask are ___________for directories and __________ for files.
rwxrwxrwx and rw-rw-rw-
Module 4 Review Quiz The which command _________________.
searches for a file only in directories that are in the PATH variable
Lab 5-5: View the Hard Drive Details The _________ utility is meant to print the drive information.
smartctl
What is the portion of a command that refers to the file or directory from which information is taken?
source file/directory
The mv command requires two arguments at minimum, what are they?
source file/directory (The portion of a command that refers to the file or directory from which info is taken) target file/directory (The portion of a command that refers to the file or directory to which information is directed) i.e. mv /etc/sample1 /root
Module 4 Review Quiz What does the /var directory contain?
spools and log files
Lab 5-1: Design Hard Disk Layout Which type of partition moves items from the computer memory to its hard drive?
swap
A stanard outlining the location of set files and directories on a Linux or UNIX system
target file/directory
Module 4 Review Quiz When you change the data in a file that is hard-linked to three others, __________.
the data in the file you modified as well as the data in all hard-linked files are modified because they share the same data and all have the same inode and file size
The first floppy drive on the system is not responding. You enter the file /dev/fd0 command and receive the following output. What is the problem? [root@server1 root]# file /dev/fd0 /dev/fd0: ASCII text [root@server1 root]# a. The device file has become corrupt. b. The floppy drive is seen as a character device. c. There is no floppy disk in the drive. d. The floppy drive cable has come loose.
the device file has become corrupt
Lab 5-4: Control Mounting and Unmounting of Filesystems When you boot a Linux system, the _____ filesystem is mounted as part of the initialization process.
the root (/) filesystem
Module 4 Test Which of the following commands can be used to update the last modified timestamp on a file, or if the file specified does not exist will create the file?
touch file.txt
Chapter 4 Test Prep Angie wants to update the access and modification times of an existing file named mydoc.txt. What command could she use to accomplish this task?
touch mydoc.txt
Module 4 Review Quiz Given the following output from the ls command, how many files are linked with file1? 1. drwxr-xr-x 3 root root 4096 Apr 8 07:12 Desktop 2. -rw-r--r-- 3 root root 282 Apr 29 22:06 file1 3. -rw-r--r-- 1 root root 282 Apr 29 22:06 file2 4. -rw-r--r-- 4 root root 282 Apr 29 22:06 file3 5. -rw-r--r-- 2 root root 282 Apr 29 22:06 file4 6. -rw-r--r-- 1 root root 282 Apr 29 22:06 file5 7. -rw-r--r-- 1 user1 sys 282 Apr 29 22:06 file6
two
Chapter 4 Test Prep When a new file is created, Linux needs to determine what permissions are initially set for that file. What command can modify the default permissions that are set on files created in a given directory?
umask
When a new file is created, Linux needs to determine what permissions are initially set for that file. Which of the following commands can modify the default permissions that are set on files created in a given directory?
umask need to verify
Assignment: Module 5 Test Elijah is done working with an external USB hard drive and wants to properly disconnect it. Which of the following commands should he use before unplugging the USB cable?
umount
What must you do to successfully run the fsck command on a filesystem? a. Choose yes when warned that running fsck on a mounted filesystem can cause damage. b. Unmount the filesystem. c. Run the fsck command with the -u option to automatically unmount the filesystem first. d. Ensure that the filesystem is mounted.
umount the filesystem
Lab 5-2: Create Partitions and Filesystems How many partitions does GPT allow you to create on a disk?
unlimited
Assignment: Module 5 Review Quiz A user mounts a device to a mount point directory and realizes afterward she needs files previously found within the mount point directory. What should this user do?
unmount the device from the directory.
Assignment: Module 5 Review Quiz What must you do to successfully run the fsck command on a filesystem?
unmount the filesystem.
Which of the following directories are unshareable?
var/log and /proc
Assignment: Module 5 Review Quiz Which command can be used to repair an XFS filesystem?
xfs_repair /dev/sdb1