---
name: "fastboot"
section: "8"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["freebsd"]
url: "https://new.carta.tech/fastboot/8"
---

# fastboot(8)

stopping and restarting the system

## NAME

**reboot**, **halt**, **fastboot**, **fasthalt** – stopping and restarting the system

## SYNOPSIS

**halt** \[**-DflNnpq**\] \[**-e** *variable=value*\] \[**-k** *kernel*\] \[**-o** *options*\]

**reboot** \[**-cDdflNnpqr**\] \[**-e** *variable=value*\] \[**-k** *kernel*\] \[**-o** *options*\]

**fasthalt** \[**-DflNnpq**\] \[**-e** *variable=value*\] \[**-k** *kernel*\] \[**-o** *options*\]

**fastboot** \[**-dDflNnpq**\] \[**-e** *variable=value*\] \[**-k** *kernel*\] \[**-o** *options*\]

## DESCRIPTION

The **halt** and **reboot** utilities stop and restart the system, respectively.

Both utilities have two distinct modes of operation. In normal mode, they send a signal to the [init(8)](/init/8.md) process, which shuts down running services and stops or restarts the system. In fast mode, they flush the file system cache to disk, send all running processes a SIGTERM (and subsequently a SIGKILL) and stop or restart the system themselves. Services are killed, not shut down, which may result in data loss.

In either mode, the action is logged, including entering a shutdown record into the user accounting database.

The following options are available:

- **-c**

  The system will turn off the power and then turn it back on if it can. If the power down action fails, the system will halt or reboot normally, depending on whether **halt** or **reboot** was called. At the present time, only the [ipmi(4)](/ipmi/4.md) driver implements the power cycle functionality and only on hardware with a BMC that supports power cycling. Unlike power off, the amount of hardware that supports power cycling is small.

- **-D**

  Delete existing **nextboot** configuration and exit.

- **-d**

  The system is requested to create a crash dump. This option is supported only when rebooting, and it has no effect unless a dump device has previously been specified with [dumpon(8)](/dumpon/8.md).

- **-e** *variable=value*

  Sets *variable* to *value* in the loader's and kernel's environment. If *value* is not already enclosed in double quotes, they will be added before writing to the **nextboot** configuration. Care should be taken if *value* contains any characters that are special to the shell or loader's configuration parsing code.

- **-f**

  Forced mode. Normally, **halt** or **reboot** checks for the presence of the next kernel, and absence of the */var/run/noshutdown* file. Without this flag, the operation is rejected if one of these checks fails.

- **-k** *kname*

  Boot the specified kernel *kname* on the next system boot. This is a one-shot option, the *default* kernel will be booted on successive boots. No **reboot** or **halt** will be performed if */boot/kname/kernel* does not exist unless the **-f** flag is specified.

- **-l**

  The halt or reboot is *not* logged to the system log. This option is intended for applications such as [shutdown(8)](/shutdown/8.md), that call **reboot** or **halt** and log this themselves.

- **-N**

  The file system cache is not flushed during the initial process clean-up, however the kernel level [reboot(2)](/reboot/2.md) is still processed with a sync. This option can be useful for performing a “best-effort” reboot when devices might be unavailable. This can happen when devices have been disconnected, such as with [iscsi(4)](/iscsi/4.md).

- **-n**

  The file system cache is not flushed. This option should probably not be used.

- **-o** *options*

  This option allows the passing of kernel flags for the next boot.

- **-p**

  The system will turn off the power if it can. If the power down action fails, the system will halt or reboot normally, depending on whether **halt** or **reboot** was called.

- **-q**

  The system is halted or restarted quickly and ungracefully, and only the flushing of the file system cache is performed (if the **-n** option is not specified). This option should probably not be used.

- **-r**

  The system kills all processes, unmounts all filesystems, mounts the new root filesystem, and begins the usual startup sequence. After changing vfs.root.mountfrom with [kenv(1)](/kenv/1.md), **reboot** **-r** can be used to change the root filesystem while preserving kernel state. This requires the [tmpfs(4)](/tmpfs/4.md) kernel module to be loaded because [init(8)](/init/8.md) needs a place to store itself after the old root is unmounted, but before the new root is in place.

The **fasthalt** and **fastboot** utilities invoke **halt** and **reboot**, respectively, in fast mode.

The [shutdown(8)](/shutdown/8.md) utility can be used to not only stop or restart the system right away, but also schedule a stop or restart in the future, and will, unlike **halt** and **reboot**, give users advance warning of their impending doom.

## EXAMPLES

Replace current root filesystem with UFS mounted from */dev/ada0s1a*:

```
kenv vfs.root.mountfrom=ufs:/dev/ada0s1a
reboot -r
```

This mechanism can also be used with NFS, with a caveat that it only works with NFSv4, and requires a numeric IPv4 address:

```
kenv vfs.root.mountfrom=nfs:192.168.1.1:/share/name
reboot -r
```

## SEE ALSO

[kenv(1)](/kenv/1.md), [reboot(2)](/reboot/2.md), [getutxent(3)](/getutxent/3.md), [ipmi(4)](/ipmi/4.md), [boot(8)](/boot/8.md), [dumpon(8)](/dumpon/8.md), [nextboot(8)](/nextboot/8.md), [savecore(8)](/savecore/8.md), [shutdown(8)](/shutdown/8.md), [sync(8)](/sync/8.md)

## HISTORY

A **reboot** utility appeared in 4.0BSD.

Historically, the [shutdown(8)](/shutdown/8.md) utility was used when the system needed to be halted or restarted cleanly in the normal course of operations, and the **halt** and **reboot** utilities were blunt instruments used only in single-user mode or if exceptional circumstances made a normal shutdown impractical. As other operating systems did away with this distinction, and it became clear that many users were unaware of it and were using **reboot** in the belief that it performed a clean shutdown, it was rewritten to conform to that expectation.