使用 Axel 命令行下载器/加速器加速下载 ============================================================ [Axel][7] 是一个轻量级下载程序，它和其他加速器一样，对同一个文件建立多个连接，每个连接下载单独的文件片段以更快地完成下载。 Axel 支持 HTTP、HTTPS、FTP 和 FTPS 协议。它也可以使用多个镜像站点下载单个文件，所以，Axel 可以加速下载高达 40％（大约，我个人认为）。它非常轻量级，因为它没有依赖并且使用非常少的 CPU 和内存。 Axel 一步到位地将所有数据直接下载到目标文件（LCTT 译注：而不是像其它的下载软件那样下载成多个文件块，然后拼接）。 **注意**：不支持在单条命令中下载两个文件。 你还可以尝试其他命令行下载管理器/加速器。 * [aria2 - 超快速下载程序] [1] * [wget - 标准命令行下载程序] [2] * [curl - 命令行下载程序] [3] * [Linux 下的最好的 4 个命令行下载管理器/加速器] [4] 大多数发行版（Debian、Ubuntu、Mint、Fedora、suse、openSUSE、Arch Linux、Manjaro、Mageia 等）都有 axel 包，所以我们可以从发行版官方仓库轻松安装。对于 CentOS/RHEL，我们需要启用 [EPEL Repository][5]。 ``` [在 Debian/Ubuntu/LinuxMint 上安装 Axel] $ sudo apt-get install axel [在 RHEL/CentOS 上安装 Axel] $ sudo yum install axel [在 Fedora 上安装 Axel] $ sudo dnf install axel [在 openSUSE 上安装 Axel] $ sudo zypper install axel [在 Mageia 上安装 Axel] $ sudo urpmi axel [在基于 Arch Linux 的发行版安装 Axel] $ sudo pacman -S axel ``` #### 1) 下载单个文件 以下命令将从给定的 URL 下载文件并存储在当前目录中，下载文件时，我们可以看到文件的信息（建立的连接数、下载速度、下载进度、完成下载所花费的时间以及连接完成的时间）。 ``` # axel https://download.owncloud.org/community/owncloud-9.0.0.tar.bz2 Initializing download: https://download.owncloud.org/community/owncloud-9.0.0.tar.bz2 File size: 22678208 bytes Opening output file owncloud-9.0.0.tar.bz2 Starting download [ 0%] .......... .......... .......... .......... .......... [ 146.7KB/s] [ 0%] .......... .......... .......... .......... .......... [ 267.0KB/s] [ 0%] .......... .......... .......... .......... .......... [ 373.9KB/s] [ 0%] .......... .......... .......... .......... .......... [ 406.9KB/s] [ 0%] .......... .......... .......... .......... .......... [ 487.5KB/s] [ 1%] .......... .......... .......... .......... .......... [ 572.6KB/s] [ 1%] .......... .......... .......... .......... .......... [ 650.7KB/s] [ 1%] .......... .......... .......... .......... .......... [ 649.3KB/s] [ 1%] .......... .......... .......... .......... .......... [ 718.1KB/s] [ 2%] .......... .......... .......... .......... .......... [ 769.3KB/s] [ 2%] .......... .......... .......... .......... .......... [ 838.7KB/s] [ 2%] .......... .......... .......... .......... .......... [ 866.0KB/s] Connection 0 finished . . [ 99%] .......... .......... .......... .......... .......... [5721.0KB/s] Connection 2 finished [ 99%] .......... .......... .......... .......... .......... [5733.4KB/s] Connection 1 finished [ 99%] .......... .......... .......... .......... .......... [5745.4KB/s] [100%] .......... .......... .......... .......... ...... Downloaded 21.6 megabytes in 3 seconds. (5755.94 KB/s) ``` #### 2) 用不同的名称保存文件 要使用其他名称来保存文件，启动下载时可以添加 `-o`（小写字母）选项和文件名。这里我们使用文件名 `owncloud.tar.bz2` 来保存文件。 ``` # axel -o cloud.tar.bz2 https://download.owncloud.org/community/owncloud-9.0.0.tar.bz2 Initializing download: https://download.owncloud.org/community/owncloud-9.0.0.tar.bz2 File size: 22678208 bytes Opening output file cloud.tar.bz2 Starting download [ 0%] .......... .......... .......... .......... .......... [ 143.0KB/s] [ 0%] .......... .......... .......... .......... .......... [ 264.1KB/s] [ 0%] .......... .......... .......... .......... .......... [ 309.8KB/s] [ 0%] .......... .......... .......... .......... .......... [ 