On Fri, Dec 13, 2013 at 08:29:12AM +1100, Matthew Cengia wrote:
if $(ping -w 1 -c 1 -n 192.168.1.3 | grep -q "1 packets") ; then
You shouldn't have the $() here at all. They're unnecessary and cause confusion.
you're right. actually, it's worse than that...in that context, they're broken because command substitution - backticks or $(...)" - is only needed if you want to examine the output of a command/pipeline or assign it to a variable or similar. the code above won't work at all. dunno what i was thinking....too sleepy to think straight last night.
Further, don't bother checking ping's output with grep's return code. Check ping's return code instead: If ping -w1 -c1 -n 192.168.3.1 >/dev/null 2&>1; then
true also. i tend to use fping rather than ping to check if a host on the LAN is responding: fping is less verbose, has a handy -q (quiet) option to suppress output, and you can specify the timeout in milliseconds (default 500ms) rather than seconds. 50ms or even 10ms should be plenty of time for a host on the local ethernet to respond (i'd expect under a millisecond or a few ms at worst on a home 100baseT or gigabit network - of course that also depends on how fast the pinged host is and how heavy its workload is at the time). if fping -t 50 -q 192.168.3.1 ; then ... ; fi or fping -t 50 -q 192.168.3.1 && .... craig -- craig sanders <cas@taz.net.au>