---
name: "nice"
section: "2"
platform: "linux"
package: "man-pages"
version: "6.19-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/nice/2"
---

# nice(2)

change process priority

## NAME

nice - change process priority

## LIBRARY

Standard C library (*libc*, *-lc*)

## SYNOPSIS

```
#include <unistd.h>
```

**int nice(int** *inc***);**

Feature Test Macro Requirements for glibc (see [**feature\_test\_macros**(7)](/feature_test_macros/7.md)):

**nice**():

```
    _XOPEN_SOURCE
        || /* Since glibc 2.19: */ _DEFAULT_SOURCE
        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
```

## DESCRIPTION

**nice**() adds *inc* to the nice value for the calling thread. (A higher nice value means a lower priority.)

The range of the nice value is +19 (low priority) to -20 (high priority). Attempts to set a nice value outside the range are clamped to the range.

Traditionally, only a privileged process could lower the nice value (i.e., set a higher priority). However, since Linux 2.6.12, an unprivileged process can decrease the nice value of a target process that has a suitable **RLIMIT\_NICE** soft limit; see [**getrlimit**(2)](/getrlimit/2.md) for details.

## RETURN VALUE

On success, the new nice value is returned (but see VERSIONS below). On error, -1 is returned, and *errno* is set to indicate the error.

A successful call can legitimately return -1. To detect an error, set *errno* to 0 before the call, and check whether it is nonzero after **nice**() returns -1.

## ERRORS

- **EPERM**

  The calling process attempted to increase its priority by supplying a negative *inc* but has insufficient privileges. Under Linux, the **CAP\_SYS\_NICE** capability is required. (But see the discussion of the **RLIMIT\_NICE** resource limit in [**setrlimit**(2)](/setrlimit/2.md).)

## VERSIONS

### C library/kernel differences

POSIX.1 specifies that **nice**() should return the new nice value. However, the raw Linux system call returns 0 on success. Likewise, the **nice**() wrapper function provided in glibc 2.2.3 and earlier returns 0 on success.

Since glibc 2.2.4, the **nice**() wrapper function provided by glibc provides conformance to POSIX.1 by calling [**getpriority**(2)](/getpriority/2.md) to obtain the new nice value, which is then returned to the caller.

## STANDARDS

POSIX.1-2024.

## HISTORY

POSIX.1-2001, SVr4, 4.3BSD.

## NOTES

For further details on the nice value, see [**sched**(7)](/sched/7.md).

*Note*: the addition of the "autogroup" feature in Linux 2.6.38 means that the nice value no longer has its traditional effect in many circumstances. For details, see [**sched**(7)](/sched/7.md).

## SEE ALSO

[**nice**(1)](/nice/1.md), [**renice**(1)](/renice/1.md), [**fork**(2)](/fork/2.md), [**getpriority**(2)](/getpriority/2.md), [**getrlimit**(2)](/getrlimit/2.md), [**setpriority**(2)](/setpriority/2.md), [**capabilities**(7)](/capabilities/7.md), [**sched**(7)](/sched/7.md)