Lseek position in file lseek int pn long position int type os9 I$SEEK The read or write pointer for the open file with the path number, "pn", is positioned by lseek to the specified place in the file. The "type" indicates from where "position" is to be measured: if 0, from the beginning of the file, if 1, from the current location, or if 2, from the end of the file. Seeking to a location beyond the end of a file open for writing and then writing to it, creates a "hole" in the file which appears to be filled with zeros from the previous end to the position sought. The returned value is the resulting position in the file unless there is an error, so to find out the current position use lseek(pn,0l,1); The argument "position" must be a long integer. Constants should be explicitly made long by appending an "l", as above, and other types should be converted using a cast: e.g. lseek(pn,(long)pos,1); Notice also, that the return value from lseek is itself a long integer. -1 is returned if "pn" is a bad path number, or attempting to seek to a position before the beginning of a file. creat(), open(), Standard Library function "fseek"