tr用法

参考：

http://man.linuxde.net/tr

shell脚本学习指南

语法

　　tr [options] source-char-list replace-char-list

用途

　　转换字符。例如，将大写字符转换成小写。选项可让你指定要删除的字符，以及将一串重复出现的字符浓缩成一个。

　　Translate, squeeze, and/or delete characters from standard input, writing to standard output.

常用选项

　　-c或--complement：取代所有不属于第一字符集的字符；use the complement of source-char-list

　　-d或--delete：删除所有属于第一字符集的字符；delete characters in source-char-list, do not translate

　　-s或--squeeze-repeats：把连续重复的字符以单独一个字符表示；replace each input sequence of a repeated character that is listed in source-char-list with a single occurrence of that character.

　　-t或--truncate-set1：先删除第一字符集较第二字符集多出的字符。

支持的字符集

[:alnum:]　　all letters and digits

       [:alpha:]　　all letters

       [:blank:]　　all horizontal whitespace

       [:cntrl:]　　all control characters

       [:digit:]　　all digits

       [:graph:]　　all printable characters, not including space

[:lower:]　　all lower case letters

       [:print:]　　all printable characters, including space

       [:punct:]　　all punctuation characters

       [:space:]　　all horizontal or vertical whitespace

       [:upper:]　　 all upper case letters

       [:xdigit:]　　all hexadecimal digits

       [=CHAR=]　　all characters which are equivalent to CHAR

举例

　　将小写字符转换为大写字母

tr [:lower:] [:upper:]