1.\" Copyright (c) 1990, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.Dd May 5, 2020 29.Dt STRDUP 3 30.Os 31.Sh NAME 32.Nm strdup , 33.Nm strdupa , 34.Nm strndup , 35.Nm strndupa 36.Nd save a copy of a string 37.Sh LIBRARY 38.Lb libc 39.Sh SYNOPSIS 40.In string.h 41.Ft char * 42.Fn strdup "const char *str" 43.Ft char * 44.Fn strdupa "const char *str" 45.Ft char * 46.Fn strndup "const char *str" "size_t len" 47.Ft char * 48.Fn strndupa "const char *str" "size_t len" 49.Sh DESCRIPTION 50The 51.Fn strdup 52function 53allocates sufficient memory for a copy 54of the string 55.Fa str , 56does the copy, and returns a pointer to it. 57The memory is allocated with 58.Xr malloc 3 59and should be released with 60.Xr free 3 61when no longer needed. 62.Pp 63The 64.Fn strndup 65function copies at most 66.Fa len 67characters from the string 68.Fa str 69always 70.Dv NUL 71terminating the copied string. 72.Pp 73The 74.Fn strdupa 75function is identical to 76.Fn strdup 77but allocates the memory with 78.Xr alloca 3 . 79Similarly, the 80.Fn strndupa 81function is identical to 82.Fn strndup , 83but allocates the memory with 84.Xr alloca 3 . 85.Sh RETURN VALUES 86If insufficient memory is available, NULL is returned and 87.Va errno 88is set to 89.Er ENOMEM . 90Otherwise, the 91.Fn strdup 92family of functions return a pointer to the copied string. 93.Sh SEE ALSO 94.Xr alloca 3 , 95.Xr free 3 , 96.Xr malloc 3 , 97.Xr wcsdup 3 98.Sh STANDARDS 99The 100.Fn strdup 101function is specified by 102.St -p1003.1-2001 . 103The 104.Fn strndup 105function is specified by 106.St -p1003.1-2008 . 107The 108.Fn strdupa 109and 110.Fn strndupa 111functions are extensions, 112taken from glibc. 113.Sh HISTORY 114The 115.Fn strdup 116function first appeared in 117.Bx 4.3 Reno . 118The 119.Fn strndup 120function was added in 121.Fx 7.2 . 122The 123.Fn strdupa 124and 125.Fn strndupa 126functions were added in 127.Fx 15.1 . 128