4. C++
sudo apt-get install libstdc++6-4.5-doc   //通过补齐查找具体的文件
//sudo apt-get install libstdc++6-4.3-doc //C++ API

1.添加库函数手册
ubuntu默认是没有安装c语言的库函数man手册的，所以你在man perror 和sendto之类的函数时会显示没有相关文档的问题，这个问题让我郁闷了我好久。解决方法：
sudo apt-get install manpages-dev
2.让man显示中文
ubuntu源里面已经包含了中文的man包，所以不用从其他地方down了，直接
sudo apt-get install manpages-zh
但是这样man默认显示的还不是中文，还需要以下两步
a.把中文man包转换成utf8格式的
新建一个脚本文件
gedit t.sh
把下面内容添加进去
#!/bin/bashcd /usr/share/man/zh_CN/for k in *docd $kfor i in *.gzdo j=`echo ${i%.gz}` gunzip $i iconv -f gb18030 -t utf8 $j >tmp mv tmp $j gzip $jdonecd ..done

           #!/bin/bashcd /usr/share/man/zh_CN/for k in *docd $kfor i in *.gzdoj=`echo ${i%\.gz}`gunzip $iiconv -f gb18030 -t utf8 $j >tmpmv tmp $jgzip $jdonecd ..done#我用上面装完再试着乱码显示。卸载重装 只装上面整个一句话成功。

然后
sudo chmod a+rwx t.sh
sudo ./t.sh
b.修改man默认的语言
sudo gedit /etc/manpath.config 把里面的所有的 /usr/share/man 改成 /usr/share/man/zh_CN
保存后退出，然后你再试一下man ls
3.让没有中文帮助的显示英文
做完上面第二部还不够，这时你再man 一下一些c语言函数（不要用printf，socket之类比较有名的函数，这些已经有中文帮助了）的时候就会发现竟然没有帮助，而刚才明明在第一步已经安装了啊。这是因为你上面 把/usr/share/man 改成 /usr/share/man/zh_CN的操作使man只在中文帮助中搜索，如果没有就直接放弃，因此还需要以下操作，才能让man在没有中文帮助的时候自动显示英文的帮助，如果英文的也没有，哪就真的没有了。
sudo gedit /etc/manpath.config
然后搜索你刚才改过的地方，然后在其后面添加同样的一行，只是后面的目录还用原来的/usr/share/man(所有的)，比如在修改后的
MANPATH_MAP /bin          /usr/share/man/zh_CN
再添加一行
MANPATH_MAP /bin          /usr/share/man

