Question

When working in a Linux operating system and you mount a nfs permission on a drive, what default permission are given?

Working with swap partition as we have done, identify what a swap partition is and what is it used for? If a system has 16G or RAM, what is normal practice for the swap partition?

What is debugfs? what does this command aid in when working on a filesystem?

Answer 1

A Network File System (NFS) allows remote hosts to mount file systems over a network and interact with those file systems as though they are mounted locally. This enables system administrators to consolidate resources onto centralized servers on the network

Determining Access to a File or Directory

1. Determine your user name and group name by logging on to the host computer and typing id at a UNIX host prompt.
2. List the owner and group information and the permissions for the file or directory using the command ls -l at a host prompt

If a Linux filesystem (not e.g. FAT32, NTFS) is mounted then the directory permissions for the root directory are taken from the filesystem. root must either change the owner ( chown ) or permissions ( chmod , setfacl ) of the root directory or has to create subdirectories which are writable by the users.

To change directory permissions in Linux, use the following:

1. chmod +rwx filename to add permissions.
2. chmod -rwx directoryname to remove permissions.
3. chmod +x filename to allow executable permissions.
4. chmod -x filename to take out write and executable permissions.

Use the following procedure to automatically mount an NFS share on Linux systems:

1. Set up a mount point for the remote NFS share: sudo mkdir /var/backups.
2. Open the /etc/fstab file with your text editor : sudo nano /etc/fstab. ...
3. Run the mount command in one of the following forms to mount the NFS share

Network File System (NFS) is a distributed file system protocol that allows you to share remote directories over a network. With NFS, you can mount remote directories on your system and work with the remote files as if they were local files.

On Linux and UNIX operating systems, you can use the mount command to mount a shared NFS directory on a particular mount point in the local directory tree.

Installing NFS Client Packages

To mount an NFS share on a Linux system first you’ll need to install the NFS client package. The package name differs between Linux distributions.

• Installing NFS client on Ubuntu and Debian:
• sudo apt update
• sudo apt install nfs-common
• Installing NFS client on CentOS and Fedora:
• sudo yum install nfs-utils

Manually Mounting an NFS File Systems

Mounting a remote NFS share is the same as mounting regular file systems.

To mount an NFS file system on a given mount point, use the mount command in the following form:

mount [OPTION...] NFS_SERVER:EXPORTED_DIRECTORY MOUNT_POINT

Use the steps below to manually mount a remote NFS share on your Linux system:

1. First, create a directory to serve as the mount point for the remote NFS share:
2. sudo mkdir /var/backups
3. Mount point is a directory on the local machine where the NFS share is to be mounted.
4. Mount the NFS share by running the following command as root or user with sudo privileges:
5. sudo mount -t nfs 10.10.0.10:/backups /var/backups
6. Where 10.10.0.10 is the IP address of the NFS server, /backup is the directory that the server is exporting and /var/backups is the local mount point.
   On success, no output is produced.
   If you want to specify additional mount options, use the -o option. Multiple options can be provided as a comma-separated list. To get a list of all mount options type man mount in your terminal.
7. To verify that the remote NFS volume is successfully mounted use either the mount or df -h command.

Once the share is mounted, the mount point becomes the root directory of the mounted file system.

When you are manually mounting the share, the NFS share mount does not persist after a reboot.

There are several reasons why you would need swap. ... If your system uses resource heavy applications like video editors, it would be a good idea to use some swap space as your RAM may be exhausted here. If you use hibernation, then you must add swap because the content of the RAM will be written to the swap partition.

There are several reasons why you would need swap.

• If your system has RAM less than 1 GB, you must use swap as most applications would exhaust the RAM soon.
• If your system uses resource heavy applications like video editors, it would be a good idea to use some swap space as your RAM may be exhausted here.
• If you use hibernation, then you must add swap because the content of the RAM will be written to the swap partition. This also means that the swap size should be at least the size of RAM.
• Avoid strange events like a program going nuts and eating RAM.

We can create a swap partition that is used by Linux to store idle processes when the physical RAM is low. The swap partition is disk space set aside on a hard drive. It is quicker to access RAM than files stored on a hard drive.

If you have a large amount of RAM — 16 GB or so — and you don't need hibernate but do need disk space, you could probably get away with a small 2 GB swap partition. Again, it really depends on how much memory your computer will actually use. But it's a good idea to have some swap space just in case.

The debugfs program is an interactive file system debugger. It can be used to examine and change the state of an ext2, ext3, or ext4 file system. device is a block device (e.g., /dev/sdXX) or a file containing the file system.

Here is a list of the most commonly used commands:

• show_super_stats or stats – produces superblock information, similar to what dumpe2fs displays.
• undelete INODE NAME – undeletes a file. INODE is the inode number of the deleted file and NAME the filename you want to give to it. You can get a list of deleted inodes by typing list_deleted_inodes.
• write INTERNAL_FILE EXTERNAL_FILE – extracts a file from the file system. INTERNAL_FILE is the name of a file in the file system you’re manipulating and EXTERNAL_FILE is a filename on your main Linux system. This command comes in handy when you want to extract a critical file without mounting the file system first.
• stat filename – displays the inode data on a file or directory.
• help – shows the commands available.
• quit – quits the program.