The tell() function obtains the current value of the file-position indicator for the file descriptor fd.

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.

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.

The tell() function is equivalent to lseek(fd, 0, SEEK_CUR).

See attributes(5) for descriptions of the following attributes:

lseek(2), attributes(5)