1130b656e5
This will make a number of things easier in the future, as well as (finally!) avoiding the Id-smashing problem which has plagued developers for so long. Boy, I'm glad we're not using sup anymore. This update would have been insane otherwise.
302 lines
8.7 KiB
Groff
302 lines
8.7 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. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. 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 8.3 (Berkeley) 4/19/94
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.\" $FreeBSD$
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.\"
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.Dd April 19, 1994
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.Dt STAT 2
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.Os BSD 4
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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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.Nd get file status
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.Sh SYNOPSIS
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.Fd #include <sys/types.h>
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.Fd #include <sys/stat.h>
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.Ft int
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.Fn stat "const char *path" "struct stat *sb"
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.Ft int
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.Fn lstat "const char *path" "struct stat *sb"
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.Ft int
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.Fn fstat "int fd" "struct stat *sb"
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.Sh DESCRIPTION
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The
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.Fn stat
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function 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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.Fn Lstat
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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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Unlike other filesystem objects,
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symbolic links do not have an owner, group, access mode, times, etc.
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Instead, these attributes are taken from the directory that
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contains the link.
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The only attributes returned from an
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.Fn lstat
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that refer to the symbolic link itself are the file type (S_IFLNK),
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size, blocks, and link count (always 1).
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.Pp
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The
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.Fn fstat
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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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.Fa sb
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argument is a pointer to a
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.Fn stat
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structure
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as defined by
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.Aq Pa sys/stat.h
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(shown below)
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and into which information is placed concerning the file.
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.Bd -literal
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struct stat {
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dev_t st_dev; /* inode's device */
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ino_t st_ino; /* inode's number */
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mode_t st_mode; /* inode protection mode */
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nlink_t st_nlink; /* number of hard links */
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uid_t st_uid; /* user ID of the file's owner */
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gid_t st_gid; /* group ID of the file's group */
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dev_t st_rdev; /* device type */
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#ifndef _POSIX_SOURCE
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struct timespec st_atimespec; /* time of last access */
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struct timespec st_mtimespec; /* time of last data modification */
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struct timespec st_ctimespec; /* time of last file status change */
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#else
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time_t st_atime; /* time of last access */
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long st_atimensec; /* nsec of last access */
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time_t st_mtime; /* time of last data modification */
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long st_mtimensec; /* nsec of last data modification */
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time_t st_ctime; /* time of last file status change */
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long st_ctimensec; /* nsec of last file status change */
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#endif
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off_t st_size; /* file size, in bytes */
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quad_t st_blocks; /* blocks allocated for file */
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u_long st_blksize; /* optimal blocksize for I/O */
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u_long st_flags; /* user defined flags for file */
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u_long st_gen; /* file generation number */
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};
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.Ed
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.Pp
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The time-related fields of
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.Fa struct stat
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are as follows:
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.Bl -tag -width XXXst_mtime
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.It st_atime
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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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and
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.Xr read 2
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system calls.
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.It st_mtime
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Time when file data last modified.
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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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and
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.Xr write 2
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system calls.
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.It st_ctime
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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 chmod 2 ,
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.Xr chown 2 ,
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.Xr link 2 ,
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.Xr mknod 2 ,
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.Xr rename 2 ,
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.Xr unlink 2 ,
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.Xr utimes 2
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and
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.Xr write 2
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system calls.
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.El
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.Pp
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If
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.Dv _POSIX_SOURCE
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is not defined, the time-related fields are defined as:
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.Bd -literal
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#ifndef _POSIX_SOURCE
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#define st_atime st_atimespec.tv_sec
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#define st_mtime st_mtimespec.tv_sec
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#define st_ctime st_ctimespec.tv_sec
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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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.Fa struct stat
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are as follows:
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.Bl -tag -width XXXst_blksize
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.It st_blksize
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The optimal I/O block size for the file.
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.It 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 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 */
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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_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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.Ed
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.Pp
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For a list of access modes, see
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.Aq Pa 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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.Sh RETURN VALUES
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Upon successful completion a value of 0 is returned.
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Otherwise, a value of -1 is returned and
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.Va errno
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is set to indicate the error.
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.Sh COMPATIBILITY
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Previous versions of the system used different types for the
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.Li st_dev ,
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.Li st_uid ,
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.Li st_gid ,
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.Li st_rdev ,
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.Li st_size ,
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.Li st_blksize
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and
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.Li st_blocks
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fields.
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.Sh ERRORS
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.Fn Stat
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and
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.Fn lstat
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will fail if:
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.Bl -tag -width ENAMETOOLONGAA
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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 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 EACCES
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Search permission is denied for a component of the path prefix.
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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 EFAULT
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.Fa Sb
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or
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.Em name
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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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.El
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.Pp
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.Bl -tag -width [EFAULT]
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.Fn Fstat
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will fail if:
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.It Bq Er EBADF
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.Fa fd
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is not a valid open file descriptor.
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.It Bq Er EFAULT
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.Fa Sb
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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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.El
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.Sh CAVEAT
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The fields in the stat structure currently marked
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.Fa st_spare1 ,
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.Fa st_spare2 ,
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and
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.Fa st_spare3
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are present in preparation for inode time stamps expanding
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to 64 bits. This, however, can break certain programs that
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depend on the time stamps being contiguous (in calls to
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.Xr utimes 2 ) .
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.Sh SEE ALSO
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.Xr chmod 2 ,
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.Xr chown 2 ,
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.Xr utimes 2 ,
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.Xr symlink 7
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.Sh BUGS
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Applying
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.Fn fstat
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to a socket (and thus to a pipe)
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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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.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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function calls are expected to conform to
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.St -p1003.1-90 .
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.Sh HISTORY
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A
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.Fn stat
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and a
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.Fn fstat
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function call appeared in
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.At v7 .
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A
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.Fn lstat
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function call appeared in
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.Bx 4.2 .
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