mirror of https://github.com/mkerrisk/man-pages
109 lines
3.1 KiB
Groff
109 lines
3.1 KiB
Groff
.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
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.\"
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\"
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.\" References consulted:
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.\" Linux libc source code
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.\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
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.\" 386BSD man pages
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.\" Modified Sun Jul 25 10:41:34 1993 by Rik Faith (faith@cs.unc.edu)
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.\" Modified Wed Oct 17 01:12:26 2001 by John Levon <moz@compsoc.man.ac.uk>
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.TH STRDUP 3 2007-07-26 "GNU" "Linux Programmer's Manual"
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.SH NAME
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strdup, strndup, strdupa, strndupa \- duplicate a string
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.SH SYNOPSIS
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.nf
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.B #include <string.h>
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.sp
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.BI "char *strdup(const char *" s );
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.sp
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.BI "char *strndup(const char *" s ", size_t " n );
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.br
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.BI "char *strdupa(const char *" s );
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.br
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.BI "char *strndupa(const char *" s ", size_t " n );
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.fi
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.sp
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.in -4n
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Feature Test Macro Requirements for glibc (see
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.BR feature_test_macros (7)):
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.in
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.sp
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.BR strdup ():
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_SVID_SOURCE || _BSD_SOURCE || _XOPEN_SOURCE\ >=\ 500
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.br
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.BR strndup (),
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.BR strdupa (),
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.BR strndupa ():
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_GNU_SOURCE
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.SH DESCRIPTION
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The
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.BR strdup ()
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function returns a pointer to a new string which
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is a duplicate of the string \fIs\fP.
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Memory for the new string is
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obtained with
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.BR malloc (3),
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and can be freed with
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.BR free (3).
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The
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.BR strndup ()
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function is similar, but only copies at most
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\fIn\fP characters.
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If \fIs\fP is longer than \fIn\fP, only \fIn\fP
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characters are copied, and a terminating null byte (\(aq\\0\(aq) is added.
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.BR strdupa ()
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and
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.BR strndupa ()
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are similar, but use
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.BR alloca (3)
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to allocate the buffer.
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They are only available when using the GNU
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GCC suite, and suffer from the same limitations described in
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.BR alloca (3).
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.SH "RETURN VALUE"
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The
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.BR strdup ()
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function returns a pointer to the duplicated
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string, or NULL if insufficient memory was available.
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.SH ERRORS
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.TP
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.B ENOMEM
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Insufficient memory available to allocate duplicate string.
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.SH "CONFORMING TO"
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.\" 4.3BSD-Reno, not (first) 4.3BSD.
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.BR strdup ()
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conforms to SVr4, 4.3BSD, POSIX.1-2001.
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.BR strndup (),
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.BR strdupa (),
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and
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.BR strndupa ()
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are GNU extensions.
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.SH "SEE ALSO"
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.BR alloca (3),
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.BR calloc (3),
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.BR free (3),
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.BR malloc (3),
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.BR realloc (3),
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.BR wcsdup (3)
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