问题：
这是aws日志list-log-groups，输出是JSON格式，我需要grep第一个"arn"值。我该怎么做？
{
"logGroups": [
{
"logGroupName": "alla",
"creationTime": 1594638588652,
"metricFilterCount": 0,
"arn": "arn:aws:logs:us-east-1:12345678910:log-group:*:*",
"storedBytes": 0
},
{
"logGroupName": "mahi",
"creationTime": 1594638580461,
"metricFilterCount": 0,
"arn": "arn:aws:logs:us-east-1:12345678910:log-group:*:*",
"storedBytes": 0
}
]
}
答案1：
我最近发现了一个gron的软件。
gron <<'END_JSON'
{
"logGroups": [
{
"logGroupName": "alla",
"creationTime": 1594638588652,
"metricFilterCount": 0,
"arn": "arn:aws:logs:us-east-1:12345678910:log-group:*:*",
"storedBytes": 0
},
{
"logGroupName": "mahi",
"creationTime": 1594638580461,
"metricFilterCount": 0,
"arn": "arn:aws:logs:us-east-1:12345678910:log-group:*:*",
"storedBytes": 0
}
]
}
END_JSON
json = {};
json.logGroups = [];
json.logGroups[0] = {};
json.logGroups[0].arn = "arn:aws:logs:us-east-1:12345678910:log-group:*:*";
json.logGroups[0].creationTime = 1594638588652;
json.logGroups[0].logGroupName = "alla";
json.logGroups[0].metricFilterCount = 0;
json.logGroups[0].storedBytes = 0;
json.logGroups[1] = {};
json.logGroups[1].arn = "arn:aws:logs:us-east-1:12345678910:log-group:*:*";
json.logGroups[1].creationTime = 1594638580461;
json.logGroups[1].logGroupName = "mahi";
json.logGroups[1].metricFilterCount = 0;
json.logGroups[1].storedBytes = 0;
此工具将JSON表示法转换为易于抓取的逐行javascript。
$ arn=$(gron <<'END_JSON' | sed -En '/json.logGroups[0].arn/ s/^[^"]*"(.*)";$/1/p'
{
...
}
END_JSON
)
$ echo "$arn"
arn:aws:logs:us-east-1:12345678910:log-group:*:*
答案2：
使用jq：
aws logs list-log-groups | jq -r '.logGroups[0].arn'
输出：
arn:aws:logs:us-east-1:929815623526:log-group:alla:
可以从Universe存储库安装jq:
sudo apt install jq
最好使用jq来解析json，但是没法用jq，并且格式不会改变，则可以使用grep -P和head -n1:
aws logs list-log-groups | grep -Po '"arn": "K[^"]*' | head -n1
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