命令简介：

该命令用来识别文件类型，也可用来辨别一些文件的编码格式。它是通过查看文件的头部信息来获取文件类型，而不是像Windows通过扩展名来确定文件类型的。

执行权限 ：All User

指令所在路径：/usr/bin/file

命令语法：

代码如下:

file [ -bchikLnNprsvz ] [ -f namefile ] [ -F separator ] [ -m magicfiles ] file ...

命令参数：

下表列出了部分常用的参数。

使用示例：

代码如下:

[root@DB-Server ~]# file --help

Usage: file [OPTION]... [FILE]...

Determine file type of FILEs.

-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

-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

-k, --keep-going don't stop at the first match

-L, --dereference causes symlinks to be followed -n, --no-buffer do not buffer output

-N, --no-pad do not pad output

-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

--help display this help and exit

--version output version information and exit

当然你也可以使用 man file 获取更加详细的帮助文档信息。

2：不输出文件名称，只显示文件格式以及编码

通过下面两个命令对时，就可以清晰的了解参数-b的作用。

代码如下:

[root@DB-Server ~]# file Temp.txt Temp.txt: UTF-8 Unicode text, with very long lines, with CRLF line terminators[root@DB-Server ~]# file -b Temp.txtUTF-8 Unicode text, with very long lines, with CRLF line terminators

3: 输出mime类型的字符串

代码如下:

[root@DB-Server ~]# file -i Temp.txt Temp.txt: text/plain; charset=utf-8

4: 查看文件中的文件名的文件类型

这个参数非常适合shell脚本去查找、判别某种文件类型的数据。

你可以像下面这样使用 file 命令确定文件的类型。下面的截图显示了用 file 命令确定不同文件类型的例子。

代码如下:

tecmint@tecmint ~/Linux-Tricks $ dir

BACKUP master.zip

crossroads-stable.tar.gz num.txt

EDWARD-MAYA-2011-2012-NEW-REMIX.mp3 reggea.xspf

Linux-Security-Optimization-Book.gif tmp-link

tecmint@tecmint ~/Linux-Tricks $ file BACKUP/

BACKUP/: directory

tecmint@tecmint ~/Linux-Tricks $ file master.zip

master.zip: Zip archive data, at least v1.0 to extract

tecmint@tecmint ~/Linux-Tricks $ file crossroads-stable.tar.gz

crossroads-stable.tar.gz: gzip compressed data, from Unix, last modified: Tue Apr 5 15:15:20 2011

tecmint@tecmint ~/Linux-Tricks $ file Linux-Security-Optimization-Book.gif

Linux-Security-Optimization-Book.gif: GIF image data, version 89a, 200 x 259

tecmint@tecmint ~/Linux-Tricks $ file EDWARD-MAYA-2011-2012-NEW-REMIX.mp3

EDWARD-MAYA-2011-2012-NEW-REMIX.mp3: Audio file with ID3 version 2.3.0, contains: MPEG ADTS, layer III, v1, 192 kbps, 44.1 kHz, JntStereo

tecmint@tecmint ~/Linux-Tricks $ file /dev/sda1

/dev/sda1: block special

tecmint@tecmint ~/Linux-Tricks $ file /dev/tty1

/dev/tty1: character special

5：尝试去解读压缩文件的内容

代码如下:

[root@DB-Server ~]# file -z Temp.txt.gz Temp.txt.gz: UTF-8 Unicode text, with very long lines, with CRLF line terminators (gzip compressed data, was "Temp.txt", from Unix, last modified: Tue Jun 24 00:34:15 2014)[root@DB-Server ~]#

6： 查看软链接对应文件的文件类型

如下所示，创建一个软链接sfile，然后分别用file 和带参数的file -L查看

代码如下:

[root@DB-Server ~]# ln -s Temp.txt.gz sfile[root@DB-Server ~]# file sfile sfile: symbolic link to `Temp.txt.gz'[root@DB-Server ~]# file -L sfile sfile: gzip compressed data, was "Temp.txt", from Unix, last modified: Tue Jun 24 00:34:15 2014[root@DB-Server ~]#