What is the command to create a file system in Linux?

The command to create a file system in Linux is mkfs.

This command has several variations, each designed for a specific file system type. Here are some of the most common ones:

mkfs.ext4: Creates an ext4 file system, the default file system for most modern Linux distributions.
mkfs.ext3: Creates an ext3 file system, a previous version of the ext4 file system.
mkfs.ext2: Creates an ext2 file system, an older version of the ext3 file system.
mkfs.xfs: Creates an XFS file system, known for its performance and reliability.
mkfs.btrfs: Creates a Btrfs file system, a modern file system with advanced features like snapshots and data integrity checks.

To use these commands, you need to specify the target device, for example, /dev/sdb1.

Creating an ext4 file system on /dev/sdb1:
```
  sudo mkfs.ext4 /dev/sdb1
```
Creating an XFS file system on /dev/sdb1:
```
  sudo mkfs.xfs /dev/sdb1
```

Remember to replace /dev/sdb1 with the actual device you want to format.

Before formatting a device, make sure you have a backup of any important data. Formatting a device will erase all data on it.

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