fbbd9655e5
Renumber cluase 4 to 3, per what everybody else did when BSD granted them permission to remove clause 3. My insistance on keeping the same numbering for legal reasons is too pedantic, so give up on that point. Submitted by: Jan Schaumann <jschauma@stevens.edu> Pull Request: https://github.com/freebsd/freebsd/pull/96
437 lines
10 KiB
Groff
437 lines
10 KiB
Groff
.\" Copyright (c) 1980, 1991, 1993, 1994
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)stat.2 8.4 (Berkeley) 5/1/95
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.\" $FreeBSD$
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.\"
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.Dd January 14, 2016
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.Dt STAT 2
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.Os
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.Sh NAME
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.Nm stat ,
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.Nm lstat ,
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.Nm fstat ,
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.Nm fstatat
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.Nd get file status
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In sys/stat.h
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.Ft int
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.Fn stat "const char * restrict path" "struct stat * restrict sb"
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.Ft int
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.Fn lstat "const char * restrict path" "struct stat * restrict sb"
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.Ft int
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.Fn fstat "int fd" "struct stat *sb"
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.Ft int
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.Fn fstatat "int fd" "const char *path" "struct stat *buf" "int flag"
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.Sh DESCRIPTION
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The
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.Fn stat
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system call obtains information about the file pointed to by
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.Fa path .
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Read, write or execute
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permission of the named file is not required, but all directories
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listed in the path name leading to the file must be searchable.
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.Pp
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The
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.Fn lstat
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system call is like
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.Fn stat
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except in the case where the named file is a symbolic link,
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in which case
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.Fn lstat
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returns information about the link,
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while
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.Fn stat
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returns information about the file the link references.
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.Pp
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The
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.Fn fstat
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system call obtains the same information about an open file
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known by the file descriptor
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.Fa fd .
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.Pp
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The
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.Fn fstatat
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system call is equivalent to
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.Fn stat
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and
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.Fn lstat
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except in the case where the
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.Fa path
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specifies a relative path.
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In this case the status is retrieved from a file relative to
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the directory associated with the file descriptor
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.Fa fd
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instead of the current working directory.
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.Pp
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The values for the
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.Fa flag
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are constructed by a bitwise-inclusive OR of flags from the following list,
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defined in
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.In fcntl.h :
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.Bl -tag -width indent
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.It Dv AT_SYMLINK_NOFOLLOW
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If
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.Fa path
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names a symbolic link, the status of the symbolic link is returned.
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.El
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.Pp
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If
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.Fn fstatat
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is passed the special value
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.Dv AT_FDCWD
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in the
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.Fa fd
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parameter, the current working directory is used and the behavior is
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identical to a call to
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.Fn stat
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or
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.Fn lstat
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respectively, depending on whether or not the
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.Dv AT_SYMLINK_NOFOLLOW
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bit is set in
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.Fa flag .
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.Pp
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The
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.Fa sb
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argument is a pointer to a
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.Vt stat
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structure
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as defined by
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.In sys/stat.h
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and into which information is placed concerning the file.
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.Pp
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The fields of
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.Vt "struct stat"
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related to the file system are as follows:
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.Bl -tag -width ".Va st_nlink"
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.It Va st_dev
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The numeric ID of the device containing the file.
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.It Va st_ino
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The file's inode number.
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.It Va st_nlink
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The number of hard links to the file.
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.El
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.Pp
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The
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.Va st_dev
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and
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.Va st_ino
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fields together identify the file uniquely within the system.
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.Pp
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The time-related fields of
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.Vt "struct stat"
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are as follows:
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.Bl -tag -width ".Va st_birthtim"
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.It Va st_atim
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Time when file data last accessed.
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Changed by the
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.Xr mknod 2 ,
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.Xr utimes 2 ,
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.Xr read 2
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and
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.Xr readv 2
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system calls.
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.It Va st_mtim
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Time when file data last modified.
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Changed by the
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.Xr mkdir 2 ,
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.Xr mkfifo 2 ,
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.Xr mknod 2 ,
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.Xr utimes 2 ,
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.Xr write 2
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and
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.Xr writev 2
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system calls.
