tldr 简介
tldr (Too Long; Didn't Read) 是一个开源的命令行工具，提供了简化版的命令使用说明，旨在帮助用户快速掌握命令的常用用法。与 man 相比，tldr 更加简洁，通常展示一些实用的示例，使得用户能够迅速了解命令的基本用途和用法。
tldr 的使用方式非常简单，只需要在 shell 中输入 tldr 后跟要查询的命令名称即可。例如，要查询 ls 命令的简化说明，可以输入 tldr ls ，将显示 ls 命令的常用用法：
(base) root@legion:/home# tldr ls
ls
List directory contents.More information: https://www.gnu.org/software/coreutils/ls.
- List files one per line:
ls -1
- List [a]ll files, including hidden files:
ls -a
- List files with a trailing symbol to indicate file type (directory/, symbolic_link@, executable*, ...):
ls -F
- List [a]ll files in [l]ong format (permissions, ownership, size, and modification date):
ls -la
- List files in [l]ong format with size displayed using [h]uman-readable units (KiB, MiB, GiB):
ls -lh
- List files in [l]ong format, sorted by [S]ize (descending) [R]ecursively:
ls -lSR
- List files in [l]ong format, sorted by [t]ime the file was modified and in [r]everse order (oldest first):
ls -ltr
- Only list [d]irectories:
ls -d */安装
TLDR, man pages summarized by examples in Ubuntu
tldr 可以通过 npm、pip 等包管理工具安装，这个在上面的链接中和 tldr-pages 中都有介绍。此外，通过 apt 也可以安装 tldr：
sudo apt update
sudo apt install tldr如果是 root 用户，可以省略 sudo
我在安装完成后直接执行 tldr 时遇到了 "No tldr entry for xxx" 的错误提示，经查阅发现这是因为首次安装 tldr 需要执行 tldr --update 命令更新 tldr 的本地（数据库）缓存：
(base) root@legion:/home# sudo tldr --update
Cloning into 'tldr'...
remote: Enumerating objects: 115322, done.
remote: Counting objects: 100% (6327/6327), done.
remote: Compressing objects: 100% (623/623), done.
remote: Total 115322 (delta 5999), reused 5736 (delta 5704), pack-reused 108995 (from 1)
Receiving objects: 100% (115322/115322), 27.58 MiB | 664.00 KiB/s, done.
Resolving deltas: 100% (68504/68504), done.
如果执行 tldr --update 提示以下错误：
(base) root@legion:/home# tldr --update
tldr: /root/.local/share/tldr: createDirectory: does not exist (No such file or directory)则先执行 mkdir -p /root/.local/share/tldr 创建该目录，然后再执行 tldr --update 命令即可。
最后再测试 tldr 的功能是否可用。
使用 tldr
- Print the tldr page for a specific command (hint: this is how you got here!):
tldr {{command}}
- Print the tldr page for a specific subcommand:
tldr {{command}} {{subcommand}}
- Print the tldr page for a command in the given [L]anguage (if available, otherwise fall back to English):
tldr --language {{language_code}} {{command}}
- Print the tldr page for a command from a specific [p]latform:
tldr --platform {{android|common|freebsd|linux|osx|netbsd|openbsd|sunos|windows}} {{command}}
- [u]pdate the local cache of tldr pages:
tldr --update
- [l]ist all pages for the current platform and common:
tldr --list
- [l]ist all available subcommand pages for a command:
tldr --list | grep {{command}} | column更新或清除本地缓存
更新本地缓存：tldr --update 或 tldr -u
清除本地缓存：tldr -c
查看指定命令的使用说明
tldr [command-name]
(base) root@legion:/home# tldr systemctl
systemctl
Control the systemd system and service manager.More information: https://www.freedesktop.org/software/systemd/man/systemctl.html.
- Show all running services:
systemctl status
- List failed units:
systemctl --failed
- Start/Stop/Restart/Reload/Show the status a service:
systemctl {{start|stop|restart|reload|status}} {{unit}}
- Enable/Disable a unit to be started on bootup:
systemctl {{enable|disable}} {{unit}}
- Reload systemd, scan for new or changed units:
systemctl daemon-reload
- Check if a unit is active/enabled/failed:
systemctl {{is-active|is-enabled|is-failed}} {{unit}}
- List all service/socket/automount units filtering by running/failed state:
systemctl list-units --type={{service|socket|automount}} --state={{failed|running}}
- Show the contents & absolute path of a unit file:
systemctl cat {{unit}}