用ImageMagic convert命令将*.pdf文件转换为*.pdf文件。收到以下错误：
convert-im6.q16: not authorized `xxx.pdf' @ error/constitute.c/ReadImage/412.
编辑文件/etc/ImageMagick-6/policy.xml
policy domain="coder" rights="none" pattern="PDF"
改为
policy domain="coder" rights="read|write" pattern="PDF"
同样道理，如果遇到以下报错：
mogrify-im6.q16: attempt to perform an operation not allowed by the security policy `@t.txt' @ error/property.c/InterpretImageProperties/3706
也是编辑/etc/ImageMagick-6/policy.xml 这个神奇的文件：
<policy domain="delegate" rights="none" pattern="URL" />
<policy domain="delegate" rights="none" pattern="HTTPS" />
<policy domain="delegate" rights="none" pattern="HTTP" />
<!-- in order to avoid to get image with password text -->
<policy domain="path" rights="read|write" pattern="@*"/>
<!-- disable ghostscript format types -->
<policy domain="coder" rights="none" pattern="PS" />
<policy domain="coder" rights="none" pattern="PS2" />
<policy domain="coder" rights="none" pattern="PS3" />
<policy domain="coder" rights="none" pattern="EPS" />
<policy domain="coder" rights="none" pattern="PDF" />
<policy domain="coder" rights="none" pattern="XPS" />例如这里是@t.txt 报错，对应的就是修改pattern="@*"这一行，把none改为read|write 。
同样，如果其他例如pdf的报错，Xps的报错，把none改为“read|write”就ok了。
另外，可能会存在多个xml配置文件的问题，怎么样把它全部改掉生效？如何确定使用的是哪个配置文件？
第一种方案：
sed -i 's/rights="none" pattern="PDF"/rights="read|write" pattern="PDF"/g' /etc/ImageMagick-6/policy.xml第二种方案：自动获取 policy.xml 文件的位置并对它们全部执行搜索/替换
for file in `convert -list policy | grep "Path:" | grep -v built | sed 's/Path: \(.*\)/\1/g'`; do sed -i 's/domain="coder" rights="none" pattern="PDF"/domain="coder" rights="read|write" pattern="PDF"/g' $file; done参考：https://askubuntu.com/questions/1081895/trouble-with-batch-conversion-of-png-to-pdf-using-convert
完整可用的例子：
# cat /etc/ImageMagick-6/policy.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE policymap [
<!ELEMENT policymap (policy)*>
<!ATTLIST policymap xmlns CDATA #FIXED ''>
<!ELEMENT policy EMPTY>
<!ATTLIST policy xmlns CDATA #FIXED '' domain NMTOKEN #REQUIRED
name NMTOKEN #IMPLIED pattern CDATA #IMPLIED rights NMTOKEN #IMPLIED
stealth NMTOKEN #IMPLIED value CDATA #IMPLIED>
]>
<!--
Configure ImageMagick policies.
Domains include system, delegate, coder, filter, path, or resource.
Rights include none, read, write, execute and all. Use | to combine them,
for example: "read | write" to permit read from, or write to, a path.
Use a glob expression as a pattern.
Suppose we do not want users to process MPEG video images:
<policy domain="delegate" rights="none" pattern="mpeg:decode" />
Here we do not want users reading images from HTTP:
<policy domain="coder" rights="none" pattern="HTTP" />
The /repository file system is restricted to read only. We use a glob
expression to match all paths that start with /repository:
<policy domain="path" rights="read" pattern="/repository/*" />
Lets prevent users from executing any image filters:
<policy domain="filter" rights="none" pattern="*" />
Any large image is cached to disk rather than memory:
<policy domain="resource" name="area" value="1GP"/>
Use the default system font unless overwridden by the application:
<policy domain="system" name="font" value="/usr/share/fonts/favorite.ttf"/>
Define arguments for the memory, map, area, width, height and disk resources
with SI prefixes (.e.g 100MB). In addition, resource policies are maximums
for each instance of ImageMagick (e.g. policy memory limit 1GB, -limit 2GB
exceeds policy maximum so memory limit is 1GB).
Rules are processed in order. Here we want to restrict ImageMagick to only
read or write a small subset of proven web-safe image types:
<policy domain="delegate" rights="none" pattern="*" />
<policy domain="filter" rights="none" pattern="*" />
<policy domain="coder" rights="none" pattern="*" />
<policy domain="coder" rights="read|write" pattern="{GIF,JPEG,PNG,WEBP}" />
-->
<policymap>
<!-- <policy domain="resource" name="temporary-path" value="/tmp"/> -->
<policy domain="resource" name="memory" value="256MiB"/>
<policy domain="resource" name="map" value="512MiB"/>
<policy domain="resource" name="width" value="16KP"/>
<policy domain="resource" name="height" value="16KP"/>
<!-- <policy domain="resource" name="list-length" value="128"/> -->
<policy domain="resource" name="area" value="128MP"/>
<policy domain="resource" name="disk" value="1GiB"/>
<!-- <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="MVG" /> -->
<!-- <policy domain="module" rights="none" pattern="{PS,PDF,XPS}" /> -->
<!-- <policy domain="path" rights="none" pattern="@*" /> -->
<!-- <policy domain="cache" name="memory-map" value="anonymous"/> -->
<!-- <policy domain="cache" name="synchronize" value="True"/> -->
<!-- <policy domain="cache" name="shared-secret" value="passphrase" stealth="true"/>
<!-- <policy domain="system" name="max-memory-request" value="256MiB"/> -->
<!-- <policy domain="system" name="shred" value="2"/> -->
<!-- <policy domain="system" name="precision" value="6"/> -->
<!-- <policy domain="system" name="font" value="/path/to/font.ttf"/> -->
<!-- <policy domain="system" name="pixel-cache-memory" value="anonymous"/> -->
<!-- <policy domain="system" name="shred" value="2"/> -->
<!-- <policy domain="system" name="precision" value="6"/> -->
<!-- not needed due to the need to use explicitly by mvg: -->
<!-- <policy domain="delegate" rights="none" pattern="MVG" /> -->
<!-- use curl -->
<policy domain="delegate" rights="none" pattern="URL" />
<policy domain="delegate" rights="none" pattern="HTTPS" />
<policy domain="delegate" rights="none" pattern="HTTP" />
<!-- in order to avoid to get image with password text -->
<policy domain="path" rights="read|write" pattern="@*"/>
<!-- disable ghostscript format types -->
<policy domain="coder" rights="none" pattern="PS" />
<policy domain="coder" rights="none" pattern="PS2" />
<policy domain="coder" rights="none" pattern="PS3" />
<policy domain="coder" rights="none" pattern="EPS" />
<policy domain="coder" rights="none" pattern="PDF" />
<policy domain="coder" rights="none" pattern="XPS" />
</policymap>