zsync(1)

💅 zsync(1) — File Transfer manual, but make it cute 💅

okay bestie, welcome to the zsync(1) page from the File Transfer section — it's giving partial/differential file download client over HTTP, and it's actually iconic. Let's go. ✨

✨ NAME ✨

zsync — partial/differential file download client over HTTP. No cap, that's the whole name vibe. 💖

🫶 SYNTAX 🫶

zsync [ -u url ] [ -i inputfile ] [ -o outputfile ] [ { -s | -q } ] [ -k file.zsync ] [ -A hostname=username:password ] { filename | url }

zsync -V

💖 DESCRIPTION 💖

So zsync downloads a file over HTTP. It uses a control file to figure out whether any blocks in the file are already known to the downloader, and then it only downloads the new blocks. Efficiency queen. 👑

You can give either a filename or a URL on the command line — this is the path of the control file for the download. That control file normally has the name of the actual file to download with .zsync appended. (To create this .zsync file you have to have a copy of the target file, so this file should be generated by the person providing the download.) Cute, right? 💅

zsync downloads to your current directory. It looks for any file in the directory of the same name as the file to download. If it finds one, it assumes that's an earlier or incomplete version of the new file to download, and scans this file for any blocks it can use to build the target file. It also looks for a file of the same name with .part appended, so it will automatically find previously interrupted zsync downloads and reuse the data already downloaded. If you know that the local file to use as input has a different name, you must use -i. Periodt. 🎀

zsync retrieves the rest of the target file over HTTP. Once the download is finished, the old version (if the new file wants the same name) is moved aside — a .zs-old extension is appended. The modification time of the file is set to be the same as the remote source file (if specified in the .zsync). It's giving tidy. 🧚

🌈 OPTIONS 🌈

• -A hostname=username:password — Specifies a username and password to be used with the given hostname. -A can be used multiple times (with different hostnames), in cases where e.g. the .zsync file is on a different server from the download, or there are multiple download servers (there could be different auth details for different servers — and zsync never assumes that your password should be sent to a server other than the one named — otherwise redirects would be dangerous!). 🔥
• -i inputfile — Specifies (extra) input files. inputfile is scanned to identify blocks in common with the target file and zsync uses any blocks found. Can be used multiple times. 💖
• -k file.zsync — Indicates that zsync should save the zsync file that it downloads, with the given filename. If that file already exists, then zsync will make a conditional request to the web server, such that it will only download it again if the server's copy is newer. zsync will append .part to the filename for storing it while it is downloading, and will only overwrite the main file once the download is done — and if the download is interrupted, it will resume using the data in the .part file. 🫶
• -o outputfile — Override the default output file name. Slay. 💅
• -q — Suppress the progress bar, download rate and ETA display. Quiet mode, mysterious. 🤫
• -s — Deprecated synonym for -q. She's old, she's deprecated, but she's still here. 💀
• -u url — This specifies the referring URL. If you have a .zsync file locally (if you downloaded it separately, with wget, say) and the .zsync file contains a relative URL, you need to specify where you got the .zsync file from so that zsync knows which server and path to use for the rest of the download. This is analogous to adding a <base href="..."> to a downloaded web page to make the links work. 🦋
• -V — Prints the version of zsync. Iconic. ✨

📁 FILES 📁

No entries are listed in this section in the original — it's just the heading, giving minimalism. 💀

🌸 ENVIRONMENT VARIABLES 🌸

• http_proxy — Should be the [http://]hostname:port for your web proxy, if one is required to access the target web server(s). 🍓

✨ EXAMPLES ✨

Example, bestie:

zsync -i
/var/lib/apt/lists/server.debian.org_debian_dists_etch_main_binary-
i386_Packages http://zsync.moria.org.uk/s/etch/Packages.zsync

👑 AUTHORS 👑

Colin Phipps <cph@moria.org.uk> — the icon who wrote this. 🫶

🔥 SEE ALSO 🔥

• zsyncmake(1) — go check it out, bestie. 💖

💖 that's the zsync(1) manual from Colin Phipps, version 0.6.6 — the original footer has no date, so no invented date, just vibes — periodt. 💖