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This article mainly shows you "how to use the tr command in the Linux system", the content is easy to understand, clear, hope to help you solve your doubts, let the editor lead you to study and learn "how to use the tr command in the Linux system" this article.

Tr conversion, compression, truncation, deletion of characters

Tr [option]. Set1 [set2]

Parameters:

-DMAE, Musi, delete

Delete the characters in string 1 without conversion.

-Scrimson, squeeze, repeats.

Compresses a recurring string into a single string.

-tmam, Musi, truncate, set1.

Truncate the length of string 1 to the length of string 2.

-cmam Mustang

Take the complement of string 1. Requires the character set to be ASCII.

-- help printing help.

-- version displays moderator information.

The escape characters are as follows:

Octal code of\ NNN character

\\ backslash

\ a BELL ringing

\ b spaces

\ c do not print new line characters

\ nNew line

\ r enter

\ t horizontal skipping

\ v firm jump box

Character mode:

CHAR1-CHAR2 means from the characters CHAR1 to CHAR2. For example, a Meli ZJ, a mai Z.

[CHAR*] represents one or several consecutive CHAR.

[CHAR*REPEAT] represents the number of REPEAT CHAR.

[: alnum:] represents all letters and numbers.

[: alpha:] indicates all letters.

[: blank:] represents horizontal spaces.

[: cntrl:] represents a control character.

[: digit:] represents all numbers.

[: graph:] represents printable characters, excluding spaces.

[: lower:] indicates lowercase letters.

[: upper:] indicates uppercase letters.

[: print:] represents printable characters, including spaces.

[: xdigit:] represents a hexadecimal number.

[= CHAR=] indicates CHAR

Example:

(1) remove repeated lowercase characters from oops.txt

The code is as follows:

Tr-s "[a Merz]" result.txt

(2) Delete blank lines

The code is as follows:

Tr-s "[012]"

B.txt

(5) Delete the specified character

A week's schedule. The task is to remove all numbers from it and keep only the date. Dates are in both uppercase and lowercase format. So you need to specify two character ranges [a murz] and [A murz], and command tr-cs "[a murz] [A murz]"[\ 012 *]" to place all strings in each line of the file that are not contained in [a murz] or [Amurz] (all Greek letters) in string 1 and convert them to a new line. The-s option indicates that all new lines are compressed, and-c indicates that all letters remain unchanged. The original file is as follows, followed by the tr command:

The code is as follows:

Tr-cs "[Amurz] [Amurz]" [\ 012*] "

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