406.3KB/s] [ 0%] .......... .......... .......... .......... .......... [ 495.4KB/s] [ 1%] .......... .......... .......... .......... .......... [ 586.3KB/s] [ 1%] .......... .......... .......... .......... .......... [ 673.1KB/s] [ 1%] .......... .......... .......... .......... .......... [ 647.1KB/s] [ 1%] .......... .......... .......... .......... .......... [ 721.1KB/s] [ 2%] .......... .......... .......... .......... .......... [ 781.3KB/s] Connection 2 finished . . Connection 0 finished [ 98%] .......... .......... .......... .......... .......... [6221.9KB/s] [ 98%] .......... .......... ..... Connection 1 finished ,,,,,,,,,, ,,,,,,,,,, ,,,,,..... .......... .......... [6145.6KB/s] [ 99%] .......... .......... .......... .......... .......... [6159.2KB/s] [ 99%] .......... .......... .......... .......... .......... [6172.0KB/s] [ 99%] .......... .......... .......... .......... .......... [5977.9KB/s] [ 99%] .......... .......... .......... .......... .......... [5989.6KB/s] [100%] .......... .......... .......... .......... ...... Downloaded 21.6 megabytes in 3 seconds. (6001.05 KB/s) ``` #### 3) 限制下载速度 默认情况下 axel 以字节/秒为单位设置下载文件的最大速度。当我们的网络连接速度较慢时，可以使用此选项。只需添加 `-s` 选项，后面跟字节值。这里我们要限速 `512 KB/s` 下载一个文件。 ``` # axel -s 512000 https://download.owncloud.org/community/owncloud-9.0.0.tar.bz2 Initializing download: https://download.owncloud.org/community/owncloud-9.0.0.tar.bz2 File size: 22678208 bytes Opening output file owncloud-9.0.0.tar.bz2 Starting download [ 0%] .......... .......... .......... .......... .......... [ 141.5KB/s] [ 0%] .......... .......... .......... .......... .......... [ 266.1KB/s] [ 0%] .......... .......... .......... .......... .......... [ 308.0KB/s] [ 0%] .......... .......... .......... .......... .......... [ 405.9KB/s] [ 0%] .......... .......... .......... .......... .......... [ 496.7KB/s] [ 1%] .......... .......... .......... .......... .......... [ 526.4KB/s] [ 1%] .......... .......... .......... .......... .......... [ 507.0KB/s] [ 1%] .......... .......... .......... .......... .......... [ 505.6KB/s] [ 1%] .......... .......... .......... .......... .......... [ 504.8KB/s] [ 2%] .......... .......... .......... .......... .......... [ 503.9KB/s] [ 2%] .......... .......... .......... .......... .......... [ 503.4KB/s] . . [ 99%] .......... .......... .......... .......... .......... [ 497.0KB/s] [ 99%] .......... .......... .......... .......... .......... [ 496.9KB/s] [100%] .......... .. Connection 0 finished ,,,,,,,,,, ,,..... Connection 1 finished Connection 3 finished ,,,,,,,,,, ,,,,,,,... .......... .......... ...... Downloaded 21.6 megabytes in 44 seconds. (494.54 KB/s) ``` #### 4) 限制连接数 axel 默认建立 4 个连接以从不同的镜像获取文件。此外，我们可以通过使用 `-n` 选项添加更多的连接，后跟连接数 `10` 来提高下载速度。保险起见，我们添加了十个连接，但不幸的是，它花了更多时间来下载文件。 ``` # axel -n 10 https://download.owncloud.org/community/owncloud-9.0.0.tar.bz2 Initializing download: https://download.owncloud.org/community/owncloud-9.0.0.tar.bz2 File size: 22678208 bytes Opening output file owncloud-9.0.0.tar.bz2 Starting download [ 0%] .......... .......... .......... .......... .......... [ 140.8KB/s] [ 0%] .......... .......... .......... .......... .......... [ 265.7KB/s] [ 0%] .......... .......... .......... .......... .......... [ 305.4KB/s] [ 0%] .......... .......... .......... .......... .......... [ 402.1KB/s] [ 0%] .......... .......... .......... .......... .......... [ 496.3KB/s] [ 1%] .......... .......... .......... .......... .......... [ 522.1KB/s] [ 1%] .......... .......... .......... .......... .......... [ 567.5KB/s] [ 1%] .......... .......... .......... .......... .......... [ 640.5KB/s] [ 1%] .......... .......... .......... .......... .......... [ 710.8KB/s] [ 2%] .......... .......... .......... .......... .......... [ 780.5KB/s] . . [ 98%] .......... .......... .......... .......... .......... [7544.9KB/s] [ 98%] .......... .......... .......... .......... .......... [7557.9KB/s] [ 98%] .......... .......... .......... .......... .......... [7570.4KB/s] [ 98%] .......... .......... .......... .......... .......... [7495.3KB/s] [ 99%] .......... .......... .......... .......... ...... Connection 2 finished ,,,,,,,,,, ,,,,,,,,,, ,,,,,,,,,, ,,,,,,,,,, ,,,,,,.... [7311.6KB/s] [ 99%] .......... .......... .......... .......... .......... [7318.9KB/s] [ 99%] .......... .......... .......... .......... .......... Connection 9 finished ,,,,,,,,,, ,,,,,,,,,, ,,,,,,,,,, ,,,,,,,,,, ,,,,,,,,,, [7331.0KB/s] [ 99%] .......... .......... .......... .......... Connection 3 finished ,,,,,,,,,, ,,,,,,,,,, ,,,,,,,,,, ,,,,,,,,,, .......... [4300.7KB/s] [100%] .......... .......... .......... .......... ...... Downloaded 21.6 megabytes in 5 seconds. (4109.41 KB/s) ``` #### 5) 恢复未完成的下载 axel 默认具有恢复未完成的下载的行为。Axel 在下载文件时定期更新状态文件（扩展名为 `.st`）。由于某些原因，下载中途停止了？不用担心，只要使用相同的 axel 命令，它将会检查 `file` 和 `file.st`，如果找到，它会从停止处恢复下载。 ``` # axel https://download.owncloud.org/community/owncloud-9.0.0.tar.bz2 Initializing download: https://download.owncloud.org/community/owncloud-9.0.0.tar.bz2 File size: 22678208 bytes Opening output file owncloud-9.0.0.tar.bz2 Starting download [ 0%] .......... .......... .......... .......... .......... [ 140.8KB/s] [ 0%] .......... .......... .......... .......... .......... [ 265.7KB/s] [ 0%] .......... .......... .......... .......... .......... [ 305.4KB/s] [ 0%] .......... .......... .......... .......... .......... [ 402.1KB/s] [ 0%] .......... .......... .......... .......... .......... [ 496.3KB/s] [ 1%] .......... .......... .......... .......... .......... [ 522.1KB/s] [ 1%] .......... .......... .......... .......... .......... [ 567.5KB/s] [ 1%] .......... .......... .......... .......... .......... [ 640.5KB/s] [ 1%] .......... .......... .......... .......... .......... [ 710.8KB/s] [ 2%] .......... .......... .......... .......... .......... [ 780.5KB/s] . . [ 84%] .......... .......... .......... .......... .......... [7100.7KB/s] [ 84%] .......... .......... .......... .......... .......... [7104.3KB/s] [ 84%] .......... .......... .......... .^C Downloaded 18.3 megabytes in 2 seconds. (7009.79 KB/s) ``` 上面的输出清晰地显示了在下载断开时有两个文件 `owncloud-9.0.0.tar.bz2` 和 `owncloud-9.0.0.tar.bz2.st`。当重新开始下载时，它会从停止处开始下载。 ``` # ls -lh total 19M -rw------- 1 root root 22M Dec 27 08:33 owncloud-9.0.0.tar.bz2 -rw------- 1 root root 44 Dec 27 08:33 owncloud-9.0.0.tar.bz2.st # axel https://download.owncloud.org/community/owncloud-9.0.0.tar.bz2 Initializing download: https://download.owncloud.org/community/owncloud-9.0.0.tar.bz2 File size: 22678208 bytes Opening output file owncloud-9.0.0.tar.bz2 State file found: 19180828 bytes downloaded, 3497380 to go. Starting download ,,,,,,,,,, ,,,,,,,,,, ,,,,,,,,,, ,......... .......... [ 66.5KB/s] [ 84%] .......... .......... .......... .......... .......... [ 186.0KB/s] [ 85%] .......... .......... .......... .......... .......... [ 241.7KB/s] [ 85%] .......... .......... .......... .......... .......... [ 335.6KB/s] [ 85%] .......... .......... .......... .......... .......... [ 351.5KB/s] [ 85%] .......... .......... .......... .......... .......... [ 427.1KB/s] [ 85%] .......... .......... .......... .......... .......... [ 427.4KB/s] [ 86%] .......... .......... .......... .......... .......... [ 491.5KB/s] . . [ 98%] ... Connection 0 finished ,,,....... .......... .......... .......... .......... [2106.6KB/s] [ 99%] .......... .......... .......... .......... .......... [2140.5KB/s] [ 99%] .......... .......... .......... .......... .......... [2172.4KB/s] [ 99%] .......... .......... .......... .......... .......... [2203.2KB/s] [ 99%] .......... .......... .......... .......... .......... [2236.2KB/s] [100%] .......... .......... .......... .......... ...... Downloaded 3415.4 kilobytes in 1 second. (2264.93 KB/s) ``` #### 6) 不显示文件下载进度 如果你不想要看到文件的下载进度，只要在 axel 命令中加入 `-q` 选项。 ``` # axel -q https://download.owncloud.org/community/owncloud-9.0.0.tar.bz2 ``` #### 7) 替换进度条 如果你不喜欢默认的进度条，你可以使用 `-a` 选项来替换进度条。 ``` # axel -a https://download.owncloud.org/community/owncloud-9.0.0.tar.bz2 Initializing download: https://download.owncloud.org/community/owncloud-9.0.0.tar.bz2 File size: 22678208 bytes Opening output file owncloud-9.0.0.tar.bz2 Starting download [ 66%] [......0 ...1 ..........2 ...........3] [ 5.8MB/s] [00:01]^C Downloaded 14.3 megabytes in 2 seconds. (5916.11 KB/s) ``` 我们中断了上面的下载，以便在下载文件时能清楚地显示替代进度条状态。一旦文件成功下载后，你可以看到相同的输出，如下所示。 ``` # axel -a https://download.owncloud.org/community/owncloud-9.0.0.tar.bz2 File size: 22678208 bytes Opening output file owncloud-9.0.0.tar.bz2 Starting download Connection 2 finished ] Connection 1 finished ] Connection 3 finished ] Connection 0 finished ] Downloaded 21.6 megabytes in 4 seconds. (5062.32 KB/s) ``` #### 8) 了解关于 axel 的更多信息 如果你想要了解更多关于 axel 的选项，只需要进入它的手册。 ``` # man axel 或者 # axel --help ``` 享受吧。。。) -------------------------------------------------------------------------------- via: http://www.2daygeek.com/axel-command-line-downloader-accelerator-for-linux/ 作者：[Magesh Maruthamuthu][a] 译者：[geekpi](https://github.com/geekpi) 校对：[jasminepeng](https://github.com/jasminepeng) 本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 [a]:http://www.2daygeek.com/author/magesh/ [1]:http://www.2daygeek.com/aria2-command-line-download-utility-tool/ [2]:http://www.2daygeek.com/wget-command-line-download-utility-tool/ [3]:http://www.2daygeek.com/aria2-command-line-download-utility-tool/ [4]:https://linux.cn/article-8124-1.html [5]:https://linux.cn/article-2324-1.html [6]:http://www.2daygeek.com/author/magesh/ [7]:https://axel.alioth.debian.org/