有时候，
man ls发现没有帮助文档，可以快递打开浏览器检索 "man ls" 。
# yum list | grep man | grep pages
gl-manpages.noarch 1.1-7.20130122.el7 @base
libguestfs-man-pages-ja.noarch 1:1.40.2-10.el7 base
libguestfs-man-pages-uk.noarch 1:1.40.2-10.el7 base
man-pages.noarch 3.53-5.el7 base
man-pages-cs.noarch 0.18.20090209-17.el7 base
man-pages-de.noarch 1.8-4.g7c4902d.el7 epel
man-pages-es.noarch 1.55-21.el7 base
man-pages-es-extra.noarch 1.55-21.el7 base
man-pages-fr.noarch 3.52-3.el7 base
man-pages-it.noarch 3.15-2.el7 base
man-pages-ja.noarch 20130615-6.el7 base
man-pages-ko.noarch 2:20050219-25.el7 base
man-pages-overrides.x86_64 7.9.0-1.el7 base
man-pages-pl.noarch 1:0.3-4.el7 base
man-pages-ru.noarch 3.41-3.20120901.el7 base
man-pages-zh-CN.noarch 1.5.2-4.el7 base
# man man
...
The table below shows the section numbers of the manual followed by the types of pages they contain.
1 Executable programs or shell commands
2 System calls (functions provided by the kernel)
3 Library calls (functions within program libraries)
4 Special files (usually found in /dev)
5 File formats and conventions eg /etc/passwd
6 Games
7 Miscellaneous (including macro packages and conventions), e.g. man(7), groff(7)
8 System administration commands (usually only for root)
9 Kernel routines [Non standard]
...
所以，man man 等于 man 1 man。
# rpm -qa | while read line ; do rpm -ql $line | grep -q man[1-9] && echo $line ; done
打印所有包含man文档的软件包，实际比想象的要包很多。