int fseek (stream, offset, ptrname)
long ftell (stream)
fseek undoes any effects of ungetc(3P).
rewind(stream) is equivalent to fseek(stream, 0L, 0).
After fseek or rewind, the next operation on an update file may be either input or output (see argument type for fopen(3P) ).
ftell returns the current value of the offset relative to the beginning of the file associated with the named stream. The offset is measured in bytes on PARASITE 1.0, PARASITE-FS 1.0, UNIX 3.0, and UNIX/RT; on some other systems, it is a magic cookie and is the only foolproof way to obtain an offset for fseek.