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stat(2)
stat(2) System Calls stat(2)
NAME
stat, lstat, fstat, fstatat - get file status
SYNOPSIS
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
int stat(const char *restrict path, struct stat *restrict buf);
int lstat(const char *restrict path, struct stat *restrict buf);
int fstat(int fildes, struct stat *buf);
int fstatat(int fildes, const char *path, struct stat *buf,
int flag);
DESCRIPTION
The stat() function obtains information about the file pointed to by
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.
The lstat() function obtains file attributes similar to stat(), except
when the named file is a symbolic link; in that case lstat() returns
information about the link, while stat() returns information about the
file the link references.
The fstat() function obtains information about an open file known by
the file descriptor fildes, obtained from a successful call to a func‐
tion such as open(2), creat(2), dup(2), fcntl(2), or pipe(2). If fildes
references a shared memory object, the system updates in the stat
structure pointed to by the buf argument only the st_uid, st_gid,
st_size, and st_mode fields, and only the S_IRUSR, S_IWUSR, S_IRGRP,
S_IWGRP, S_IROTH, and S_IWOTH file permission bits need be valid. The
system can update other fields and flags. The fstat() function updates
any pending time-related fields before writing to the stat structure.
The fstatat() function obtains file attributes similar to the stat(),
lstat(), and fstat() functions. If the path argument is a relative
path, it is resolved relative to the fildes argument rather than the
current working directory. If path is absolute, the fildes argument is
unused. If the fildes argument has the special value AT_FDCWD, relative
paths are resolved from the current working directory. If AT_SYM‐
LINK_NOFOLLOW is set in the flag argument, the function behaves like
lstat() and does not automatically follow symbolic links. See
fsattr(7). If _AT_TRIGGER is set in the flag argument and the vnode is
an autofs trigger mount point, the mount is performed and the function
returns the attributes of the root of the mounted filesystem.
The buf argument is a pointer to a stat structure into which informa‐
tion is placed concerning the file. A stat structure includes the fol‐
lowing members:
mode_t st_mode; /* File mode (see mknod(2)) */
ino_t st_ino; /* File serial number */
dev_t st_dev; /* ID of device containing */
/* a directory entry for this file */
dev_t st_rdev; /* ID of device */
/* This entry is defined only for */
/* char special or block special files */
nlink_t st_nlink; /* Number of links */
uid_t st_uid; /* User ID of the file's owner */
gid_t st_gid; /* Group ID of the file's group */
off_t st_size; /* File size in bytes */
timespec_t st_atim; /* Timestamp of last access */
timespec_t st_mtim; /* Timestamp of last data modification */
timespec_t st_ctim; /* Timestamp of last file status change */
/* Timestamps contain seconds and nanoseconds */
/* since 00:00:00 UTC, Jan. 1, 1970 */
long st_blksize; /* Preferred I/O block size */
blkcnt_t st_blocks; /* Number of 512 byte blocks allocated*/
char st_fstype[_ST_FSTYPSZ];
/* Null-terminated type of filesystem */
Descriptions of structure members are as follows:
st_mode The mode of the file as described for the mknod() function.
In addition to the modes described on the mknod(2) manual
page, the mode of a file can also be S_IFSOCK if the file
is a socket, S_IFDOOR if the file is a door, S_IFPORT if
the file is an event port, or S_IFLNK if the file is a sym‐
bolic link. S_IFLNK can be returned either by lstat() or by
fstatat() when the AT_SYMLINK_NOFOLLOW flag is set.
To check the type of a file, compare st_mode & S_IFMT
against the appropriate S_IF* macro value, or use the S_IS*
convenience macros defined in stat.h(3HEAD). To check the
access mode of a file, compare st_mode & S_IAMB against the
appropriate file permission bitmask macros defined in
stat.h(3HEAD).
st_ino This field uniquely identifies the file in a given file
system. The pair st_ino and st_dev uniquely identifies reg‐
ular files.
st_dev This field uniquely identifies the file system that con‐
tains the file. Its value may be used as input to the
ustat(2) function to determine more information about this
file system. No other meaning is associated with this
value.
st_rdev This field should be used only by administrative commands.
