[Shell]tr命令详解

1. 用途@H_403_3@

tr，translate的简写，主要用于压缩重复字符，删除文件中的控制字符以及进行字符转换操作。@H_403_3@

2. 语法@H_403_3@

tr@H_403_3@[@H_403_3@OPTION@H_403_3@]...@H_403_3@SET1@H_403_3@SET2@H_403_3@]@H_403_3@

3. 参数@H_403_3@@H_403_3@

3.1 -s 压缩重复字符@H_403_3@

-s： squeeze-repeats，用SET1指定的字符来替换对应的重复字符（replace each input sequence of a repeated character that is@H_403_3@listed in SET1 wi@H_403_3@th a single occurrence of that character@H_403_3@）@H_403_3@

xiaosi@Qunar@H_403_3@:~/@H_403_3@test$ echo@H_403_3@"aaabbbaacccfddd"@H_403_3@@H_403_3@|@H_403_3@-@H_403_3@s@H_403_3@abcdf@H_403_3@] // abacfd@H_403_3@

可以使用这一特点，删除文件中的空白行，实质上跟上面一样，都是用SET1指定的字符来替换对应的重复字符

test$ cat b@H_403_3@.@H_403_3@txt@H_403_3@ 
     I like football@H_403_3@ 
      
      
     Football@H_403_3@is very fun@H_403_3@!@H_403_3@ 
      
     Hello@H_403_3@ 
     txt@H_403_3@[@H_403_3@"\n"@H_403_3@]@H_403_3@ 
     I like football@H_403_3@ 
     !@H_403_3@ 
     Hello@H_403_3@

3.2 -d 删除字符@H_403_3@

-d：delete，删除SET1中指定的所有字符，不转换（delete characters in SET1,do not translate）

"a12HJ13fdaADff"@H_403_3@d@H_403_3@"[a-z][A-Z]"@H_403_3@ 
     1213@H_403_3@ 
     "a1213fdasf"@H_403_3@d@H_403_3@adfs@H_403_3@]@H_403_3@ 
     1213@H_403_3@

3.3 字符替换@H_403_3@

-t：truncate，将SET1中字符用SET2对应位置的字符进行替换，一般缺省为-t@H_403_3@

t@H_403_3@afd@H_403_3@]@H_403_3@AFO@H_403_3@@H_403_3@// A1213FOAsF@H_403_3@

上述代码将a转换为A，f转换为F，d转换为O。

可以利用这一特点，实现大小字母的转换

"Hello World I Love You"@H_403_3@a@H_403_3@z@H_403_3@A@H_403_3@Z@H_403_3@]@H_403_3@ 
    HELLO WORLD I LOVE YOU@H_403_3@ 
    "HELLO WORLD I LOVE YOU"@H_403_3@]@H_403_3@ 
    hello world i love you@H_403_3@

也可以利用字符集合进行转换@H_403_3@

[:@H_403_3@lower@H_403_3@:]@H_403_3@upper@H_403_3@:]@H_403_3@

HELLO WORLD I LOVE YOU@H_403_3@

:]@H_403_3@

hello world i love you@H_403_3@

备注：@H_403_3@@H_403_3@

字符集合如下

\NNN@H_403_3@八进制值的字符@H_403_3@NNN@H_403_3@(@H_403_3@1@H_403_3@to@H_403_3@3@H_403_3@为八进制值的字符)@H_403_3@

\\@H_403_3@反斜杠@H_403_3@

\a@H_403_3@Ctrl@H_403_3@G@H_403_3@铃声@H_403_3@

\b@H_403_3@H@H_403_3@退格符@H_403_3@

\f@H_403_3@L@H_403_3@走行换页@H_403_3@

\n@H_403_3@J@H_403_3@新行@H_403_3@

\r@H_403_3@M@H_403_3@回车@H_403_3@

\t@H_403_3@I tab@H_403_3@键@H_403_3@

\v@H_403_3@X@H_403_3@水平制表符@H_403_3@

CHAR1@H_403_3@CHAR2@H_403_3@从@H_403_3@到@H_403_3@的所有字符按照@H_403_3@ASCII@H_403_3@字符的顺序@H_403_3@

CHAR@H_403_3@*]@H_403_3@in SET2@H_403_3@,@H_403_3@copies of CHAR until length of SET1@H_403_3@

*@H_403_3@REPEAT@H_403_3@REPEAT copies of CHAR@H_403_3@REPEAT octal@H_403_3@if@H_403_3@starting with@H_403_3@0@H_403_3@

alnum@H_403_3@所有的字母和数字@H_403_3@

alpha@H_403_3@所有字母@H_403_3@

blank@H_403_3@水平制表符，空白等@H_403_3@

cntrl@H_403_3@所有控制字符@H_403_3@

digit@H_403_3@所有的数字@H_403_3@

graph@H_403_3@所有可打印字符，不包括空格@H_403_3@

所有的小写字符@H_403_3@

print@H_403_3@所有可打印字符，包括空格@H_403_3@

punct@H_403_3@所有的标点字符@H_403_3@

space@H_403_3@所有的横向或纵向的空白@H_403_3@

所有大写字母@H_403_3@

3.4 字符补集替换@H_403_3@

-c：complement，用SET2替换SET1中没有包含的字符

test$ cat a@H_403_3@txt@H_403_3@

Monday@H_403_3@@H_403_3@09@H_403_3@:@H_403_3@00@H_403_3@

Tuesday@H_403_3@10@H_403_3@

Wednesday@H_403_3@10@H_403_3@11@H_403_3@

Thursday@H_403_3@11@H_403_3@30@H_403_3@

Friday@H_403_3@08@H_403_3@00@H_403_3@

Saturday@H_403_3@07@H_403_3@40@H_403_3@

Sunday@H_403_3@00@H_403_3@

c@H_403_3@"[a-z][A-Z]"@H_403_3@@H_403_3@"#"@H_403_3@s@H_403_3@t@H_403_3@"\n"@H_403_3@

Monday@H_403_3@

Tuesday@H_403_3@

Wednesday@H_403_3@

Thursday@H_403_3@

Friday@H_403_3@

Saturday@H_403_3@

Sunday@H_403_3@

上面代码中 tr -c "[a-z][A-Z]" "#" 表示将除大小字母以外的所有的字符都替换为#。

上面代码可优化为：

cs@H_403_3@"\n"@H_403_3@