tac [OPTION]... [FILE]...
!subtitle:功能
将文件的内容顺序逆转，拼接多个文件并打印到标准输出。
文件内顺序逆转，文件之间顺序不变。
!subtitle:类型
可执行文件（/usr/bin/tac），属于 coreutils。
!subtitle:参数
OPTION 选项：
-b, --before - 将分隔符放在前面而不是后面
-r, --regex - 将分隔符当作正则表达式解析
-s, --separator=STRING - 使用 STRING 作为分隔符；默认为换行符（\n）
--help - 显示帮助
--version - 显示版本
FILE - 文件列表；如果没有这个参数或指定为 -，则读取标准输入
$ cat 1.txt 2.txt # 正序查看文件内容
1
2
3
A
B
C
$ tac 1.txt 2.txt # 逆序查看文件内容
3
2
1
C
B
A
| 命令 | 说明 |
|---|---|
| cat | 正序拼接文件内容并打印到标准输出 |
TAC(1) User Commands TAC(1)
NAME
tac - concatenate and print files in reverse
SYNOPSIS
tac [OPTION]... [FILE]...
DESCRIPTION
Write each FILE to standard output, last line first.
With no FILE, or when FILE is -, read standard input.
Mandatory arguments to long options are mandatory for short options
too.
-b, --before
attach the separator before instead of after
-r, --regex
interpret the separator as a regular expression
-s, --separator=STRING
use STRING as the separator instead of newline
--help display this help and exit
--version
output version information and exit
AUTHOR
Written by Jay Lepreau and David MacKenzie.
REPORTING BUGS
GNU coreutils online help: <https://www.gnu.org/software/coreutils/>
Report any translation bugs to <https://translationproject.org/team/>
COPYRIGHT
Copyright © 2023 Free Software Foundation, Inc. License GPLv3+: GNU
GPL version 3 or later <https://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
SEE ALSO
cat(1), rev(1)
Full documentation <https://www.gnu.org/software/coreutils/tac>
or available locally via: info '(coreutils) tac invocation'
GNU coreutils 9.4 April 2024 TAC(1)