---
name: "trim"
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/trim"
---

# trim(8)

erase device blocks that have no needed contents

## NAME

**trim** – erase device blocks that have no needed contents

## SYNOPSIS

**trim** \[**-Nfqv**\] \[ **-\[lo\]** *offset* \[**K**\|**k**\|**M**\|**m**\|**G**\|**g**\|**T**\|**t**\|**P**\|**p**\|**E**\|**e**\]\] \[**-r** *rfile*\] *device* *...*

## DESCRIPTION

The **trim** utility erases specified region of the device. It is mostly relevant for a storage that implements trim (like flash based, or thinly provisioned storage). **All** **erased** **data** **is** **lost.**

The **trim** utility should not be used upon mounted file system or active devices being a part of imported ZFS pool or other software RAID, and the kernel does not permit such usage generally. If used upon not mounted file system or inactive device, the **trim** utility erases blocks non-selectively, whether a block is occupied or not. Refer to the [fsck\_ffs(8)](/fsck_ffs/8.md) command having a flag **-E** to trim free blocks inside populated UFS, and to the [zpool-trim(8)](/zpool-trim/8.md) command to trim existing ZFS pool.

The following options are available:

- **-N**

  Do not actually erase anything but show what it would do (dry run). Implies **-v**. This is the default. Overrides **-f**.

- **-f**

  Perform the operation. Overrides **-N**.

- **-l**

  *offset* \[**K**\|**k**\|**M**\|**m**\|**G**\|**g**\|**T**\|**t**\|**P**\|**p**\|**E**\|**e**\]

- **-o**

  *offset* \[**K**\|**k**\|**M**\|**m**\|**G**\|**g**\|**T**\|**t**\|**P**\|**p**\|**E**\|**e**\] Specify the length **-l** of the region to trim or its offset **-o** from the beginning of the device. **The** **whole** **device** **is** **erased** **by** **default** unless one or both of these options are presented.

  The argument may be suffixed with one of **K**, **M**, **G**, **T**, **P** or **E** (either upper or lower case) to indicate a multiple of Kilobytes, Megabytes, Gigabytes, Terabytes, Petabytes or Exabytes, respectively.

- **-q**

  Do not output anything except of possible error messages (quiet mode). Overrides **-v**.

- **-r** *rfile*

  Uses the length of given *rfile* as length of the region to erase. **The** **whole** **device** **is** **erased** **by** **default.**

- **-v**

  Show offset and length of actual region being erased, in bytes.

Later options override previous ones.

Note that actual success of the operation depends of underlying device driver such as [ada(4)](/ada/4.md), [da(4)](/da/4.md) and others. Refer to corresponding manual pages for detail on possible caveats in low level support for ATA TRIM or SCSI UNMAP commands.

## EXIT STATUS

The **trim** utility exits 0 on success, and \>0 if an error occurs. If the final erase operation fails for an argument, the **trim** utility returns exit code 1. It can also return one of the exit codes defined in [sysexits(3)](/sysexits/3.md), as follows:

- EX\_USAGE

  The specified offset or length of the region is incorrect.

- EX\_OSERR

  There is no enough memory to proceed.

- EX\_NOINPUT

  The specified *rfile* cannot be opened (perhaps, it does not exist).

- EX\_IOERR

  The specified *rfile* cannot be examined for its size due to some system input/output error.

- EX\_DATAERR

  The specified *rfile* is not regular file, directory nor special device, so its size cannot be examined.

- EX\_UNAVAILABLE

  The specified *rfile* is special device file not supporting DIOCGMEDIASIZE [ioctl(2)](/ioctl/2.md) (probably not a disk), so its size cannot be examined.

## SEE ALSO

[ioctl(2)](/ioctl/2.md), [sysexits(3)](/sysexits/3.md), [ada(4)](/ada/4.md), [da(4)](/da/4.md), [nda(4)](/nda/4.md), [fsck\_ffs(8)](/fsck_ffs/8.md), [zpool-trim(8)](/zpool-trim/8.md)

## HISTORY

The **trim** utility first appeared in FreeBSD 12.1.

## AUTHORS

The **trim** utility was written by Eugene Grosbein ⟨*eugen@FreeBSD.org*⟩.