$ virsh -c qemu:///system qemu-agent-command --domain sle-terraform-0 --cmd  '{ "execute": "guest-exec", "arguments": { "path": "ping" , "arg": ["-c", "1", "10.0.1.194"], "capture-output": true } }'
{"return":{"pid":1624}}

$ virsh -c qemu:///system qemu-agent-command --domain sle-terraform-0 --cmd '{ "execute": "guest-exec-status", "arguments": { "pid": 1624 } }'
{"return":{"exitcode":0,"out-data":"UElORyAxMC4wLjEuMTk0ICgxMC4wLjEuMTk0KSA1Nig4NCkgYnl0ZXMgb2YgZGF0YS4KNjQgYnl0ZXMgZnJvbSAxMC4wLjEuMTk0OiBpY21wX3NlcT0xIHR0bD02NCB0aW1lPTAuNDQ2IG1zCgotLS0gMTAuMC4xLjE5NCBwaW5nIHN0YXRpc3RpY3MgLS0tCjEgcGFja2V0cyB0cmFuc21pdHRlZCwgMSByZWNlaXZlZCwgMCUgcGFja2V0IGxvc3MsIHRpbWUgMG1zCnJ0dCBtaW4vYXZnL21heC9tZGV2ID0gMC40NDYvMC40NDYvMC40NDYvMC4wMDAgbXMK","exited":true}}


The output above is encoded in base64, and when decoding it, you get this:

PING 10.0.1.194 (10.0.1.194) 56(84) bytes of data.
64 bytes from 10.0.1.194: icmp_seq=1 ttl=64 time=0.446 ms

--- 10.0.1.194 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.446/0.446/0.446/0.000 ms