FSEEK(3)                                                     Linux Programmer's Manual                                                    FSEEK(3)

NAME

       fgetpos, fseek, fsetpos, ftell, rewind - reposition a stream

SYNOPSIS

       #include <stdio.h>

       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, const fpos_t *pos);

DESCRIPTION

       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
       to:

              (void) fseek(stream, 0L, SEEK_SET)

       except that the error indicator for the stream is also cleared (see clearerr(3)).

       The fgetpos() and fsetpos() functions are alternate interfaces equivalent 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 reposition a text stream.

RETURN VALUE

       The  rewind()  function returns no value.  Upon successful completion, fgetpos(), fseek(), fsetpos() return 0, and ftell() returns the cur-
       rent offset.  Otherwise, -1 is returned and errno is set to indicate the error.

ERRORS

       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).

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

       +----------------------------+---------------+---------+
       |Interface                   | Attribute     | Value   |
       +----------------------------+---------------+---------+
       |fseek(), ftell(), rewind(), | Thread safety | MT-Safe |
       |fgetpos(), fsetpos()        |               |         |
       +----------------------------+---------------+---------+

CONFORMING TO

       POSIX.1-2001, POSIX.1-2008, C89, C99.

SEE ALSO

       lseek(2), fseeko(3)

COLOPHON

       This  page is part of release 4.15 of the Linux man-pages project.  A description of the project, information about reporting bugs, and the
       latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.

GNU                                                                 2017-09-15                                                            FSEEK(3)