findmnt: Check Mounted File System Information

Overview

findmnt queries detailed information about mounted file systems on the current system based on data from sources like `/etc/fstab`, `/etc/mtab`, and `/proc/self/mountinfo`. It particularly excels at visualizing mount relationships in a tree format for easy understanding.

Key Features

Visualizes mounted file systems in a tree format
Supports various filtering options (type, source, target, etc.)
Provides JSON and RAW output formats
Offers functionality to query fstab file information

Key Options

findmnt allows you to control the output format and content through various options.

Output Format

Filtering

Information Source

Generated command:

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Description:

`findmnt` Executes the command.

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Usage Examples

Various usage examples of the findmnt command.

Display Basic Mount Information

findmnt

Shows all mounted file systems on the current system in a tree format.

Output in List Format

findmnt -l

Outputs mount information in a regular list format instead of a tree.

View Only Specific File System Types

findmnt -t ext4

For example, outputs only file systems of type 'ext4'.

View Information for a Specific Mount Point

findmnt -T /boot

For example, displays detailed information for the '/boot' mount point.

Output All Columns in JSON Format

findmnt --json -D

Outputs all mount information in JSON format, which is easy to parse by scripts or other programs.

Check fstab File Contents

findmnt --fstab

Outputs the contents defined in the `/etc/fstab` file, rather than the currently mounted file systems.

Tips & Notes

findmnt is a very useful tool for system administration and troubleshooting. Use the following tips to use it more efficiently.

Utilizing JSON Output

The `findmnt --json` option is highly beneficial for parsing mount information in scripts. When used with tools like `jq`, you can extract specific fields or perform complex queries.

Useful for script automation
Use in conjunction with JSON parsers like jq
Facilitates extraction and analysis of specific information

Comparing fstab and Actual Mounts

By using the `--fstab` option, you can compare the contents defined in `/etc/fstab` with the actual mounted state to identify system configuration errors.

Diagnosing system boot issues
Identifying unexpected mount errors
Verifying fstab configurations

Use in Troubleshooting

When file system related issues occur, findmnt helps quickly identify which device is mounted where, and with what options.