---
name: "copy_to_user"
section: "9"
platform: "linux"
package: "linux-manual-3.2"
version: "3.2.78-1"
release: "Debian 7 (Wheezy)"
platforms: ["linux"]
url: "https://new.carta.tech/copy_to_user"
---

# copy\_to\_user(9)

Copy a block of data into user space.

## NAME

copy\_to\_user - Copy a block of data into user space.

## SYNOPSIS

**unsigned long copy\_to\_user(void \_\_user \*** *to***, const void \*** *from***, unsigned long** *n***);**

## ARGUMENTS

*to*

Destination address, in user space.

*from*

Source address, in kernel space.

*n*

Number of bytes to copy.

## CONTEXT

User context only. This function may sleep.

## DESCRIPTION

Copy data from kernel space to user space.

Returns number of bytes that could not be copied. On success, this will be zero.

## COPYRIGHT