---
name: "strdup"
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/strdup"
---

# strdup(3)

string duplicate

## NAME

strdup - string duplicate

## LIBRARY

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

## SYNOPSIS

```
#include <string.h>
```

**char \*strdup(const char \****s***);**

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

**strdup**():

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

## DESCRIPTION

The **strdup**() function returns a pointer to a new string which is a duplicate of the string *s*. Memory for the new string is obtained with [**malloc**(3)](/malloc/3.md), and can be freed with [**free**(3)](/free/3.md).

## RETURN VALUE

On success, the **strdup**() function returns a pointer to the duplicated string. It returns NULL if insufficient memory was available, with *errno* set to indicate the error.

## ERRORS

See [**malloc**(3)](/malloc/3.md).

## ATTRIBUTES

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

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

## STANDARDS

POSIX.1-2008.

## HISTORY

SVr4, 4.3BSD-Reno, POSIX.1-2001.

## SEE ALSO

[**malloc**(3)](/malloc/3.md), [**string**(3)](/string/3.md), [**strdupa**(3)](/strdupa/3.md), [**wcsdup**(3)](/wcsdup/3.md)