This file is indexed.

/usr/include/err.h is in libc6-dev 2.23-0ubuntu10.

This file is owned by root:root, with mode 0o644.

The actual contents of the file can be viewed below.

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
/* 4.4BSD utility functions for error messages.
   Copyright (C) 1995-2016 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <http://www.gnu.org/licenses/>.  */

#ifndef	_ERR_H
#define	_ERR_H	1

#include <features.h>

#define	__need___va_list
#include <stdarg.h>
#ifndef	__GNUC_VA_LIST
# define __gnuc_va_list	__ptr_t
#endif

__BEGIN_DECLS

/* Print "program: ", FORMAT, ": ", the standard error string for errno,
   and a newline, on stderr.  */
extern void warn (const char *__format, ...)
     __attribute__ ((__format__ (__printf__, 1, 2)));
extern void vwarn (const char *__format, __gnuc_va_list)
     __attribute__ ((__format__ (__printf__, 1, 0)));

/* Likewise, but without ": " and the standard error string.  */
extern void warnx (const char *__format, ...)
     __attribute__ ((__format__ (__printf__, 1, 2)));
extern void vwarnx (const char *__format, __gnuc_va_list)
     __attribute__ ((__format__ (__printf__, 1, 0)));

/* Likewise, and then exit with STATUS.  */
extern void err (int __status, const char *__format, ...)
     __attribute__ ((__noreturn__, __format__ (__printf__, 2, 3)));
extern void verr (int __status, const char *__format, __gnuc_va_list)
     __attribute__ ((__noreturn__, __format__ (__printf__, 2, 0)));
extern void errx (int __status, const char *__format, ...)
     __attribute__ ((__noreturn__, __format__ (__printf__, 2, 3)));
extern void verrx (int __status, const char *, __gnuc_va_list)
     __attribute__ ((__noreturn__, __format__ (__printf__, 2, 0)));

__END_DECLS

#endif	/* err.h */