---
name: "ulimit"
section: "3"
platform: "macos"
package: "Libc"
version: "1752.120.2"
release: "macOS 26.5"
platforms: ["linux", "freebsd", "macos"]
url: "https://new.carta.tech/ulimit/3"
---

# ulimit(3)

get and set process limits

## NAME

**ulimit** – get and set process limits

## LIBRARY

Standard C Library (libc, -lc)

## SYNOPSIS

**#include \<ulimit.h\>**

*long*\

**ulimit**(*int cmd*, *...*);

## DESCRIPTION

The **ulimit**() function will get and set process limits. Currently, this is limited to the maximum file size. The *cmd* argument is one of the following:

- UL\_GETFSIZE

  will return the maximum file size of the current process, in units of 512-byte blocks.

- UL\_SETFSIZE

  will attempt to set the maximum file size of the current process and its children, using the second argument (expressed as a long).

## RETURN VALUES

Upon successful completion, **ulimit**() returns the value requested; otherwise, the value -1 is returned and the global variable *errno* is set to indicate the error.

## ERRORS

The **ulimit**() function will fail if:

- \[EINVAL\]

  The command specified was invalid.

- \[EPERM\]

  The limit specified to **ulimit**() would have raised the maximum limit value, and the caller is not the super-user.

## SEE ALSO

[getrlimit(2)](/getrlimit/2.md)

## STANDARDS

The **ulimit**() function conforms to IEEE Std 1003.1-2001 (“POSIX.1”).

## HISTORY

The **ulimit**() function first appeared in FreeBSD 5.0.

## BUGS

The **ulimit**() function provides limited precision for setting and retrieving process limits. If there is a need for greater precision than the type *long* provides, the [getrlimit(2)](/getrlimit/2.md) and [setrlimit(2)](/setrlimit/2.md) functions should be considered.