It is valid only for block special or character special
files and only has meaning on the system where the file was
configured.
st_nlink This field should be used only by administrative commands.
st_uid The user ID of the file's owner.
st_gid The group ID of the file's group.
st_size For regular files, this is the address of the end of the
file. For block special or character special, this is not
defined. See also pipe(2).
st_atim Timestamp when file data was last accessed. Some of the
functions that change this member are: creat(2), mknod(2),
pipe(2), utime(2), and read(2).
st_mtim Timestamp when data was last modified. Some of the func‐
tions that change this member are: creat(2), mknod(2),
pipe(2), utime(2), and write(2).
st_ctim Timestamp when file status was last changed. Some of the
functions that change this member are: chmod(2), chown(2),
creat(2), link(2), mknod(2), pipe(2), rename(2), unlink(2),
utime(2), and write(2).
Note -
For compatibility with earlier versions of this structure the macro
st_atime is defined to access the seconds component of the st_atim
timestamp. Similarly the macros st_mtime and st_ctime are defined to
provide access to the seconds components of the st_mtim and st_ctim
timestamps respectively.
st_blksize A hint as to the "best" unit size for I/O operations.
This field is not defined for block special or character
special files.
st_blocks The total number of physical blocks of size 512 bytes
actually allocated on disk. This field is not defined for
block special or character special files.
st_fstype A null-terminated string that uniquely identifies the
type of the filesystem that contains the file.
RETURN VALUES
Upon successful completion, 0 is returned. Otherwise, −1 is returned
and errno is set to indicate the error.
ERRORS
The stat(), fstat(), lstat(), and fstatat() functions will fail if:
EIO An error occurred while reading from the file system.
EOVERFLOW The file size in bytes or the number of blocks allocated
to the file or the file serial number cannot be repre‐
sented correctly in the structure pointed to by buf.
The stat(), lstat(), and fstatat() functions will fail if:
EACCES Search permission is denied for a component of the path
prefix.
EFAULT The buf or path argument points to an illegal address.
EINTR A signal was caught during the execution of the stat()
or lstat() function.
ELOOP A loop exists in symbolic links encountered during the
resolution of the path argument.
ENAMETOOLONG The length of the path argument exceeds {PATH_MAX}, or
the length of a path component exceeds {NAME_MAX} while
_POSIX_NO_TRUNC is in effect.
ENOENT A component of path does not name an existing file or
path is an empty string.
ENOLINK The path argument points to a remote machine and the
link to that machine is no longer active.
ENOTDIR A component of the path prefix is not a directory, or
the fildes argument does not refer to a valid directory
when given a non-null relative path.
The fstat() and fstatat() functions will fail if:
EBADF The fildes argument is not a valid open file descriptor. The
fildes argument to fstatat() can also have the valid value
of AT_FDCWD.
EFAULT The buf argument points to an illegal address.
EINTR A signal was caught during the execution of the fstat()
function.
ENOLINK The fildes argument points to a remote machine and the link
to that machine is no longer active.
The stat(), fstat(), and lstat() functions may fail if:
EOVERFLOW One of the members is too large to store in the stat
structure pointed to by buf.
The stat() and lstat() functions may fail if:
ELOOP More than {SYMLOOP_MAX} symbolic links were encountered
during the resolution of the path argument.
ENAMETOOLONG As a result of encountering a symbolic link in resolu‐
tion of the path argument, the length of the substi‐
tuted pathname strings exceeds {PATH_MAX}.
The stat() and fstatat() functions may fail if:
ENXIO The path argument names a character or block device special
file and the corresponding I/O device has been retired by the
fault management framework.
EXAMPLES
Example 1 Use stat() to obtain file status information.
The following example shows how to obtain file status information for a
file named /home/cnd/mod1. The structure variable buffer is defined for
the stat structure.
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
struct stat buffer;
int status;
...
status = stat("/home/cnd/mod1", &buffer);
Example 2 Use stat() to get directory information.
The following example fragment gets status information for each entry
in a directory. The call to the stat() function stores file information
in the stat structure pointed to by statbuf. The lines that follow the
stat() call format the fields in the stat structure for presentation
to the user of the program.
#include <sys/types.h>
#include <sys/stat.h>
#include <dirent.h>
#include <pwd.h>
#include <grp.h>
#include <time.h>
#include <locale.h>
#include <langinfo.h>
#include <stdio.h>
#include <stdint.h>
struct dirent *dp;
struct stat statbuf;
struct passwd *pwd;
struct group *grp;
struct tm *tm;
char datestring[256];
...
