====== apropos: Linux中除man以外很强大的帮助命令 ======

前Linux中帮助一直使用man，但前提是知道这个命令怎么写。

如果遇到想完成某个功能，但具体命令忘了的时候怎么办能。

新发现从来也没用过的apropos, 直接输入apropos [keyword], 即可查看与keyword相关功能的命令。

该命令实际完成的是搜索其它命令的描述信息，将相关命令罗列出来，不一定出现的命令就是想要的，但可以从中帮助回忆到有用的命令。

===== apropos 使用方法 =====
man apropos 自己看。

===== apropos 例子 =====
用apropos查找和sort相关的命令：

apropos sort

<code>
alphasort [scandir]  (3)  - scan a directory for matching entries
bsearch              (3)  - binary search of a sorted array
bsearch              (3p)  - binary search a sorted table
bunzip2              (1)  - a block-sorting file compressor, v1.0.2
bunzip2 [bzcat]      (1)  - a block-sorting file compressor, v1.0.2
bunzip2 [bzip2]      (1)  - a block-sorting file compressor, v1.0.2
bunzip2 [bzip2recover] (1)  - a block-sorting file compressor, v1.0.2
bzip2                (1)  - a block-sorting file compressor, v1.0.2
bzip2 [bunzip2]      (1)  - a block-sorting file compressor, v1.0.2
bzip2 [bzcat]        (1)  - a block-sorting file compressor, v1.0.2
bzip2 [bzip2recover] (1)  - a block-sorting file compressor, v1.0.2
comm                 (1)  - compare two sorted files line by line
iterator_info_s [netsnmp_iterator_info_s] (3)  - Holds iterator information containing functions which should be called by the iterator_handler to loop over your data set and sort it in a SNMP specific manner
ldap_sort_entries    (3)  - LDAP sorting routines
ldap_sort_entries [ldap_sort] (3)  - LDAP sorting routines
ldap_sort_entries [ldap_sort_strcasecmp] (3)  - LDAP sorting routines
ldap_sort_entries [ldap_sort_values] (3)  - LDAP sorting routines
ldap_sort_strcasecmp (3)  - LDAP sorting routines
ldap_sort_strcasecmp [ldap_sort] (3)  - LDAP sorting routines
ldap_sort_strcasecmp [ldap_sort_entries] (3)  - LDAP sorting routines
ldap_sort_strcasecmp [ldap_sort_values] (3)  - LDAP sorting routines
ldap_sort_values     (3)  - LDAP sorting routines
ldap_sort_values [ldap_sort] (3)  - LDAP sorting routines
ldap_sort_values [ldap_sort_entries] (3)  - LDAP sorting routines
ldap_sort_values [ldap_sort_strcasecmp] (3)  - LDAP sorting routines
lsort                (n)  - Sort the elements of a list
qsort                (3)  - sorts an array
qsort                (3p)  - sort a table of data
sort                 (1)  - sort lines of text files
sort                 (1p)  - sort, merge, or sequence check text files
sort                 (3pm)  - perl pragma to control sort() behaviour
texindex             (1)  - sort Texinfo index files
tsort                (1)  - perform topological sort
tsort                (1p)  - topological sort
uniq                 (1)  - remove duplicate lines from a sorted file
versionsort [scandir] (3)  - scan a directory for matching entries
</code>