Shell Script (iv)

Shell Script (iv)

(7) TR command

#实现字符转换功能

#-c string: Inverse string character set, that is, all character sets except for the string

#-d string: Delete all occurrences of characters in string

#-s: Deletes all occurrences of a sequence of characters, leaving only one

#删除所有数字

Tr-d "[[:d Igit:]]" < name.txt

Tr-d 0-9 < Name.txt

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#所有小写字母转换成大写字母

TR "[A-Z]" "[A-Z]" < name.txt

TR "[[: Lower:]]" "[[: Upper:]]" < name.txt

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#-c usage, replaces all non-26 letters with newline characters, and repeated newline characters are compressed into 1 newline characters

Tr-cs "[A-z][a-z]" "[\ n]" < Name.txt

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#支持使用字符 * Digital mode, such as N*4 for n appears 4 times

#-s is a continuous repetition of letters, numbers compressed into 1

Tr-s "[a-z][a-z],[[:d Igit:]]" < num.txt

#结果同1行的test, T and T are not duplicates.

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3. Regular Expressions

(1) match: "*", "^", ".", "$", etc.

"*": 0 or more ordinary characters before the * character

".": matches any character

"^": matches the beginning of the line, placed in the [] character set to indicate the inverse

"$": Match line end

"[]": Match character Set

"\": Escape character, shielding the special meaning of a meta-character

"\<\>": Exact match symbol

"\{n\}": matches the preceding character n times

"\{n,\}": matches the preceding character at least n times

"\{n,m\}": Matches the previous character appears n-m times

(2) Extension: "?", "+", "()", "|"

"?": Match 0 or 1 ordinary characters before the? character

"+": match 1 or more of the ordinary characters before the + character

"()": Represents a character set

"|": means "or" to match an optional set of characters

(3) grep command

#支持正则表达式的多用途文本搜索工具

#-c: Outputs only the number of matching rows;-I: Ignores case when searching;-H: Does not display filenames when querying multiple files;

#-l: Lists only matching file names and does not list specific matching lines;-N: Lists the matches and line numbers;

#-s: does not display error messages for nonexistent or no matching files;-V: Displays all lines that do not contain matching text;

#-w: Match thing word;-x: Match the row;-r: Recursive query, search subdirectory;-Q: Suppresses output of any result to exit

#状态来表示搜索是否成功; b: Prints the offset of the header of the matching leading file, in bytes;

#-o: Used in conjunction with-B to print the offset of the matching word from the file header, in bytes;-e: Using extended expressions

#-f: Do not use regular expressions to search the literal meaning of a string

#需要特别注意的是, the number of occurrences refers to successive occurrences, not the total number of occurrences!!!

# "*" usage, the letter M appears at least 0 times

grep "Nam*3" Name.txt

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#"." Usage, search for "na any character 3"

grep "Na.3" Name.txt

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#搜索以A开头的行, and lose the travel number

Grep-n ^a A.txt

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# "$" usage, search for lines ending with 10

grep 10$ Name.txt

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# "[]" usage, search for an arbitrary lowercase letter followed by an arbitrary number of lines

grep [a-z][0-9] Name.txt

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# "\" usage, search for lines beginning with *

grep ^\* Name.txt

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# "\<\>" usage, search for rows that appear Name3

grep "\<name3\>" Bkname.txt

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# "\<n,\>" usage, search number 0 appears at least 5 times

grep "0\{5,}" Bkname.txt

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# "\<n,m\>" usage, search number 7 appears 2 times to 3 rows

grep "7\{2,3\}" Name.txt

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# "?", "+", "()" and "|" is a regular expression extension, you need to use the-e parameter

#"?" Usage, search for lines that contain nu or num

Grep-e "num?" Bkname.txt

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# "+" usage, search for a line with the letter T appearing at least 1 times

Grep-e "t+" Bkname.txt

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# "()" and "|" Use combination to search for lines that contain nu or num

Grep-e "(nu|num)" Bkname.txt

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#多文件搜索包含name1的行, and lose the travel number

grep name1 Name.txt Num.txt

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#显示匹配行前后2行

Grep-2 name2 Name.txt

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#显示匹配行的

GREP-A2 name2 Name.txt

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#-c: Usage, counting blank lines

Grep-c ^$/etc/httpd/conf/httpd.conf/

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#-i: Ignoring case

Grep-i name Bkname.txt

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#-h: Multiple file queries do not display file names

Grep-h Test Bkname.txt Num.txt

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#-n: Display matching lines and line numbers

Grep-n Test Bkname.txt

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#-w: the string to be searched must be a complete word;

#-x: Displays fully compliant rows, and the searched string must be a separate line

Grep-w Test Bkname.txt

Grep-x Test Bkname.txt

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Shell Script (iv)