/* Loop through directory entries */
while ((dp = readdir(dir)) != NULL) {
/* Get entry's information. */
if (stat(dp->d_name, &statbuf) == -1)
continue;
/* Print out type, permissions, and number of links. */
printf("%10.10s", mode_to_string(statbuf.st_mode));
printf("%4d", statbuf.st_nlink);
/* Print out owners name if it is found using getpwuid(). */
if ((pwd = getpwuid(statbuf.st_uid)) != NULL)
printf(" %-8.8s", pwd->pw_name);
else
printf(" %-8d", statbuf.st_uid);
/* Print out group name if it's found using getgrgid(). */
if ((grp = getgrgid(statbuf.st_gid)) != NULL)
printf(" %-8.8s", grp->gr_name);
else
printf(" %-8d", statbuf.st_gid);
/* Print size of file. */
printf(" %9jd", (intmax_t)statbuf.st_size);
tm = localtime(&statbuf.st_mtime);
/* Get localized date string. */
strftime(datestring, sizeof(datestring), nl_langinfo(D_T_FMT), tm);
printf(" %s %s\n", datestring, dp->d_name);
}
Example 3 Use fstat() to obtain file status information.
The following example shows how to obtain file status information for a
file named /home/cnd/mod1. The structure variable buffer is defined for
the stat structure. The /home/cnd/mod1 file is opened with read/write
privileges and is passed to the open file descriptor fildes.
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
struct stat buffer;
int status;
...
fildes = open("/home/cnd/mod1", O_RDWR);
status = fstat(fildes, &buffer);
Example 4 Use lstat() to obtain symbolic link status information.
The following example shows how to obtain status information for a sym‐
bolic link named /modules/pass1. The structure variable buffer is
defined for the stat structure. If the path argument specified the
filename for the file pointed to by the symbolic link (/home/cnd/mod1),
the results of calling the function would be the same as those returned
by a call to the stat() function.
#include <sys/stat.h>
struct stat buffer;
int status;
...
status = lstat("/modules/pass1", &buffer);
USAGE
If chmod() or fchmod() is used to change the file group owner permis‐
sions on a file with non-trivial ACL entries, only the ACL mask is set
to the new permissions and the group owner permission bits in the
file's mode field (defined in mknod(2)) are unchanged. A non-trivial
ACL entry is one whose meaning cannot be represented in the file's mode
field alone. The new ACL mask permissions might change the effective
permissions for additional users and groups that have ACL entries on
the file.
The stat(), fstat(), and lstat() functions have transitional interfaces
for 64-bit file offsets. See lf64(7).
ATTRIBUTES
See attributes(7) for descriptions of the following attributes:
tab() box; cw(2.75i) |cw(2.75i) lw(2.75i) |lw(2.75i) ATTRIBUTE TYPEAT‐
TRIBUTE VALUE _ Interface StabilityCommitted _ MT-LevelAsync-Signal-
Safe _ StandardSee below.
See standards(7) for descriptions of the following standards:
tab() box; cw(2.2i) |cw(3.3i) lw(2.2i) |lw(3.3i) INTERFACESAPPLICABLE
STANDARDS _ T{
stat()
lstat()
fstat()
T}T{
POSIX.1-1990 through 2008,
SUS through SUSv4,
XPG1 through XPG7
T} _
fstatat()
T{
SUSv4,
XPG7
T}
SEE ALSO
access(2), chmod(2), chown(2), creat(2), link(2), mknod(2), pipe(2),
read(2), time(2), unlink(2), utime(2), write(2), fattach(3C),
stat.h(3HEAD), attributes(7), fsattr(7), lf64(7), standards(7)
NOTES
Some file systems additionally provide a file creation timestamp, in
addition to the timestamps described above. This timestamp is not
available through the interfaces described on this page, but must
instead be retrieved using the getattrat(3C) function as the A_CRTIME
system attribute.
For testing purposes only, the behavior of these interfaces can be
changed when used by a 32-bit programs on systems where the timestamps
will not fit into the st_atime, st_mtime, or st_ctime stat structure
fields. If this configuration line is present in /etc/system:
set stat_timestamp32 = 1
A ceiling value will be substituted for the timestamps which do not fit
in the returned stat structure fields, and no EOVERFLOW error will be
returned. This option allows a limited set of testing to be performed
on systems with an advanced date/time where some 32-bit programs may
still be in use. This option exists purely for testing purposes; some
parts of Oracle Solaris will not behave correctly when this is used on
systems with the date advanced past 03:14:07 UTC January 19, 2038. No
support calls will be taken on such issues.
HISTORY
The stat(), lstat(), and fstat() functions have been included in all
Sun and Oracle releases of Solaris.
The fstatat() function was added to Solaris in the Solaris 9 release.
Oracle Solaris 11.4 30 Apr 2020 stat(2)