.\" $OpenBSD: stat.2,v 1.41 2014/08/22 23:05:15 krw Exp $ .\" .\" Copyright (c) 1980, 1991, 1993, 1994 .\" The Regents of the University of California. All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. Neither the name of the University nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" @(#)stat.2 8.3 (Berkeley) 4/19/94 .\" .Dd $Mdocdate: August 22 2014 $ .Dt STAT 2 .Os .Sh NAME .Nm stat , .Nm lstat , .Nm fstatat , .Nm fstat .Nd get file status .Sh SYNOPSIS .Fd #include .Ft int .Fn stat "const char *path" "struct stat *sb" .Ft int .Fn lstat "const char *path" "struct stat *sb" .Ft int .Fn fstat "int fd" "struct stat *sb" .Fd #include .Fd #include .Ft int .Fn fstatat "int fd" "const char *path" "struct stat *sb" "int flag" .Sh DESCRIPTION The .Fn stat function obtains information about the file pointed to by .Fa path . Read, write, or execute permission of the named file is not required, but all directories listed in the path name leading to the file must be searchable. .Pp The .Fn lstat function is identical to .Fn stat except when the named file is a symbolic link, in which case .Fn lstat returns information about the link itself, not the file the link references. .Pp The .Fn fstatat function is equivalent to either the .Fn stat or .Fn lstat function depending on the value of .Fa flag (see below), except that where .Fa path specifies a relative path, the file whose information is returned is determined relative to the directory associated with file descriptor .Fa fd instead of the current working directory. .Pp If .Fn fstatat is passed the special value .Dv AT_FDCWD (defined in .In fcntl.h ) in the .Fa fd parameter, the current working directory is used and the behavior is identical to a call to .Fn stat or .Fn lstat , depending on whether or not the .Dv AT_SYMLINK_NOFOLLOW bit is set in .Fa flag . .Pp The .Fa flag argument is the bitwise OR of zero or more of the following values: .Pp .Bl -tag -width AT_SYMLINK_NOFOLLOW -offset indent -compact .It Dv AT_SYMLINK_NOFOLLOW If .Fa path names a symbolic link, then the status of the symbolic link is returned. .El .Pp The .Fn fstat function obtains the same information about an open file known by the file descriptor .Fa fd . .Pp The .Fa sb argument is a pointer to a .Fn stat structure as defined by .In sys/stat.h (shown below) and into which information is placed concerning the file. .Bd -literal struct stat { dev_t st_dev; /* inode's device */ ino_t st_ino; /* inode's number */ mode_t st_mode; /* inode protection mode */ nlink_t st_nlink; /* number of hard links */ uid_t st_uid; /* user ID of the file's owner */ gid_t st_gid; /* group ID of the file's group */ dev_t st_rdev; /* device type */ struct timespec st_atim; /* time of last access */ struct timespec st_mtim; /* time of last data modification */ struct timespec st_ctim; /* time of last file status change */ off_t st_size; /* file size, in bytes */ blkcnt_t st_blocks; /* blocks allocated for file */ u_int32_t st_blksize;/* optimal blocksize for I/O */ u_int32_t st_flags; /* user defined flags for file */ u_int32_t st_gen; /* file generation number */ }; .Ed .Pp The time-related fields of .Li struct stat are represented in .Li struct timespec format, which has nanosecond precision. However, the actual precision is generally limited by the file system holding the file. The fields are as follows: .Bl -tag -width XXXst_mtim .It Fa st_atim Time when file data was last accessed. Set when the file system object was created and updated by the .Xr utimes 2 and .Xr read 2 system calls. .It Fa st_mtim Time when file data was last modified. Changed by the .Xr truncate 2 , .Xr utimes 2 , and .Xr write 2 system calls. For directories, changed by any system call that alters which files are in the directory, such as the .Xr unlink 2 , .Xr rename 2 , .Xr mkdir 2 , and .Xr symlink 2 system calls. .It Fa st_ctim Time when file status was last changed (inode data modification). Changed by the .Xr chmod 2 , .Xr chown 2 , .Xr link 2 , .Xr rename 2 , .Xr unlink 2 , .Xr utimes 2 , and .Xr write 2 system calls. .El .Pp In addition, all the time fields are set to the current time when a file system object is first created by the .Xr mkdir 2 , .Xr mkfifo 2 , .Xr mknod 2 , .Xr open 2 , and .Xr symlink 2 system calls. .Pp For compatibility with previous standards, .Fa st_atime , .Fa st_mtime , and .Fa st_ctime macros are provided that expand to the .Fa tv_secs member of their respective .Li struct timespec member. Deprecated macros are also provided for some transitional names: .Fa st_atimensec , .Fa st_mtimensec , .Fa st_ctimensec , .Fa st_atimespec , .Fa st_mtimespec , and .Fa st_ctimespec .Pp The size-related fields of the .Li struct stat are as follows: .Bl -tag -width XXXst_blksize .It Fa st_blksize The