Run command after full start

[Centaurus99]

Sometimes the first packet may be dropped since the early run. Log may like this:

2024-04-25T08:24:02.739274Z  INFO left_ns: rattan_cli: Running RATTAN_BASE="192.168.12.49" "/usr/bin/env" "./ping.sh" "5" "$RATTAN_BASE"
Server IP: 192.168.12.49
Running
PING 192.168.12.49 (192.168.12.49) 56(84) bytes of data.
64 bytes from 192.168.12.49: icmp_seq=2 ttl=64 time=0.245 ms
64 bytes from 192.168.12.49: icmp_seq=3 ttl=64 time=0.312 ms
64 bytes from 192.168.12.49: icmp_seq=4 ttl=64 time=0.330 ms
64 bytes from 192.168.12.49: icmp_seq=5 ttl=64 time=0.188 ms

--- 192.168.12.49 ping statistics ---
5 packets transmitted, 4 received, 20% packet loss, time 4085ms
rtt min/avg/max/mdev = 0.188/0.268/0.330/0.056 ms

We can use a atomic u8 to trace how many devices are fully started.