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STAT
!!!STAT
NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
CONFORMING TO
OTHER SYSTEMS
SEE ALSO
----
!!NAME


stat, fstat, lstat - get file status
!!SYNOPSIS


__#include __
#include __
#include __


__int stat(const char *__''file_name''__, struct stat
*__''buf''__);
int fstat(int__ ''filedes''__, struct stat
*__''buf''__);
int lstat(const char *__''file_name''__, struct stat
*__''buf''__);__
!!DESCRIPTION


These functions return information about the specified file.
You do not need any access rights to the file to get this
information but you need search rights to all directories
named in the path leading to the file.


__stat__ stats the file pointed to by ''file_name''
and fills in ''buf''.


__lstat__ is identical to __stat__, except in the case
of a symbolic link, where the link itself is stat-ed, not
the file that it refers to.


__fstat__ is identical to stat, only the open file
pointed to by ''filedes'' (as returned by open(2))
is statted in place of ''file_name''.


They all return a ''stat'' structure, which contains the
following fields:


struct stat {
dev_t         st_dev;      /* device */
ino_t         st_ino;      /* inode */
mode_t        st_mode;     /* protection */
nlink_t       st_nlink;    /* number of hard links */
uid_t         st_uid;      /* user ID of owner */
gid_t         st_gid;      /* group ID of owner */
dev_t         st_rdev;     /* device type (if inode device) */
off_t         st_size;     /* total size, in bytes */
unsigned long st_blksize;  /* blocksize for filesystem I/O */
unsigned long st_blocks;   /* number of blocks allocated */
time_t        st_atime;    /* time of last access */
time_t        st_mtime;    /* time of last modification */
time_t        st_ctime;    /* time of last change */
};


The value ''st_size'' gives the size of the file (if it
is a regular file or a symlink) in bytes. The size of a
symlink is the length of the pathname it contains, without
trailing NUL.


The value ''st_blocks'' gives the size of the file in
512-byte blocks. (This may be smaller than
''st_size''/512 e.g. when the file has holes.) The value
''st_blksize'' gives the
''


Not all of the Linux filesystems implement all of the time
fields. Some file system types allow mounting in such a way
that file accesses do not cause an update of the
''st_atime'' field. (See `noatime' in
mount(8).)


The field ''st_atime'' is changed by file accesses, e.g.
by exec(2), mknod(2), pipe(2),
utime(2) and read(2) (of more than zero
bytes). Other routines, like mmap(2), may or may not
update ''st_atime''.


The field ''st_mtime'' is changed by file modifications,
e.g. by mknod(2), truncate(2), utime(2)
and write(2) (of more than zero bytes). Moreover,
''st_mtime'' of a directory is changed by the creation or
deletion of files in that directory. The ''st_mtime''
field is ''not'' changed for changes in owner, group,
hard link count, or mode.


The field ''st_ctime'' is changed by writing or by
setting inode information (i.e., owner, group, link count,
mode, etc.).


The following POSIX macros are defined to check the file
type:


S_ISREG(m)


is it a regular file?


S_ISDIR(m)


directory?


S_ISCHR(m)


character device?


S_ISBLK(m)


block device?


S_ISFIFO(m)


fifo?


S_ISLNK(m)


symbolic link? (Not in POSIX.1-1996.)


S_ISSOCK(m)


socket? (Not in POSIX.1-1996.)


The following flags are defined for the ''st_mode''
field:


The set GID bit (S_ISGID) has several special uses: For a directory it indicates that BSD semantics is to be used for that directory: files created there inherit their group ID from the directory, not from the effective gid of the creating process, and directories created there will also get the S_ISGID bit set. For a file that does not have the group execution bit (S_IXGRP) set, it indicates mandatory file/record locking.


The `sticky' bit (S_ISVTX) on a directory means that a file
in that directory can be renamed or deleted only by the
owner of the file, by the owner of the directory, and by
root.
!!RETURN VALUE


On success, zero is returned. On error, -1 is returned, and
''errno'' is set appropriately.
!!ERRORS


__EBADF__


''filedes'' is bad.


__ENOENT__


A component of the path ''file_name'' does not exist, or
the path is an empty string.


__ENOTDIR__


A component of the path is not a directory.


__ELOOP__


Too many symbolic links encountered while traversing the
path.


__EFAULT__


Bad address.


__EACCES__


Permission denied.


__ENOMEM__


Out of memory (i.e. kernel memory).


__ENAMETOOLONG__


File name too long.
!!CONFORMING TO


The __stat__ and __fstat__ calls conform to SVr4,
SVID, POSIX, X/OPEN, BSD 4.3. The __lstat__ call conforms
to 4.3BSD and SVr4. SVr4 documents additional __fstat__
error conditions EINTR, ENOLINK, and EOVERFLOW. SVr4
documents additional __stat__ and __lstat__ error
conditions EACCES, EINTR, EMULTIHOP, ENOLINK, and EOVERFLOW.
Use of the ''st_blocks'' and ''st_blksize'' fields may
be less portable. (They were introduced in BSD. Are not
specified by POSIX. The interpretation differs between
systems, and possibly on a single system when NFS mounts are
involved.)


POSIX does not describe the S_IFMT, S_IFSOCK, S_IFLNK,
S_IFREG, S_IFBLK, S_IFDIR, S_IFCHR, S_IFIFO, S_ISVTX bits,
but instead demands the use of the macros S_ISDIR(), etc.
The S_ISLNK and S_ISSOCK macros are not in POSIX.1-1996, but
both will be in the next POSIX standard; the former is from
SVID 4v2, the latter from SUSv2.


Unix V7 (and later systems) had S_IREAD, S_IWRITE, S_IEXEC,
where POSIX prescribes the synonyms S_IRUSR, S_IWUSR,
S_IXUSR.
!!OTHER SYSTEMS


Values that have been (or are) in use on various
systems:


A sticky command appeared in Version 32V AT
!!SEE ALSO


chmod(2), chown(2), readlink(2),
utime(2)
----
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Last edited on Tuesday, June 4, 2002 12:23:48 am by "perry"
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