# Linux tr命令 Linux tr 命令用于转换或删除文件中的字符。 tr 指令从标准输入设备读取数据，经过字符串转译后，将结果输出到标准输出设备。 ### 语法 ``` tr [-cdst][--help][--version][第一字符集][第二字符集] tr [OPTION]…SET1[SET2] ``` **参数说明：** * -c, --complement：反选设定字符。也就是符合 SET1 的部份不做处理，不符合的剩余部份才进行转换 * -d, --delete：删除指令字符 * -s, --squeeze-repeats：缩减连续重复的字符成指定的单个字符 * -t, --truncate-set1：削减 SET1 指定范围，使之与 SET2 设定长度相等 * --help：显示程序用法信息 * --version：显示程序本身的版本信息 字符集合的范围： * \NNN 八进制值的字符 NNN (1 to 3 为八进制值的字符) * \\ 反斜杠 * \a Ctrl-G 铃声 * \b Ctrl-H 退格符 * \f Ctrl-L 走行换页 * \n Ctrl-J 新行 * \r Ctrl-M 回车 * \t Ctrl-I tab键 * \v Ctrl-X 水平制表符 * CHAR1-CHAR2 ：字符范围从 CHAR1 到 CHAR2 的指定，范围的指定以 ASCII 码的次序为基础，只能由小到大，不能由大到小。 * [CHAR*] ：这是 SET2 专用的设定，功能是重复指定的字符到与 SET1 相同长度为止 * [CHAR*REPEAT] ：这也是 SET2 专用的设定，功能是重复指定的字符到设定的 REPEAT 次数为止(REPEAT 的数字采 8 进位制计算，以 0 为开始) * [:alnum:] ：所有字母字符与数字 * [:alpha:] ：所有字母字符 * [:blank:] ：所有水平空格 * [:cntrl:] ：所有控制字符 * [:digit:] ：所有数字 * [:graph:] ：所有可打印的字符(不包含空格符) * [:lower:] ：所有小写字母 * [:print:] ：所有可打印的字符(包含空格符) * [:punct:] ：所有标点字符 * [:space:] ：所有水平与垂直空格符 * [:upper:] ：所有大写字母 * [:xdigit:] ：所有 16 进位制的数字 * [=CHAR=] ：所有符合指定的字符(等号里的 CHAR，代表你可自订的字符) ### 实例 将文件testfile中的小写字母全部转换成大写字母，此时，可使用如下命令： ``` cat testfile |tr a-z A-Z ``` testfile文件中的内容如下： ``` $ cat testfile #testfile原来的内容 Linux networks are becoming more and more common, but scurity is often an overlooked issue. Unfortunately, in today’s environment all networks are potential hacker targets, fro0m tp-secret military research networks to small home LANs. Linux Network Securty focuses on securing Linux in a networked environment, where the security of the entire network needs to be considered rather than just isolated machines. It uses a mix of theory and practicl techniques to teach administrators how to install and use security applications, as well as how the applcations work and why they are necesary. ``` 使用 tr 命令大小写转换后，得到如下输出结果： ``` $ cat testfile | tr a-z A-Z #转换后的输出 LINUX NETWORKS ARE BECOMING MORE AND MORE COMMON, BUT SCURITY IS OFTEN AN OVERLOOKED ISSUE. UNFORTUNATELY, IN TODAY’S ENVIRONMENT ALL NETWORKS ARE POTENTIAL HACKER TARGETS, FROM TP-SECRET MILITARY RESEARCH NETWORKS TO SMALL HOME LANS. LINUX NETWORK SECURTY FOCUSES ON SECURING LINUX IN A NETWORKED ENVIRONMENT, WHERE THE SECURITY OF THE ENTIRE NETWORK NEEDS TO BE CONSIDERED RATHER THAN JUST ISOLATED MACHINES. IT USES A MIX OF THEORY AND PRACTICL TECHNIQUES TO TEACH ADMINISTRATORS HOW TO INSTALL AND USE SECURITY APPLICATIONS, AS WELL AS HOW THE APPLCATIONS WORK AND WHY THEY ARE NECESARY. ``` 大小写转换，也可以通过[:lower][:upper]参数来实现。例如使用如下命令： ``` cat testfile |tr [:lower:] [:upper:] ``` 输出结果如下： ``` $ cat testfile | tr [:lower:] [:upper:] #转换后的输出 LINUX NETWORKS ARE BECOMING MORE AND MORE COMMON, BUT SCURITY IS OFTEN AN OVERLOOKED ISSUE. UNFORTUNATELY, IN TODAY’S ENVIRONMENT ALL NETWORKS ARE POTENTIAL HACKER TARGETS, FROM TP-SECRET MILITARY RESEARCH NETWORKS TO SMALL HOME LANS. LINUX NETWORK SECURTY FOCUSES ON SECURING LINUX IN A NETWORKED ENVIRONMENT, WHERE THE SECURITY OF THE ENTIRE NETWORK NEEDS TO BE CONSIDERED RATHER THAN JUST ISOLATED MACHINES. IT USES A MIX OF THEORY AND PRACTICL TECHNIQUES TO TEACH ADMINISTRATORS HOW TO INSTALL AND USE SECURITY APPLICATIONS, AS WELL AS HOW THE APPLCATIONS WORK AND WHY THEY ARE NECESARY. ```