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tell(3c) [sunos man page]

tell(3C)						   Standard C Library Functions 						  tell(3C)

NAME
tell - return a file offset for a file descriptor SYNOPSIS
#include <unistd.h> off_t tell(int fd); DESCRIPTION
The tell() function obtains the current value of the file-position indicator for the file descriptor fd. RETURN VALUES
Upon successful completion, tell() returns the current value of the file-position indicator for fd measured in bytes from the beginning of the file. Otherwise, it returns -1 and sets errno to indicate the error. ERRORS
The tell() function will fail if: EBADF The file descriptor fd is not an open file descriptor. EOVERFLOW The current file offset cannot be represented correctly in an object of type off_t. ESPIPE The file descriptor fd is associated with a pipe or FIFO. USAGE
The tell() function is equivalent to lseek(fd, 0, SEEK_CUR). ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |MT-Level |MT-Safe | +-----------------------------+-----------------------------+ SEE ALSO
lseek(2), attributes(5) SunOS 5.10 28 Jan 1998 tell(3C)

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lseek(2)							   System Calls 							  lseek(2)

NAME
lseek - move read/write file pointer SYNOPSIS
#include <sys/types.h> #include <unistd.h> off_t lseek(int fildes, off_t offset, int whence); DESCRIPTION
The lseek() function sets the file pointer associated with the open file descriptor specified by fildes as follows: o If whence is SEEK_SET, the pointer is set to offset bytes. o If whence is SEEK_CUR, the pointer is set to its current location plus offset. o If whence is SEEK_END, the pointer is set to the size of the file plus offset. The symbolic constants SEEK_SET, SEEK_CUR, and SEEK_END are defined in the header <unistd.h>. Some devices are incapable of seeking. The value of the file pointer associated with such a device is undefined. The lseek() function allows the file pointer to be set beyond the existing data in the file. If data are later written at this point, sub- sequent reads in the gap between the previous end of data and the newly written data will return bytes of value 0 until data are written into the gap. If fildes is a remote file descriptor and offset is negative, lseek() returns the file pointer even if it is negative. The lseek() func- tion will not, by itself, extend the size of a file. If fildes refers to a shared memory object, lseek() behaves as if fildes referred to a regular file. RETURN VALUES
Upon successful completion, the resulting offset, as measured in bytes from the beginning of the file, is returned. Otherwise, (off_t)-1 is returned, the file offset remains unchanged, and errno is set to indicate the error. ERRORS
The lseek() function will fail if: EBADF The fildes argument is not an open file descriptor. EINVAL The whence argument is not SEEK_SET, SEEK_CUR, or SEEK_END; or the fildes argument is not a remote file descriptor and the resulting file pointer would be negative. EOVERFLOW The resulting file offset would be a value which cannot be represented correctly in an object of type off_t for regular files. ESPIPE The fildes argument is associated with a pipe, a FIFO, or a socket. USAGE
The lseek() function has a transitional interface for 64-bit file offsets. See lf64(5). In multithreaded applications, using lseek() in conjunction with a read(2) or write(2) call on a file descriptor shared by more than one thread is not an atomic operation. To ensure atomicity, use pread() or pwrite(). ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ |MT-Level |Async-Signal-Safe | +-----------------------------+-----------------------------+ SEE ALSO
creat(2), dup(2), fcntl(2), open(2), read(2), write(2), attributes(5), lf64(5), standards(5) SunOS 5.10 17 Apr 2002 lseek(2)
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