I believe the && and || merely looks at output. For instance, if an error occurs, something is output to standard error. For example: $> ps aux | grep 'mysqld' | ( grep -v 'grep' && echo "MySQL is running" ) || echo "MySQL is not running!" and $> cat /var/log/messages 1>/dev/null || echo "Hey! You're not root!" Timothy On Tue, 14 Nov 2000, David Christian wrote: > > dopp at acm.cs.umn.edu wrote: > > > > > > On Mon, Nov 13, 2000 at 11:46:17AM -0600, Kent Schumacher wrote: > > > > I typically string 3 or four servers coupled by &&'s in case one of > > > > the servers is down. For example... > > > > > > > > ntpdate time.nist.gov && ntpdate for.a.good.time.call.gov && ntpdate > time.enough.org > > > > > Aren't error codes returned as numbers other than 0 and a regular exit a 0? > > If that's the case, and 0 is treated as false, then you *do* want to use && > for this. --------------------------------------------------------------------- Timothy Houck thouck at thouck.com www.thouck.com