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.It Va st_ctim
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Time when file status was last changed (inode data modification).
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Changed by the
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.Xr chflags 2 ,
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.Xr chmod 2 ,
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.Xr chown 2 ,
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.Xr creat 2 ,
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.Xr link 2 ,
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.Xr mkdir 2 ,
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.Xr mkfifo 2 ,
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.Xr mknod 2 ,
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.Xr rename 2 ,
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.Xr rmdir 2 ,
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.Xr symlink 2 ,
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.Xr truncate 2 ,
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.Xr unlink 2 ,
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.Xr utimes 2 ,
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.Xr write 2
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and
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.Xr writev 2
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system calls.
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.It Va st_birthtim
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Time when the inode was created.
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.El
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.Pp
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The following time-related macros are defined for compatibility:
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.Bd -literal
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#define st_atime st_atim.tv_sec
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#define st_mtime st_mtim.tv_sec
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#define st_ctime st_ctim.tv_sec
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#ifndef _POSIX_SOURCE
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#define st_birthtime st_birthtim.tv_sec
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#endif
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#ifndef _POSIX_SOURCE
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#define st_atimespec st_atim
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#define st_mtimespec st_mtim
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#define st_ctimespec st_ctim
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#define st_birthtimespec st_birthtim
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#endif
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.Ed
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.Pp
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The size-related fields of the
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.Vt "struct stat"
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are as follows:
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.Bl -tag -width ".Va st_blksize"
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.It Va st_size
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The file size in bytes.
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.It Va st_blksize
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The optimal I/O block size for the file.
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.It Va st_blocks
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The actual number of blocks allocated for the file in 512-byte units.
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As short symbolic links are stored in the inode, this number may
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be zero.
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.El
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.Pp
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The access-related fields of
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.Vt "struct stat"
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are as follows:
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.Bl -tag -width ".Va st_mode"
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.It Va st_uid
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The user ID of the file's owner.
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.It Va st_gid
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The group ID of the file.
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.It Va st_mode
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Status of the file (see below).
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.El
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.Pp
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The status information word
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.Fa st_mode
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has the following bits:
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.Bd -literal
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#define S_IFMT 0170000 /* type of file mask */
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#define S_IFIFO 0010000 /* named pipe (fifo) */
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#define S_IFCHR 0020000 /* character special */
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#define S_IFDIR 0040000 /* directory */
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#define S_IFBLK 0060000 /* block special */
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#define S_IFREG 0100000 /* regular */
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#define S_IFLNK 0120000 /* symbolic link */
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#define S_IFSOCK 0140000 /* socket */
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#define S_IFWHT 0160000 /* whiteout */
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#define S_ISUID 0004000 /* set user id on execution */
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#define S_ISGID 0002000 /* set group id on execution */
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#define S_ISVTX 0001000 /* save swapped text even after use */
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#define S_IRWXU 0000700 /* RWX mask for owner */
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#define S_IRUSR 0000400 /* read permission, owner */
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#define S_IWUSR 0000200 /* write permission, owner */
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#define S_IXUSR 0000100 /* execute/search permission, owner */
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#define S_IRWXG 0000070 /* RWX mask for group */
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#define S_IRGRP 0000040 /* read permission, group */
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#define S_IWGRP 0000020 /* write permission, group */
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#define S_IXGRP 0000010 /* execute/search permission, group */
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#define S_IRWXO 0000007 /* RWX mask for other */
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#define S_IROTH 0000004 /* read permission, other */
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#define S_IWOTH 0000002 /* write permission, other */
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#define S_IXOTH 0000001 /* execute/search permission, other */
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.Ed
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.Pp
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For a list of access modes, see
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.In sys/stat.h ,
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.Xr access 2
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and
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.Xr chmod 2 .
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The following macros are available to test whether a
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.Va st_mode
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value passed in the
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.Fa m
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argument corresponds to a file of the specified type:
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.Bl -tag -width ".Fn S_ISFIFO m"
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.It Fn S_ISBLK m
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Test for a block special file.
