dos2unix 主要解决特殊字符的问题
简单的用法案例：
$dos2unix xxx.txt
help信息：
$ dos2unix -h
dos2unix Copyright (c) 1994-1995 Benjamin Lin
Copyright (c) 1998 Bernd Johannes Wuebben (Version 3.0)
Copyright (c) 1998 Christian Wurll (Version 3.1)
Usage: dos2unix [-hkqV] [-c convmode] [-o file ...] [-n infile outfile ...]
-h --help give this help
-k --keepdate keep output file date
-q --quiet quiet mode, suppress all warnings
always on in stdin->stdout mode
-V --version display version number
-c --convmode conversion mode
convmode ASCII, 7bit, ISO, Mac, default to ASCII
-l --newline add additional newline in all but Mac convmode
-o --oldfile write to old file
file ... files to convert in old file mode
-n --newfile write to new file
infile original file in new file mode
outfile output file in new file mode