如何查找linux指令或者资料的说明
例子：查找printf的用法说明
- 先用 whatis printf 查看printf相关的信息（也可以用man -f printf，man --help中有介绍，两种方式一样）
ubuntu@VM-16-16-ubuntu:~$ whatis printf
printf (1) - format and print data
printf (3) - formatted output conversion
可以看到返回的内容：命令名称+命令在man手册中的章节+简述命令或函数的作用
小贴士：可以通过man man 查看到man手册9个章节的含义
1 Executable programs or shell commands
2 System calls (functions provided by the kernel)
3 Library calls (functions within program libraries) #一些常用函数库，大部分为C函数库
4 Special files (usually found in /dev)
5 File formats and conventions, e.g. /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]
-
要查找shell命令printf的详细说明，选择man手册的第一章 man 1 printf查看，当然也可以直接printf --help
要查找C语言printf库函数的用法，选择man手册的第三章 man 3 printf查看 -
如果要查找的指令或者函数名称包含printf，可以使用man -k printf（等价于apropos printf）
ubuntu@VM-16-16-ubuntu:~$ man -k printf
asprintf (3) - print to allocated string
dprintf (3) - formatted output conversion
fprintf (3) - formatted output conversion
fwprintf (3) - formatted wide-character output conversion
printf (1) - format and print data
printf (3) - formatted output conversion
snprintf (3) - formatted output conversion
sprintf (3) - formatted output conversion
swprintf (3) - formatted wide-character output conversion
vasprintf (3) - print to allocated string
vdprintf (3) - formatted output conversion
vfprintf (3) - formatted output conversion
vfwprintf (3) - formatted wide-character output conversion
vprintf (3) - formatted output conversion
vsnprintf (3) - formatted output conversion
vsprintf (3) - formatted output conversion
vswprintf (3) - formatted wide-character output conversion
vwprintf (3) - formatted wide-character output conversion
wprintf (3) - formatted wide-character output conversion
XtAsprintf (3) - memory management functions
参考资料
4.3 Linux系統的線上求助man page與info page
Linux中man手册的使用 ——以CentOS6.8为例