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.It Fn S_ISCHR m
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Test for a character special file.
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.It Fn S_ISDIR m
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Test for a directory.
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.It Fn S_ISFIFO m
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Test for a pipe or FIFO special file.
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.It Fn S_ISLNK m
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Test for a symbolic link.
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.It Fn S_ISREG m
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Test for a regular file.
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.It Fn S_ISSOCK m
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Test for a socket.
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.It Fn S_ISWHT m
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Test for a whiteout.
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.El
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.Pp
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The macros evaluate to a non-zero value if the test is true
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or to the value 0 if the test is false.
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.Sh RETURN VALUES
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.Rv -std
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.Sh COMPATIBILITY
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Previous versions of the system used different types for the
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.Va st_dev ,
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.Va st_uid ,
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.Va st_gid ,
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.Va st_rdev ,
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.Va st_size ,
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.Va st_blksize
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and
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.Va st_blocks
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fields.
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.Sh ERRORS
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The
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.Fn stat
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and
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.Fn lstat
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system calls will fail if:
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.Bl -tag -width Er
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.It Bq Er EACCES
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Search permission is denied for a component of the path prefix.
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.It Bq Er EFAULT
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The
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.Fa sb
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or
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.Fa path
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argument
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points to an invalid address.
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.It Bq Er EIO
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An I/O error occurred while reading from or writing to the file system.
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.It Bq Er ELOOP
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Too many symbolic links were encountered in translating the pathname.
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.It Bq Er ENAMETOOLONG
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A component of a pathname exceeded 255 characters,
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or an entire path name exceeded 1023 characters.
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.It Bq Er ENOENT
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The named file does not exist.
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.It Bq Er ENOTDIR
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A component of the path prefix is not a directory.
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.It Bq Er EOVERFLOW
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The file size in bytes cannot be
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represented correctly in the structure pointed to by
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.Fa sb .
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.El
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.Pp
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The
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.Fn fstat
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system call will fail if:
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.Bl -tag -width Er
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.It Bq Er EBADF
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The
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.Fa fd
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argument
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is not a valid open file descriptor.
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.It Bq Er EFAULT
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The
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.Fa sb
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argument
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points to an invalid address.
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.It Bq Er EIO
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An I/O error occurred while reading from or writing to the file system.
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.It Bq Er EOVERFLOW
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The file size in bytes cannot be
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represented correctly in the structure pointed to by
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.Fa sb .
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.El
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.Pp
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In addition to the errors returned by the
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.Fn lstat ,
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the
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.Fn fstatat
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may fail if:
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.Bl -tag -width Er
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.It Bq Er EBADF
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The
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.Fa path
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argument does not specify an absolute path and the
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.Fa fd
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argument is neither
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.Dv AT_FDCWD
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nor a valid file descriptor open for searching.
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.It Bq Er EINVAL
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The value of the
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.Fa flag
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argument is not valid.
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.It Bq Er ENOTDIR
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The
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.Fa path
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argument is not an absolute path and
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.Fa fd
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is neither
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.Dv AT_FDCWD
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nor a file descriptor associated with a directory.
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.El
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.Sh SEE ALSO
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.Xr access 2 ,
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.Xr chmod 2 ,
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.Xr chown 2 ,
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.Xr fhstat 2 ,
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.Xr statfs 2 ,
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.Xr utimes 2 ,
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.Xr sticky 7 ,
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.Xr symlink 7
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.Sh STANDARDS
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The
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.Fn stat
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and
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.Fn fstat
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system calls are expected to conform to
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.St -p1003.1-90 .
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The
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.Fn fstatat
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system call follows The Open Group Extended API Set 2 specification.
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.Sh HISTORY
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The
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.Fn stat
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and
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.Fn fstat
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system calls appeared in
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.At v7 .
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The
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.Fn lstat
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system call appeared in
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.Bx 4.2 .
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The
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.Fn fstatat
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system call appeared in
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.Fx 8.0 .
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.Sh BUGS
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Applying
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.Fn fstat
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to a socket
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returns a zeroed buffer,
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except for the blocksize field,
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and a unique device and inode number.
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