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tr-转换文件内容.md

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# tr Command
The `tr` command is used to translate or delete characters in a file. It can read from a file or from the standard input, and after the string translation, it outputs the result to the standard output.

## Syntax
```shell
tr [OPTION]... SET1 [SET2]

Options

  • -c, -C, --complement: use the complement of SET1.
  • -d, --delete: delete characters in SET1 without translation.
  • -s, --squeeze-repeats: replace each input sequence of a repeated character listed in SET1 with a single occurrence of that character.
  • -t, --truncate-set1: first truncate SET1 to the length of SET2.
  • --help: display this help and exit.
  • --version: output version information and exit.

Interpretation of escape sequences

... (The content of this section remains unchanged)

Examples

The content of the file.txt file is as follows.

Hello World

Convert all letters in the file to uppercase.

cat file.txt | tr [a-z] [A-Z]
# HELLO WORLD

You can achieve the same using the [:lower] and [:upper] arguments.

cat file.txt | tr [:lower:] [:upper:]
# HELLO WORLD

Convert whitespace characters to tab.

cat file.txt | tr [:space:] "\t"
# Hello   World

Delete all o characters.

cat file.txt | tr -d "o"
# Hell Wrld

Delete all numbers.

echo "My ID is 73535" | tr -d [:digit:]
# My ID is

Extract numbers from a string.

echo "My ID is 73535" | tr -cd [:digit:]
# 73535

Daily Question

https://github.com/WindrunnerMax/EveryDay

References

https://www.runoob.com/linux/linux-comm-tr.html
https://www.tutorialspoint.com/unix_commands/tr.htm
https://www.geeksforgeeks.org/tr-command-in-unix-linux-with-examples/