mirror of https://github.com/mkerrisk/man-pages
86 lines
2.7 KiB
Groff
86 lines
2.7 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.\" manual page may be incorrect or out-of-date.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 Sat Jul 24 17:56:43 1993 by Rik Faith (faith@cs.unc.edu)
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.\" Added history, aeb, 980113.
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.\" 2005-05-05 mtk: added strcasestr()
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.\"
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.TH STRSTR 3 2005-04-05 "GNU" "Linux Programmer's Manual"
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.SH NAME
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strstr, strcasestr \- locate a substring
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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 *strstr(const char *" haystack ", const char *" needle );
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.sp
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.B #define _GNU_SOURCE
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.sp
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.B #include <string.h>
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.sp
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.BI "char *strcasestr(const char *" haystack ", const char *" needle );
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.fi
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.SH DESCRIPTION
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The
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.BR strstr ()
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function finds the first occurrence of the substring
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\fIneedle\fP in the string \fIhaystack\fP.
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The terminating \(aq\\0\(aq characters are not compared.
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The
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.BR strcasestr ()
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function is like
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.BR strstr (),
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but ignores the case of both arguments.
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.SH "RETURN VALUE"
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These functions return a pointer to the beginning of the
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substring, or NULL if the substring is not found.
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.SH "CONFORMING TO"
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The
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.BR strstr ()
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function conforms to C89 and C99.
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The
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.BR strcasestr ()
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function is a non-standard extension.
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.SH BUGS
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Early versions of Linux libc (like 4.5.26) would not allow
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an empty \fIneedle\fP argument for
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.BR strstr ().
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Later versions (like 4.6.27) work correctly,
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and return \fIhaystack\fP when \fIneedle\fP is empty.
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.SH "SEE ALSO"
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.BR index (3),
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.BR memchr (3),
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.BR rindex (3),
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.BR strchr (3),
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.BR strcasecmp (3),
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.BR strpbrk (3),
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.BR strsep (3),
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.BR strspn (3),
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.BR strtok (3),
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.BR wcsstr (3),
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.BR feature_test_macros (7)
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