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

NAME         top

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

SYNOPSIS         top

       #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         top

       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
       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         top

       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 error.

ERRORS         top

       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         top

       For an explanation of the terms used in this section, see

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

CONFORMING TO         top

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

SEE ALSO         top

       lseek(2), fseeko(3)

COLOPHON         top

       This page is part of release 4.08 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

GNU                              2015-08-08                         FSEEK(3)