如果您想消除警告，因为您位于容器中，并且不太可能像链接的问题中所指出的那样，出现多个用户将有文件权限问题的问题，那么您可以简单地定义一个环境变量并使其指向/tmp目录。

下面是一个使用 pandoc 和 wkhtmltopdf 的示例，通常会出现此错误：

FROM ubuntu:focal
ARG DEBIAN_FRONTEND=noninteractive 
RUN apt-get update -qq \
    && apt-get install --yes pandoc wkhtmltopdf \
    && echo "# Hello world!" > demo.md
ENV XDG_RUNTIME_DIR=/tmp
## ^-- This is the interesting line for you
CMD [ \
    "pandoc", \
    "demo.md", \
    "--output", "demo.pdf", \
    "--pdf-engine", "wkhtmltopdf", \
    "--metadata", "pagetitle='Demo'" \
]

如果没有 ENV ，它将产生：

QStandardPaths: XDG_RUNTIME_DIR not set, defaulting to '/tmp/runtime-root'
Loading page (1/2)
Printing pages (2/2)                                               
Done  

这样，它就会是：

Loading page (1/2)
Printing pages (2/2)                                               
Done  

如果您想按建议使用一个文件夹 /run/user/<UID> ，那么您必须首先创建该文件夹并分配正确的权限。

对于以 root 形式运行的容器

FROM ubuntu:focal
ARG DEBIAN_FRONTEND=noninteractive 
RUN apt-get update -qq \
    && apt-get install --yes pandoc wkhtmltopdf \
    && echo "# Hello world!" > demo.md \ 
    && mkdir -p -m 0700 /run/user/0
##       ^-- now you also have this last line
ENV XDG_RUNTIME_DIR=/run/user/0
## ^-- And still that one
CMD [ \
    "pandoc", \
    "demo.md", \
    "--output", "demo.pdf", \
    "--pdf-engine", "wkhtmltopdf", \
    "--metadata", "pagetitle='Demo'" \
]

对于以其他用户身份运行的容器：

FROM ubuntu:focal
ARG DEBIAN_FRONTEND=noninteractive 
ARG UID=1000
WORKDIR /tmp
RUN apt-get update -qq \
    && apt-get install --yes pandoc wkhtmltopdf \
    && echo "# Hello world!" > demo.md \ 
    && chmod 766 demo.md \
    && useradd --uid "${UID}" user \
    && mkdir -p -m 0700 /run/user/"${UID}" \
    && chown user:user /run/user/"${UID}"
##       ^-- and, now, you have those three last lines
USER user
ENV XDG_RUNTIME_DIR=/run/user/"${UID}"
## ^-- And still that one, plus the user definition, of course
CMD [ \