file 官方解释：Determine type of FILEs. 判定文件的类型。 

小知识：在UNIX/Linux系统中，文件类型并不是由扩展名决定的（Windows是的）。 

开篇例子:

1. $file file.txt

输出：file.txt: ASCII English text

注：file.txt是我用file –help > file.txt生成的帮助文档 

查看—help

Usage: file [OPTION...] [FILE...]
Determine type of FILEs.

--help   display this help and exit

-v, --version   output version information and exit
-m, --magic-file  LIST  use LIST as a colon-separated list of magic
number files
-z, --uncompress   try to look inside compressed files
-b, --brief    do not prepend filenames to output lines
-c, --checking-printout   print the parsed form of the magic file, use in
conjunction with -m to debug a new magic file before installing it
-e, --exclude TEST   exclude TEST from the list of test to be performed for file. Valid tests are: ascii, apptype, compress, elf, soft, tar, tokens, troff
-f, --files-from FILE   read the filenames to be examined from FILE
-F, --separator STRING   use string as separator instead of `:'
-i, --mime  output MIME type strings (--mime-type and
--mime-encoding)
--apple  output the Apple CREATOR/TYPE
--mime-type  output the MIME type
--mime-encoding  output the MIME encoding
-k, --keep-going  don't stop at the first match
-l, --list  list magic strength
-L, --dereference  follow symlinks (default)
-h, --no-dereference  don't follow symlinks
-n, --no-buffer  do not buffer output
-N, --no-pad  do not pad output
-0, --print0  terminate filenames with ASCII NUL
-p, --preserve-date  preserve access times on files
-r, --raw  don't translate unprintable chars to \ooo
-s, --special-files  treat special (block/char devices) files as ordinary ones
-C, --compile  compile file specified by -m
-d, --debug  print debugging messages

 

解读： 

1. -z

查看压缩文件内的信息

2. -b, -e, -i, –r

-b 去掉输出行的前缀命名

-e 从测试列表到被执行文件排除测试。有效的测试包括：ascii, apptype, compress, elf, soft, tar,

-i 打印MIME

-R 不转译无法打印的字符为\ooo

3. magic file

以mgc为扩展名的文件，Microsoft office媒体目录文件

 

实战实例：

1. 

 
    
     
         
  1. $file -z file.zip 
    2.  
        
 
    
查看file.zip包中的文件信息
 
    
2. 
 
    
 
    
     
         
  1. $file –i file.txt 
    2.  
        
 
    
out:file.txt: text/plain; charset=us-ascii
 
    
打印MIME类型
 
    
 
 
    
 
    
     
         
  1. $file file.txt 
    2.  
        
 
    
out:file.txt: ASCII English text
 
    
3. magic file 
 
    
我翻译起来实在蹩脚。。 只能猜测查看$which file 看看，没有收获。最终通过$file得到
 
    
  
 
    
             
         
Usage: file  [-bchikLlNnprsvz0] [--apple] [--mime-encoding] [--mime-type] 
       [-e testname] [-F separator] [-f namefile] [-m magicfiles] file ... 
 file  -C [-m magicfiles] 
 file  [--help]
 		       
           
 
    
然后尝试file –C 得到magic.mgc文件。。。 不知有何用，惭愧
 
    
 有点尴尬的翻译了一下 见附件。