# 允许某个请求者操作 - ArnLike/ArnLikeIfExists

### ArnLike

`ArnLike` compares an ARN in a request to a list of ARN patterns in your policy. The policy values can include asterisks (\*) to match multiple characters and question marks (?) to match a single character within an ARN segement. Wildcards cannot be used to span ARN segment, so the partition, service, region, account, and resource must all be present in your policy value, even if they are all wildcards. The comparision is case sensitive.

To match a request, the context key must exist in the request and must match at least one of the ARN patterns in your policy.

You can use policy variables in the value of this operator.

#### ArnLike in an <mark style="color:green;">Allow</mark> Statement

<table data-full-width="true"><thead><tr><th width="408">Policy Condition</th><th>Request Context</th><th>Result</th></tr></thead><tbody><tr><td><pre><code>"ArnLike": {
  "aws:PrincipalArn": [
    "arn:aws:iam::*:role/*",
    "arn:aws:ec2:*:*:instance/i-?????"
  ]
}
</code></pre></td><td><code>aws:PrincipalArn: null</code></td><td><img src="https://iam.cloudcopilot.io/_astro/unknown.4jslFilM_ZFyvUV.svg" alt="Not Allowed"> Not AllowedStatement does not apply</td></tr><tr><td><pre><code>"ArnLike": {
  "aws:PrincipalArn": [
    "arn:aws:iam::*:role/*",
    "arn:aws:ec2:*:*:instance/i-?????"
  ]
}
</code></pre></td><td><code>aws:PrincipalArn:</code><br>   <code>arn:aws:iam::123456789012:role/AdminRole</code></td><td><img src="https://iam.cloudcopilot.io/_astro/allow.BKwnWDMp_Z2m9B7U.svg" alt="Allowed"> AllowedAssuming no explicit Deny elsewhere</td></tr><tr><td><pre><code>"ArnLike": {
  "aws:PrincipalArn": [
    "arn:aws:iam::*:role/*",
    "arn:aws:ec2:*:*:instance/i-?????"
  ]
}
</code></pre></td><td><code>aws:PrincipalArn:</code><br>   <code>arn:aws:iam::123456789012:user/User</code></td><td><img src="https://iam.cloudcopilot.io/_astro/unknown.4jslFilM_ZFyvUV.svg" alt="Not Allowed"> Not AllowedStatement does not apply</td></tr></tbody></table>

### ArnLikeIfExists

`ArnLikeIfExists` compares an ARN in a request to a list of ARN patterns in your policy. The policy values can include asterisks (\*) to match multiple characters and question marks (?) to match a single character within an ARN segement. Wildcards cannot be used to span ARN segment, so the partition, service, region, account, and resource must all be present in your policy value, even if they are all wildcards. The comparision is case sensitive.

To match a request, the context key can be absent, but if present it must match at least one of the ARN patterns in your policy.

You can use policy variables in the value of this operator.

#### ArnLikeIfExists in an Allow Statement

<table><thead><tr><th>Policy Condition</th><th>Request Context</th><th>Result</th></tr></thead><tbody><tr><td><pre><code>"ArnLikeIfExists": {
  "aws:PrincipalArn": [
    "arn:aws:iam::*:role/*",
    "arn:aws:ec2:*:*:instance/i-?????"
  ]
}
</code></pre></td><td><code>aws:PrincipalArn: null</code></td><td><img src="https://iam.cloudcopilot.io/_astro/allow.BKwnWDMp_Z2m9B7U.svg" alt="Allowed"> AllowedAssuming no explicit Deny elsewhere</td></tr><tr><td><pre><code>"ArnLikeIfExists": {
  "aws:PrincipalArn": [
    "arn:aws:iam::*:role/*",
    "arn:aws:ec2:*:*:instance/i-?????"
  ]
}
</code></pre></td><td><code>aws:PrincipalArn:</code><br>   <code>arn:aws:iam::123456789012:role/AdminRole</code></td><td><img src="https://iam.cloudcopilot.io/_astro/allow.BKwnWDMp_Z2m9B7U.svg" alt="Allowed"> AllowedAssuming no explicit Deny elsewhere</td></tr><tr><td><pre><code>"ArnLikeIfExists": {
  "aws:PrincipalArn": [
    "arn:aws:iam::*:role/*",
    "arn:aws:ec2:*:*:instance/i-?????"
  ]
}
</code></pre></td><td><code>aws:PrincipalArn:</code><br>   <code>arn:aws:iam::123456789012:user/User</code></td><td><img src="https://iam.cloudcopilot.io/_astro/unknown.4jslFilM_ZFyvUV.svg" alt="Not Allowed"> Not AllowedStatement does not apply</td></tr></tbody></table>

<br>
