FSEEK(3) Linux Programmer's Manual FSEEK(3)NAME
fgetpos, fseek, fsetpos, ftell, rewind - reposition a stream
int fseek(FILE *stream, long offset, int whence);
long ftell(FILE *stream);
void rewind(FILE *stream);
int fgetpos(FILE *stream, fpos_t *pos);
int fsetpos(FILE *stream, fpos_t *pos);
The fseek() function sets the file position indicator for the stream
pointed to by stream. The new position, measured in bytes, is obtained
by adding offset bytes to the position specified by whence. If whence
is set to SEEK_SET, SEEK_CUR, or SEEK_END, the offset is relative to
the start of the file, the current position indicator, or end-of-file,
respectively. A successful call to the fseek() function clears the
end-of-file indicator for the stream and undoes any effects of the
ungetc(3) function on the same stream.
The ftell() function obtains the current value of the file position
indicator for the stream pointed to by stream.
The rewind() function sets the file position indicator for the stream
pointed to by stream to the beginning of the file. It is equivalent
(void) fseek(stream, 0L, SEEK_SET)
except that the error indicator for the stream is also cleared (see
The fgetpos() and fsetpos() functions are alternate interfaces equiva‐
lent to ftell() and fseek() (with whence set to SEEK_SET), setting and
storing the current value of the file offset into or from the object
referenced by pos. On some non-UNIX systems, an fpos_t object may be a
complex object and these routines may be the only way to portably repo‐
sition a text stream.
The rewind() function returns no value. Upon successful completion,
fgetpos(), fseek(), fsetpos() return 0, and ftell() returns the current
offset. Otherwise, -1 is returned and errno is set to indicate the
EBADF The stream specified is not a seekable stream.
EINVAL The whence argument to fseek() was not SEEK_SET, SEEK_END, or
SEEK_CUR. Or: the resulting file offset would be negative.
The functions fgetpos(), fseek(), fsetpos(), and ftell() may also fail
and set errno for any of the errors specified for the routines
fflush(3), fstat(2), lseek(2), and malloc(3).
SEE ALSOlseek(2), fseeko(3)COLOPHON
This page is part of release 3.65 of the Linux man-pages project. A
description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
GNU 2014-04-02 FSEEK(3)