Linux command
tac 命令
文件
复制后可按需替换文件名、目录或参数。
常用示例
Reverse lines
tac [file.txt]
Reverse lines
tac [file1.txt] [file2.txt]
Reverse with custom separator
tac -s "[separator]" [file.txt]
Reverse with regex separator
tac -r -s "[pattern]" [file.txt]
Reverse stdin
cat [file.txt] | tac
Reverse before separator
tac -b -s "[separator]" [file.txt]
说明
tac concatenates and prints files in reverse, line by line. The name is "cat" spelled backwards, reflecting its reversed functionality. By default, tac uses newline as the record separator, reversing line order. Custom separators can be specified, making it useful for reversing records in various file formats. The tool is handy for viewing log files (newest first), reversing sorted output, or processing data that needs to be in reverse order.
参数
- -b, --before
- Attach separator before instead of after record.
- -r, --regex
- Interpret separator as regular expression.
- -s _string_, --separator= _string_
- Use string as separator instead of newline.
- --help
- Display help information.
- --version
- Display version information.
FAQ
What is the tac command used for?
tac concatenates and prints files in reverse, line by line. The name is "cat" spelled backwards, reflecting its reversed functionality. By default, tac uses newline as the record separator, reversing line order. Custom separators can be specified, making it useful for reversing records in various file formats. The tool is handy for viewing log files (newest first), reversing sorted output, or processing data that needs to be in reverse order.
How do I run a basic tac example?
Run `tac [file.txt]` in a terminal, then adjust file names, paths, flags, or remote targets for your system.
What does -b, --before do in tac?
Attach separator before instead of after record.