$ export AWS_ACCESS_KEY_ID='...'
$ export AWS_SECRET_ACCESS_KEY='...'
$ export AWS_REGION='us-east-1'
$ grabeni grab eni-xxxxxx --instanceid i-xxxxxxd # attach eni-xxxxxx to EC2 instance where grabeni runs if instanceid option is skipped

$ grabeni ls
ID            NAME    STATUS      PRIVATE DNS NAME                              PRIVATE IP  AZ              DEVICE INDEX    INSTANCE ID INSTANCE NAME
eni-00000000  eni01   in-use      ip-10-0-0-100.ap-northeast-1.compute.internal 10.0.0.100  ap-northeast-1b 0   i-00000000  instance01
eni-11111111  eni02   available   ip-10-0-0-10.ap-northeast-1.compute.internal	10.0.0.10   ap-northeast-1c -1
eni-22222222  eni03   avaolable   ip-10-0-0-11.ap-northeast-1.compute.internal	10.0.0.11   ap-northeast-1c 1
$ grabeni status eni-2222222
ID            NAME    STATUS      PRIVATE DNS NAME                              PRIVATE IP  AZ              DEVICE INDEX    INSTANCE ID INSTANCE NAME
eni-22222222  eni03   avaolable   ip-10-0-0-11.ap-northeast-1.compute.internal	10.0.0.11   ap-northeast-1c 1
$ grabeni grab eni-2222222
--> Detaching:    eni-2222222
--> Attaching:    eni-2222222
eni eni-2222222 attached to instance i-xxxxxx

$ brew tap yuuki/grabeni
$ brew install grabeni

 $ go get github.com/yuuki/grabeni
 $ go install github.com/yuuki/grabeni/...