On Fri, May 23, 2008 at 06:02:29PM +0200, Mihai T. Lazarescu wrote: > On Fri, May 23, 2008 at 08:41:19AM -0700, Scott McClanahan wrote: > > 1.1.1.1 foo > > 10.10.10.10 bar bar2 > > 100.100.100.100 foobar foobar2 foobar3 > > == After == > > 1.1.1.1 foo.contoso.com > > 10.10.10.10 bar.contoso.com bar2 > > 100.100.100.100 foobar.contoso.com foobar2 foobar3 > > > > Any advice on how to pull this off? Thanks. > > sed 's/ /.contoso.com ' That works because we've explicity been told <ip address> <tab> <short hostname> <space> <short hostname alias> so the first space is a good place to switch. More generally, if there's possibly multiple spaces or tabs in multiple places this might work: sed 's/^\([^ ]*[ ]*[^ ]*\)\([ ]*.*\)$/\1.contoso.com\2/' (where there's a space *and* a TAB inside each of the [ ] ) -- rgds Stephen