# manpath.config
#
# This file is used by the man-db package to configure the man and cat paths.
# It is also used to provide a manpath for those without one by examining
# their PATH environment variable. For details see the manpath(5) man page.
#
# Lines beginning with `#' are comments and are ignored. Any combination of
# tabs or spaces may be used as `whitespace' separators.
#
# There are three mappings allowed in this file:
# --------------------------------------------------------
# MANDATORY_MANPATH         manpath_element
# MANPATH_MAP       path_element    manpath_element
# MANDB_MAP     global_manpath  [relative_catpath]
#---------------------------------------------------------
# every automatically generated MANPATH includes these fields
#
#MANDATORY_MANPATH          /usr/src/pvm3/man
#
MANDATORY_MANPATH           /usr/man
MANDATORY_MANPATH           /usr/share/man/zh_CN
MANDATORY_MANPATH           /usr/local/share/man#MANDATORY_MANPATH          /usr/share/man
#---------------------------------------------------------
# set up PATH to MANPATH mapping
# ie. what man tree holds man pages for what binary directory.
#
#       *PATH*        -> *MANPATH*
#MANPATH_MAP    /bin            /usr/share/man/zh_CN
MANPATH_MAP /usr/bin        /usr/share/man/zh_CN
MANPATH_MAP /sbin           /usr/share/man/zh_CN
MANPATH_MAP /usr/sbin       /usr/share/man/zh_CN
MANPATH_MAP /usr/local/bin      /usr/local/man
MANPATH_MAP /usr/local/bin      /usr/local/share/man
MANPATH_MAP /usr/local/sbin     /usr/local/man
MANPATH_MAP /usr/local/sbin     /usr/local/share/man
MANPATH_MAP /usr/X11R6/bin      /usr/X11R6/man
MANPATH_MAP /usr/bin/X11        /usr/X11R6/man
MANPATH_MAP /usr/games      /usr/share/man/zh_CN
MANPATH_MAP /opt/bin        /opt/man
MANPATH_MAP /opt/sbin       /opt/man#MANPATH_MAP    /bin                 /usr/share/man  #让man在没有中文帮助的时候自动显示英文的帮助
#MANPATH_MAP    /usr/bin        /usr/share/man
#MANPATH_MAP    /sbin           /usr/share/man
#MANPATH_MAP    /usr/sbin       /usr/share/man
#MANPATH_MAP    /usr/games      /usr/share/man
#---------------------------------------------------------
# For a manpath element to be treated as a system manpath (as most of those
# above should normally be), it must be mentioned below. Each line may have
# an optional extra string indicating the catpath associated with the
# manpath. If no catpath string is used, the catpath will default to the
# given manpath.
#
# You *must* provide all system manpaths, including manpaths for alternate
# operating systems, locale specific manpaths, and combinations of both, if
# they exist, otherwise the permissions of the user running man/mandb will
# be used to manipulate the manual pages. Also, mandb will not initialise
# the database cache for any manpaths not mentioned below unless explicitly
# requested to do so.
#
# In a per-user configuration file, this directive only controls the
# location of catpaths and the creation of database caches; it has no effect
# on privileges.
#
# Any manpaths that are subdirectories of other manpaths must be mentioned
# *before* the containing manpath. E.g. /usr/man/preformat must be listed
# before /usr/man.
#
#       *MANPATH*     -> *CATPATH*
#
MANDB_MAP   /usr/man        /var/cache/man/fsstnd
MANDB_MAP   /usr/share/man/zh_CN        /var/cache/man
MANDB_MAP   /usr/local/man      /var/cache/man/oldlocal
MANDB_MAP   /usr/local/share/man    /var/cache/man/local
MANDB_MAP   /usr/X11R6/man      /var/cache/man/X11R6
MANDB_MAP   /opt/man        /var/cache/man/opt
#
#---------------------------------------------------------
# Program definitions.  These are commented out by default as the value
# of the definition is already the default.  To change: uncomment a
# definition and modify it.
#
#DEFINE     pager   pager -s
#DEFINE     cat cat
#DEFINE     tr  tr '\255\267\264\327' '\055\157\047\170'
#DEFINE     grep    grep
#DEFINE     troff   groff -mandoc
#DEFINE     nroff   nroff -mandoc
#DEFINE     eqn     eqn
#DEFINE     neqn    neqn
#DEFINE     tbl     tbl
#DEFINE     col     col
#DEFINE     vgrind  vgrind
#DEFINE     refer   refer
#DEFINE     grap    grap
#DEFINE     pic     pic -S
#
#DEFINE     compressor  gzip -c7
#---------------------------------------------------------
# Misc definitions: same as program definitions above.
#
#DEFINE     whatis_grep_flags       -i
#DEFINE     apropos_grep_flags      -iEw
#DEFINE     apropos_regex_grep_flags    -iE
#---------------------------------------------------------
# Section names. Manual sections will be searched in the order listed here;
# the default is 1, n, l, 8, 3, 0, 2, 5, 4, 9, 6, 7. Multiple SECTION
# directives may be given for clarity, and will be concatenated together in
# the expected way.
# If a particular extension is not in this list (say, 1mh), it will be
# displayed with the rest of the section it belongs to. The effect of this
# is that you only need to explicitly list extensions if you want to force a
# particular order. Sections with extensions should usually be adjacent to
# their main section (e.g. "1 1mh 8 ...").
#
SECTION     1 n l 8 3 2 3posix 3pm 3perl 5 4 9 6 7
#
#---------------------------------------------------------
# Range of terminal widths permitted when displaying cat pages. If the
# terminal falls outside this range, cat pages will not be created (if
# missing) or displayed.
#
#MINCATWIDTH    80
#MAXCATWIDTH    80
#
# If CATWIDTH is set to a non-zero number, cat pages will always be
# formatted for a terminal of the given width, regardless of the width of
# the terminal actually being used. This should generally be within the
# range set by MINCATWIDTH and MAXCATWIDTH.
#
#CATWIDTH   0
#
#---------------------------------------------------------
# Flags.
# NOCACHE keeps man from creating cat pages.
#NOCACHE

参考：http://blog.csdn.net/linking530/article/details/7284482
http://blog.csdn.net/chang198932/article/details/18728703
http://blog.163.com/fanning_7213/blog/static/2496505201102610539141/