tr(translate character)
tr(translate character)功能说明：转换字符。
语 法：tr [-cdst][--help][--version][第一字符集][第二字符集]
补充说明：tr指令从标准输入设备读取数据，经过字符串转译后，输出到标准输出设备。
参 数：
-c或--complerment 取代所有不属于第一字符集的字符。
-d或--delete 删除所有属于第一字符集的字符。
-s或--squeeze-repeats 把连续重复的字符以单独一个字符表示。
-t或--truncate-set1 先删除第一字符集较第二字符集多出的字符。
--help 在线帮助。
--version 显示版本信息。
tr
tr [options] [string1 [string2] ]
Translate characters. Copy standard input to standard output, substituting characters from string1 to string2, or deleting characters in string1.
Options
Complement characters in string1 with respect to ASCII 001-377.
Delete characters in string1 from output.
Squeeze out repeated output characters in string2.
Truncate string1 to the length of string2 before translating.
Print help message and then exit.
Print the version number and then exit.
Special characters
Include brackets ([ ] ) where shown.
Ctrl-G (bell)
Ctrl-H (backspace)
Ctrl-L (form feed)
Ctrl-J (newline)
Ctrl-M (carriage return)
Ctrl-I (tab)
Ctrl-K (vertical tab)
Character with octal value nnn
Literal backslash
All characters in the range char1 through char2. If char1 does not sort before char2, produce an error.
In string2, expand char to the length of string1.
Expand char to number occurrences. [x*4] expands to xxxx, for instance.
Expand to all characters in class, where class can be:
alnum Letters and digits
alpha Letters
blank Whitespace
cntrl Control characters
digit Digits
graph Printable characters except space
lower Lowercase letters
Printable characters
punct Punctuation
space Whitespace (horizontal or vertical)
upper Uppercase letters
xdigit Hexadecimal digits
The class of characters to which char belongs.
Examples
Change uppercase to lowercase in a file:
cat file | tr 'A-Z' 'a-z'
Turn spaces into newlines (ASCII code 012):
tr ' ' ' ' < file
Strip blank lines from file and save in new.file (or use 011 to change successive tabs into one tab):
cat file | tr -s "" " " > new.file
Delete colons from file and save result in new.file:
tr -d : < file > new.file