Programming Perl, 4th Edition

close

close FILEHANDLE
close

This function closes the file, socket, or pipe associated with FILEHANDLE after flushing any IO buffers. It closes the currently selected filehandle if the argument is omitted. It returns true if the close is successful, false otherwise. You don’t have to close FILEHANDLE if you are immediately going to do another open on it, since the next open will close it for you, but then you would miss any error that occurred. (See open.) However, an explicit close on an input file resets the line counter ($.); the implicit close done by open does not.

FILEHANDLE may be an expression whose value can be used as an indirect filehandle (either the real filehandle name or a reference to anything that can be interpreted as a filehandle object).

If the filehandle came from a piped open, close returns false if any underlying syscall fails or if the program at the other end of the pipe exited with nonzero status. In the latter case, the close forces $! ($OS_ERROR) to zero. So if a close on a pipe returns a nonzero status, check $! to determine whether the problem was with the pipe itself (nonzero value) or with the program at the other end (zero value). In either event, $? ...