optimal I/O block size for the file. .It Fa st_blocks The actual number of blocks allocated for the file in 512-byte units. As short symbolic links are stored in the inode, this number may be zero. .El .Pp The status information word .Fa st_mode has the following bits: .Bd -literal -offset indent #define S_IFMT 0170000 /* type of file mask */ #define S_IFIFO 0010000 /* named pipe (fifo) */ #define S_IFCHR 0020000 /* character special */ #define S_IFDIR 0040000 /* directory */ #define S_IFBLK 0060000 /* block special */ #define S_IFREG 0100000 /* regular */ #define S_IFLNK 0120000 /* symbolic link */ #define S_IFSOCK 0140000 /* socket */ #define S_ISUID 0004000 /* set-user-ID on execution */ #define S_ISGID 0002000 /* set-group-ID on execution */ #define S_ISVTX 0001000 /* save swapped text even after use */ #define S_IRWXU 0000700 /* RWX mask for owner */ #define S_IRUSR 0000400 /* R for owner */ #define S_IWUSR 0000200 /* W for owner */ #define S_IXUSR 0000100 /* X for owner */ #define S_IRWXG 0000070 /* RWX mask for group */ #define S_IRGRP 0000040 /* R for group */ #define S_IWGRP 0000020 /* W for group */ #define S_IXGRP 0000010 /* X for group */ #define S_IRWXO 0000007 /* RWX mask for other */ #define S_IROTH 0000004 /* R for other */ #define S_IWOTH 0000002 /* W for other */ #define S_IXOTH 0000001 /* X for other */ .Ed .Pp The following macros test a file's type. If the file is of that type, a non-zero value is returned; otherwise, 0 is returned. .Bd -literal -offset indent S_ISBLK(st_mode m) /* block special */ S_ISCHR(st_mode m) /* char special */ S_ISDIR(st_mode m) /* directory */ S_ISFIFO(st_mode m) /* fifo */ S_ISLNK(st_mode m) /* symbolic link */ S_ISREG(st_mode m) /* regular file */ S_ISSOCK(st_mode m) /* socket */ .Ed .Pp For a list of access modes, see .In sys/stat.h , .Xr access 2 , and .Xr chmod 2 . .Sh RETURN VALUES Upon successful completion a value of 0 is returned. Otherwise, a value of \-1 is returned and .Va errno is set to indicate the error. .Sh ERRORS .Fn stat , .Fn lstat , and .Fn fstatat will fail if: .Bl -tag -width Er .It Bq Er ENOTDIR A component of the path prefix is not a directory. .It Bq Er ENAMETOOLONG A component of a pathname exceeded .Dv NAME_MAX characters, or an entire path name exceeded .Dv PATH_MAX characters. .It Bq Er ENOENT A component of .Em name does not exist or .Em name is the empty path. .It Bq Er EACCES Search permission is denied for a component of the path prefix. .It Bq Er ELOOP Too many symbolic links were encountered in translating the pathname. .It Bq Er EFAULT .Fa sb or .Em name points to an invalid address. .It Bq Er EIO An I/O error occurred while reading from or writing to the file system. .El .Pp Additionally, .Fn fstatat will fail if: .Bl -tag -width Er .It Bq Er EINVAL The value of the .Fa flag argument was neither zero nor .Dv AT_SYMLINK_NOFOLLOW . .It Bq Er EBADF The .Fa path argument specifies a relative path and the .Fa fd argument is neither .Dv AT_FDCWD nor a valid file descriptor. .It Bq Er ENOTDIR The .Fa path argument specifies a relative path and the .Fa fd argument is a valid file descriptor but it does not reference a directory. .It Bq Er EACCES The .Fa path argument specifies a relative path but search permission is denied for the directory which the .Fa fd file descriptor references. .El .Pp .Fn fstat will fail if: .Bl -tag -width Er .It Bq Er EBADF .Fa fd is not a valid open file descriptor. .It Bq Er EFAULT .Fa sb points to an invalid address. .It Bq Er EIO An I/O error occurred while reading from the file system. .El .Sh SEE ALSO .Xr chmod 2 , .Xr chown 2 , .Xr clock_gettime 2 , .Xr utimes 2 , .Xr symlink 7 .Sh STANDARDS Previous versions of the system used different types for the .Fa st_dev , .Fa st_uid , .Fa st_gid , .Fa st_rdev , .Fa st_size , .Fa st_blksize , and .Fa st_blocks fields. .Pp The .Fn fstat , .Fn fstatat , .Fn lstat , and .Fn stat functions are intended to conform to .St -p1003.1-2008 . .Sh HISTORY The .Fn stat and .Fn fstat system calls first appeared in .At v1 . The .In sys/stat.h header file and the .Vt "struct stat" were introduced in .At v7 . .Pp An .Fn lstat function call appeared in .Bx 4.2 . The .Fn fstatat function appeared in .Ox 5.0 . .Sh CAVEATS The file generation number, .Fa st_gen , is only available to the superuser. .Pp Certain programs written when the timestamps were just of type .Li time_t assumed that the members were consecutive (and could therefore be treated as an array and have their address passed directly to .Xr utime 3 ) . The transition to timestamps of type .Li struct timespec broke them irrevocably. .Sh BUGS Applying .Fn fstat to a pipe or socket fails to fill in a unique device and inode number pair. Applying .Fn fstat to a socket also fails to fill in the time fields.