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PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
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FSTAT(3P) POSIX Programmer's Manual FSTAT(3P)
This manual page is part of the POSIX Programmer's Manual. The
Linux implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior), or
the interface may not be implemented on Linux.
fstat — get file status
#include <sys/stat.h>
int fstat(int fildes, struct stat *buf);
The fstat() function shall obtain information about an open file
associated with the file descriptor fildes, and shall write it to
the area pointed to by buf.
If fildes references a shared memory object, the implementation
shall update in the stat structure pointed to by the buf argument
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 implementation may update
other fields and flags.
If fildes references a typed memory object, the implementation
shall update in the stat structure pointed to by the buf argument
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 implementation may update other
fields and flags.
The buf argument is a pointer to a stat structure, as defined in
<sys/stat.h>, into which information is placed concerning the
file.
For all other file types defined in this volume of POSIX.1‐2017,
the structure members st_mode, st_ino, st_dev, st_uid, st_gid,
st_atim, st_ctim, and st_mtim shall have meaningful values and the
value of the st_nlink member shall be set to the number of links
to the file.
An implementation that provides additional or alternative file
access control mechanisms may, under implementation-defined
conditions, cause fstat() to fail.
The fstat() function shall update any time-related fields (as
described in the Base Definitions volume of POSIX.1‐2017, Section
4.9, File Times Update), before writing into the stat structure.
Upon successful completion, 0 shall be returned. Otherwise, -1
shall be returned and errno set to indicate the error.
The fstat() function shall fail if:
EBADF The fildes argument is not a valid file descriptor.
EIO An I/O 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 represented
correctly in the structure pointed to by buf.
The fstat() function may fail if:
EOVERFLOW
One of the values is too large to store into the structure
pointed to by the buf argument.
The following sections are informative.
Obtaining 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);
None.
None.
None.
fstatat(3p)
The Base Definitions volume of POSIX.1‐2017, Section 4.9, File
Times Update, sys_stat.h(0p), sys_types.h(0p)
Portions of this text are reprinted and reproduced in electronic
form from IEEE Std 1003.1-2017, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The
Open Group Base Specifications Issue 7, 2018 Edition, Copyright
(C) 2018 by the Institute of Electrical and Electronics Engineers,
Inc and The Open Group. In the event of any discrepancy between
this version and the original IEEE and The Open Group Standard,
the original IEEE and The Open Group Standard is the referee
document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .
Any typographical or formatting errors that appear in this page
are most likely to have been introduced during the conversion of
the source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2017 FSTAT(3P)
Pages that refer to this page: sys_stat.h(0p), fstatat(3p), posix_typed_mem_get_info(3p), posix_typed_mem_open(3p), utime(3p)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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