Can someone tell the reason why the following code fails, returning error Filed to reopen open(): Resource temporarily unavailable .... while ( ( fd = open( "/dev/ttyS0", O_RDWR ) ) < 0 ) { if ( errno != EINTR ) { printf( "Filed to open\n" ); perror( "open()" ); exit( 1 ); } } ..... close( fd ); When I connect two PCs with serial line (rs232, between /dev/ttyS0 and COM2(Win2k)), and run a java application that opens a serial port connection at the other end and just tries to read data from line. Im using the following gcc version gcc version 2.96 20000731 (Red Hat Linux 7.0) __________________________________ Do you Yahoo!? Yahoo! SiteBuilder - Free, easy-to-use web site design software http://sitebuilder.yahoo.com