---
name: "siginterrupt"
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/siginterrupt"
---

# siginterrupt(3)

allow signals to interrupt system calls

## NAME

siginterrupt - allow signals to interrupt system calls

## LIBRARY

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

## SYNOPSIS

```
#include <signal.h>
```

**\[\[deprecated\]\] int siginterrupt(int** *sig***, int** *flag***);**

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

**siginterrupt**():

```
    _XOPEN_SOURCE >= 500
        || /* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200809L
        || /* glibc <= 2.19: */ _BSD_SOURCE
```

## DESCRIPTION

The **siginterrupt**() function changes the restart behavior when a system call is interrupted by the signal *sig*. If the *flag* argument is false (0), then system calls will be restarted if interrupted by the specified signal *sig*. This is the default behavior in Linux.

If the *flag* argument is true (1) and no data has been transferred, then a system call interrupted by the signal *sig* will return -1 and *errno* will be set to **EINTR**.

If the *flag* argument is true (1) and data transfer has started, then the system call will be interrupted and will return the actual amount of data transferred.

## RETURN VALUE

The **siginterrupt**() function returns 0 on success. It returns -1 if the signal number *sig* is invalid, with *errno* set to indicate the error.

## ERRORS

- **EINVAL**

  The specified signal number is invalid.

## ATTRIBUTES

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

| | | |
| --- | --- | --- |
| **Interface** | **Attribute** | **Value** |
| **siginterrupt**() | Thread safety | MT-Unsafe const:sigintr |

## STANDARDS

POSIX.1-2008.

## HISTORY

4\.3BSD, POSIX.1-2001. Obsolete in POSIX.1-2008, recommending the use of [**sigaction**(2)](/sigaction/2.md) with the **SA\_RESTART** flag instead.

## SEE ALSO

[**signal**(2)](/signal/2.md)