用来测试文件类型

$file [] filename

-b列出辨识结果时，但不显示文件名称

-L如果文件是符号链接，那么直接解读其指向的文件

-z：如果文件是压缩文件，尝试去解读压缩文件的内容

$file bookmarks.html bookmarks.html: exported SGML document, UTF-8 Unicode text, with very long lines$file exec.shexec.sh: Bourne-Again shell script, ASCII text executable$file rxvt_1%3a2.6.4-14_i386.deb rxvt_1%3a2.6.4-14_i386.deb: Debian binary package (format 2.0)$file test_wc.c test_wc.c: ASCII text$file -b cnblogs/ exec.sh directoryBourne-Again shell script, ASCII text executable