lseek(2) [v7 man page]

LSEEK(2)							System Calls Manual							  LSEEK(2)

NAME

       lseek, tell - move read/write pointer

SYNOPSIS

       long lseek(fildes, offset, whence)
       long offset;

       long tell(fildes)

DESCRIPTION

       The file descriptor refers to a file open for reading or writing.  The read (resp. write) pointer for the file is set as follows:

	      If whence is 0, the pointer is set to offset bytes.

	      If whence is 1, the pointer is set to its current location plus offset.

	      If whence is 2, the pointer is set to the size of the file plus offset.

       The returned value is the resulting pointer location.

       The obsolete function tell(fildes) is identical to lseek(fildes, 0L, 1).

       Seeking far beyond the end of a file, then writing, creates a gap or `hole', which occupies no physical space and reads as zeros.

SEE ALSO

       open(2), creat(2), fseek(3)

DIAGNOSTICS

       -1 is returned for an undefined file descriptor, seek on a pipe, or seek to a position before the beginning of file.

BUGS

       Lseek is a no-op on character special files.

ASSEMBLER

       (lseek = 19.)
       (file descriptor in r0)
       sys lseek; offset1; offset2; whence

       Offset1 and offset2 are the high and low words of offset; r0 and r1 contain the pointer upon return.

																	  LSEEK(2)

LSEEK(2)							System Calls Manual							  LSEEK(2)

NAME

       lseek - move read/write pointer

SYNOPSIS

       #include <sys/types.h>
       #include <unistd.h>

       #define SEEK_SET  0     /* offset is absolute */
       #define SEEK_CUR  1     /* relative to current position */
       #define SEEK_END  2     /* relative to end of file */

       off_t lseek(int d, off_t offset, int whence)

DESCRIPTION

       The descriptor d refers to a file or device open for reading and/or writing.  Lseek sets the file pointer of d as follows:

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

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

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

       Upon  successful  completion, the resulting pointer location as measured in bytes from beginning of the file is returned.  Some devices are
       incapable of seeking.  The value of the pointer associated with such a device is undefined.

NOTES

       Seeking far beyond the end of a file, then writing, creates a gap or "hole", which occupies no physical space and reads as zeros.

RETURN VALUE

       Upon successful completion, the current file pointer value is returned.	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.

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

       [EINVAL]       Whence is not a proper value.

SEE ALSO

       fcntl(2), open(2).

BUGS

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

4th Berkeley Distribution					 February 24, 1986							  LSEEK(2)