---
name: "ulimit"
section: "3"
platform: "linux"
package: "man-pages"
version: "6.19-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux", "freebsd", "macos"]
url: "https://new.carta.tech/ulimit/3"
---

# ulimit(3)

get and set user limits

## NAME

ulimit - get and set user limits

## LIBRARY

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

## SYNOPSIS

```
#include <ulimit.h>
```

**\[\[deprecated\]\] long ulimit(int** *cmd***, long** *newlimit***);**

## DESCRIPTION

Warning: this routine is obsolete. Use [**getrlimit**(2)](/getrlimit/2.md), [**setrlimit**(2)](/setrlimit/2.md), and [**sysconf**(3)](/sysconf/3.md) instead. For the shell command **ulimit**, see [**bash**(1)](/bash/1.md).

The **ulimit**() call will get or set some limit for the calling process. The *cmd* argument can have one of the following values.

- **UL\_GETFSIZE**

  Return the limit on the size of a file, in units of 512 bytes.

- **UL\_SETFSIZE**

  Set the limit on the size of a file.

- **3**

  (Not implemented for Linux.) Return the maximum possible address of the data segment.

- **4**

  (Implemented but no symbolic constant provided.) Return the maximum number of files that the calling process can open.

## RETURN VALUE

On success, **ulimit**() returns a nonnegative value. On error, -1 is returned, and *errno* is set to indicate the error.

## ERRORS

- **EPERM**

  An unprivileged process tried to increase a limit.

## ATTRIBUTES

For an explanation of the terms used in this section, see [**attributes**(7)](/attributes/7.md).

| | | |
| --- | --- | --- |
| **Interface** | **Attribute** | **Value** |
| **ulimit**() | Thread safety | MT-Safe |

## STANDARDS

POSIX.1-2008.

## HISTORY

SVr4, POSIX.1-2001. POSIX.1-2008 marks it as obsolete.

## SEE ALSO

[**bash**(1)](/bash/1.md), [**getrlimit**(2)](/getrlimit/2.md), [**setrlimit**(2)](/setrlimit/2.md), [**sysconf**(3)](/sysconf/3.md)