linux shell 脚本攻略学习7---tr命令详解

tr命令详解

什么是tr命令？tr,translate的简写，translate的翻译：

[trænsˈleit]

vi. 翻译, 能被译出

vt. 翻译, 解释, 转化, 转变为, 调动

在这里用到的意思是转化，转变,转换，在linux下输入tr --help查看一下提示：

amosli@amosli-pc:~$ tr --helpUsage: tr [OPTION]... SET1 [SET2]Translate, squeeze, and/or delete characters from standard input,writing to standard output.  -c, -C, --complement    use the complement of SET1  -d, --delete            delete characters in SET1, do not translate  -s, --squeeze-repeats   replace each input sequence of a repeated character                            that is listed in SET1 with a single occurrence                            of that character  -t, --truncate-set1     first truncate SET1 to length of SET2      --help     display this help and exit      --version  output version information and exitSETs are specified as strings of characters.  Most represent themselves.Interpreted sequences are:  \NNN            character with octal value NNN (1 to 3 octal digits)  \\              backslash  \a              audible BEL  \b              backspace  \f              form feed  \n              new line  \r              return  \t              horizontal tab  \v              vertical tab  CHAR1-CHAR2     all characters from CHAR1 to CHAR2 in ascending order  [CHAR*]         in SET2, copies of CHAR until length of SET1  [CHAR*REPEAT]   REPEAT copies of CHAR, REPEAT octal if starting with 0  [: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 CHARTranslation occurs if -d is not given and both SET1 and SET2 appear.-t may be used only when translating.  SET2 is extended to length ofSET1 by repeating its last character as necessary.  Excess charactersof SET2 are ignored.  Only [:lower:] and [:upper:] are guaranteed toexpand in ascending order; used in SET2 while translating, they mayonly be used in pairs to specify case conversion.  -s uses SET1 if nottranslating nor deleting; else squeezing uses SET2 and occurs aftertranslation or deletion.

Reference:

www.cnblogs.com/amosli/p/3488306.html