in container,I can't use man in ubuntu image ,by search i find this link to slove the problem
cp /etc/dpkg/dpkg.cfg.d/excludes /etc/dpkg/dpkg.cfg.d/excludes.bak apt update && apt-get install -y man manpages-posix
how to use man in centos image? I find this link
remove "tsflags=nodocs" from "/etc/yum.conf"
yum install -y man man-pages
this link explanation it:
Package documentation
By default, the CentOS containers are built using yum's
nodocsoption, which helps reduce the size of the image. If you install a package and discover files missing, please comment out the linetsflags=nodocsin/etc/yum.confand reinstall your package.