问题

报错如下

convert: not authorized `-' @ 

解决

修改/etc/ImageMagick/policy.xml为如下

<policymap>
  <!-- <policy domain="system" name="precision" value="6"/> -->
  <!-- <policy domain="resource" name="temporary-path" value="/tmp"/> -->
  <!-- <policy domain="resource" name="memory" value="2GiB"/> -->
  <!-- <policy domain="resource" name="map" value="4GiB"/> -->
  <!-- <policy domain="resource" name="area" value="1GB"/> -->
  <!-- <policy domain="resource" name="disk" value="16EB"/> -->
  <!-- <policy domain="resource" name="file" value="768"/> -->
  <!-- <policy domain="resource" name="thread" value="4"/> -->
  <!-- <policy domain="resource" name="throttle" value="0"/> -->
  <!-- <policy domain="resource" name="time" value="3600"/> -->
  <policy domain="coder" rights="none" pattern="EPHEMERAL" />
  <policy domain="coder" rights="read" pattern="HTTPS" />
  <policy domain="coder" rights="none" pattern="HTTP" />
  <policy domain="coder" rights="none" pattern="URL" />
  <policy domain="coder" rights="none" pattern="FTP" />
  <policy domain="coder" rights="none" pattern="MVG" />
  <policy domain="coder" rights="none" pattern="MSL" />
  <policy domain="coder" rights="none" pattern="TEXT" />
  <!--policy domain="coder" rights="read | write" pattern="LABEL" /-->
  <policy domain="path" rights="none" pattern="@*" />
  <policy domain="coder" rights="read | write" pattern="JPEG" />
  <policy domain="coder" rights="read | write" pattern="PNG" />
</policymap>

可以参考