How to Use the Command 'fastboot' (with examples)
The ‘fastboot’ command is a powerful tool that allows communication with Android devices when they are in bootloader mode, boasting capabilities that the Android Debug Bridge (ADB) doesn’t cover. Fastboot is integral to Android development and device customization, providing access to critical functions such as unlocking the bootloader, flashing custom images, and more. Below, we explore various use cases demonstrating the practical applications and syntax of ‘fastboot’ commands, designed to help users get the most out of their Android devices.
Use case 1: Unlock the Bootloader
Code:
fastboot oem unlock
Motivation:
Unlocking the bootloader is often the first step for users who wish to customize their Android device beyond the manufacturer’s default restrictions. By unlocking the bootloader, developers and advanced users can install custom firmware, root the device, or modify system components that are usually off-limits. The bootloader is like a security gate; this command provides the key to open that gate.
Explanation:
fastboot: This invokes the fastboot protocol communication.oem: This indicates that an original equipment manufacturer (OEM) specific command is being used.unlock: This specifies the action to unlock the device bootloader.
Example Output:
...
OKAY [ 0.010s]
Finished. Total time: 0.010s
Use case 2: Relock the Bootloader
Code:
fastboot oem lock
Motivation:
Relocking the bootloader is crucial for users who want to return their device to its factory state, often necessary for warranty claims or selling the device. It also serves as a security measure to prevent unauthorized modifications.
Explanation:
fastboot: Runs the fastboot tool to communicate with the connected device.oem: Indicates an OEM-specific command is in use.lock: This command relocks the bootloader, restoring it to a locked state, preventing further modifications.
Example Output:
...
OKAY [ 0.008s]
Finished. Total time: 0.008s
Use case 3: Reboot the Device from Fastboot Mode into Fastboot Mode Again
Code:
fastboot reboot bootloader
Motivation:
Rebooting into the bootloader is helpful for ensuring that any changes made to the system are reloaded without fully rebooting the operating system. This is particularly useful during development and testing phases, where frequent system changes need verification.
Explanation:
fastboot: Initiates the fastboot protocol.reboot: Tells the device to reboot.bootloader: Specifies that the device should reboot into the bootloader mode instead of the regular operating system.
Example Output:
rebooting into bootloader...
OKAY [ 0.012s]
Finished. Total time: 0.012s
Use case 4: Flash a Given Image
Code:
fastboot flash path/to/file.img
Motivation:
Flashing an image directly onto a device allows for system upgrades, custom firmware installation, or recovery operations. It is critical for troubleshooting when the device operating system becomes corrupt or unresponsive.
Explanation:
fastboot: Engages fastboot communication.flash: Directs the tool to write an image to a specified partition or section of the device’s memory.path/to/file.img: The path syntax implies user specification for the location of the image file to be flashed. ‘file.img’ is the placeholder for the actual image file name.
Example Output:
sending 'system' (1024 KB)...
OKAY [ 0.123s]
writing 'system'...
OKAY [ 0.345s]
Finished. Total time: 0.468s
Use case 5: Flash a Custom Recovery Image
Code:
fastboot flash recovery path/to/file.img
Motivation:
Flashing a custom recovery image enables advanced options for managing and maintaining an Android device outside the stock recovery system. Custom recoveries like TWRP (Team Win Recovery Project) offer increased functionality, including the ability to flash ZIP files, manage partitions, and perform full backups and restores.
Explanation:
fastboot: Initiates the protocol to communicate with the device.flash: Indicates that a file will be written to the device.recovery: Specifies that the image to be flashed should replace the recovery partition.path/to/file.img: A placeholder path, indicating where the actual recovery image is stored on the user’s computer.
Example Output:
sending 'recovery' (8192 KB)...
OKAY [ 0.456s]
writing 'recovery'...
OKAY [ 0.679s]
Finished. Total time: 1.135s
Use case 6: List Connected Devices
Code:
fastboot devices
Motivation:
Listing connected devices helps verify the connection between a computer and Android devices currently in fastboot mode. It is an essential diagnostic step when handling multiple devices or ensuring that the correct device is being targeted for commands.
Explanation:
fastboot: The command-line tool used for interfacing with Android devices in bootloader mode.devices: Used to list all connected devices that are currently being recognized by fastboot.
Example Output:
HT4BMJT01219 fastboot
Use case 7: Display All Information of a Device
Code:
fastboot getvar all
Motivation:
Retrieving all device variables provides a comprehensive snapshot of the device’s configuration and status. This information aids in troubleshooting and development, giving developers insights into the current state of the device’s hardware and software components.
Explanation:
fastboot: Runs the fastboot utility.getvar: Short for ‘get variable’, it queries the device for specific information.all: Requests all available variables and information about the device.
Example Output:
(bootloader) version: 0.5
(bootloader) version-bootloader: 1.01
(bootloader) version-baseband: 1.02
(bootloader) product: nexus_5
(bootloader) serialno: HT4BMJT01219
...
Conclusion
The ‘fastboot’ command line utility opens up numerous possibilities for customizing and managing Android devices beyond typical usage. From unlocking the bootloader to flashing custom ROMs, fastboot is an indispensable tool for developers and tech enthusiasts seeking complete control over their devices. Understanding these commands ensures that users can confidently undertake modifications and recoveries on their Android devices with efficiency and precision.
