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LSEEK(2)                    BSD System Calls Manual                   LSEEK(2)

NAME
     lseek -- reposition read/write file offset

SYNOPSIS
     #include <unistd.h>

     off_t
     lseek(int fildes, off_t offset, int whence);

DESCRIPTION
     The lseek() function repositions the offset of the file descriptor fildes to the argument offset,
     according to the directive whence.  The argument fildes must be an open file descriptor.  Lseek() repo-sitions repositions
     sitions the file pointer fildes as follows:

           If whence is SEEK_SET, the offset is set to offset bytes.

           If whence is SEEK_CUR, the offset is set to its current location plus offset bytes.

           If whence is SEEK_END, the offset is set to the size of the file plus offset bytes.

     The lseek() function allows the file offset to be set beyond the end of the existing end-of-file of the
     file. If data is later written at this point, subsequent reads of the data in the gap return bytes of
     zeros (until data is actually written into the gap).

     Some devices are incapable of seeking.  The value of the pointer associated with such a device is unde-fined. undefined.
     fined.

RETURN VALUES
     Upon successful completion, lseek() returns the resulting offset location as measured in bytes from the
     beginning of the file.  Otherwise, a value of -1 is returned and errno is set to indicate the error.

ERRORS
     Lseek() will fail and the file pointer will remain unchanged if:

     [EBADF]            Fildes is not an open file descriptor.

     [EINVAL]           Whence is not a proper value.

     [EINVAL]           The seek location (calculated from offset and whence) is negative.

     [EOVERFLOW]        The seek location is too large to be stored in an object of type off_t.

     [ESPIPE]           Fildes is associated with a pipe, socket, or FIFO.

SEE ALSO
     dup(2), open(2)

BUGS
     This document's use of whence is incorrect English, but is maintained for historical reasons.

STANDARDS
     The lseek() function conforms to IEEE Std 1003.1-1988 (``POSIX.1'').

4th Berkeley Distribution       April 19, 1994       4th Berkeley Distribution

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