Incompatible with wget from BusyBox

[SteveEdson]

Trying to use this against my Alpine Linux server, but receive the following error:

2019-05-12 15:07:05 INFO	ensuring code-server is updated...
+ mkdir -p /home/steve/.local/share/code-server
+ cd /tmp
+ wget -N https://codesrv-ci.cdr.sh/latest-linux
wget: unrecognized option: N
BusyBox v1.29.3 (2019-01-24 07:45:07 UTC) multi-call binary.

Usage: wget [-c|--continue] [--spider] [-q|--quiet] [-O|--output-document FILE]
	[--header 'header: value'] [-Y|--proxy on/off] [-P DIR]
	[-S|--server-response] [-U|--user-agent AGENT] [-T SEC] URL...

Retrieve files via HTTP or FTP

	--spider	Only check URL existence: $? is 0 if exists
	-c		Continue retrieval of aborted transfer
	-q		Quiet
	-P DIR		Save to DIR (default .)
	-S    		Show server response
	-T SEC		Network read timeout is SEC seconds
	-O FILE		Save to FILE ('-' for stdout)
	-U STR		Use STR for User-Agent header
	-Y on/off	Use proxy
2019-05-12 15:07:06 FATAL	failed to update code-server: exit status 1
---ssh cmd---
ssh  steve@192.168.1.60 /bin/bash
---download script---
set -euxo pipefail || exit 1

mkdir -p ~/.local/share/code-server
cd /tmp
wget -N https://codesrv-ci.cdr.sh/latest-linux
[ -f /tmp/codessh-code-server ] && rm /tmp/codessh-code-server
ln latest-linux /tmp/codessh-code-server
chmod +x /tmp/codessh-code-server

It looks like alpine uses a different wget version, any way to detect and fix this?

Thanks

[teddy-codes]

We could possibly add a check to see if the file exists initially before running wget. This would allow us to omit the -N flag. Thoughts?

[SteveEdson]

What does the -N flag do? Is it possible to use curl instead?

If not, checking for the file first might work yeah.

[teddy-codes]

This is from the documentation:

When running Wget without ‘-N’, ‘-nc’, ‘-r’, or ‘-p’, downloading the same file in the same directory will result in the original copy of file being preserved and the second copy being named ‘file.1’.

I think that just changing the arguments around would allow for this to work properly. I am in the midst of opening a PR for it right now.

[sreya]

The -N flag prevents re-downloading a file if it hasn't been modified

[teddy-codes]

Hm, I don't see that in the docs. Do you have a reference? I am pretty sure it downloads again but overwrites based on the quote that I posted earlier.

[sreya]

GNU Wget 1.17.1 built on linux-gnu

-N,  --timestamping              don't re-retrieve files unless newer local

[teddy-codes]

ah, I just saw that actually. @SteveEdson What version of wget are you using?

Edit:

After the conversation that @sreya92 and I had, the PR that I had produced is becoming obsolete in favor of a newer flag (which is --docker).

[SteveEdson]

It's whatever the default wget is, bundled with BusyBox v1.29.3

[deansheather]

We can use curl with the -z flag to test file modification time. I tested this in alpine:latest with curl installed and it works.

[stokito]

curl is quite heavy and may not be installed. But bb wget allows to pass custom headers so we can imitate it

FILE=example.txt
wget --header="If-Modified-Since:$(date -R -u -r $FILE | sed 's/\UTC/GMT/')" http://example.com/$FILE
# update or not depending on status code 304