How To Resume wget Downloads

I'm downloading CentOS 8 Stream as we speak, and it's a large enough ISO file – standard 8GB DVD image. I stopped download because I wanted to restart it in a tmux session, and realised that it's a good opportunity to explain how this works.

How To Start Wget Download

Assuming you go to the CentOS Stream Download page and pick an image to download, you'll end up with a download URL like this:

http://ftp.heanet.ie/pub/centos/8-stream/isos/x86_64/CentOS-Stream-x86_64-dvd1.iso

Using wget, here's how you can start downloading it:

greys@redhat:/dist/iso $ wget http://ftp.heanet.ie/pub/centos/8-stream/isos/x86_64/CentOS-Stream-x86_64-dvd1.iso
--2019-09-30 14:35:36--  http://ftp.heanet.ie/pub/centos/8-stream/isos/x86_64/CentOS-Stream-x86_64-dvd1.iso
Resolving ftp.heanet.ie (ftp.heanet.ie)… 87.44.34.235
Connecting to ftp.heanet.ie (ftp.heanet.ie)|87.44.34.235|:80… connected.
HTTP request sent, awaiting response… 200 OK
Length: 8572108800 (8.0G) [application/octet-stream]
Saving to: ‘CentOS-Stream-x86_64-dvd1.iso’
CentOS-Stream-x86_64-dvd1.iso  1%[+      ] 100.83M  1.77MB/s    eta 73m 43s
^C

At any time you can press Ctlr+C to stop the process. A file with unfinished download will be left in the current directory:

greys@redhat:/dist/iso $ ls -ald *iso
-rw-rw-r--. 1 greys 118453636 Sep 30 14:37 CentOS-Stream-x86_64-dvd1.iso

And if you just re-run the same wget command, your download will actually restart:

greys@redhat:/dist/iso $ wget http://ftp.heanet.ie/pub/centos/8-stream/isos/x86_64/CentOS-Stream-x86_64-dvd1.iso
--2019-09-30 14:44:08--  http://ftp.heanet.ie/pub/centos/8-stream/isos/x86_64/CentOS-Stream-x86_64-dvd1.iso
Resolving ftp.heanet.ie (ftp.heanet.ie)… 87.44.34.235
Connecting to ftp.heanet.ie (ftp.heanet.ie)|87.44.34.235|:80… connected.
HTTP request sent, awaiting response… 200 OK
Length: 8572108800 (8.0G) [application/octet-stream]
Saving to: ‘CentOS-Stream-x86_64-dvd1.iso.1’
CentOS-Stream-x86_64-dvd1.iso.1  0%[+      ]  24.88M   775KB/s    eta 2h 13m
^C

If you notice though, the download restarts with a different filename: CentOS-Stream-x86_64-dvd1.iso.1 in my case. So wget kept your previous download attempt and started a new one:

greys@redhat:/dist/iso $ ls -ald iso
-rw-rw-r--. 1 greys 118453636 Sep 30 14:37 CentOS-Stream-x86_64-dvd1.iso
-rw-rw-r--. 1 greys  26088163 Sep 30 14:44 CentOS-Stream-x86_64-dvd1.iso.1