scripts/download.pl: pass aria2 config in ENV only

[arenekosreal]

The aria2c command tries to load config from
${XDG_CONFIG_HOME:-${HOME}/.config}/aria2/aria2.conf by default, which may result unexpected behavior.

As a replacement, people can use environment variable ARIA2C_OPTIONS to custom arguments passed to aria2c like curl and wget below.

Signed-off-by: Zhang Hua zhanghuadedn@gmail.com

[aparcar]

Is ARIA2C_OPTIONS something official or did you come up with it? Also why not use the local configuration? Isn't that usually the point of having a local configuration?

[arenekosreal]

@aparcar
No, I just follow the name pattern of curl's CURL_OPTIONS and wget's WGET_OPTIONS to create an environment variable named ARIA2C_OPTIONS.

As far as I know, aria2c will only read environment variable for proxy, like HTTPS_PROXY,HTTP_PROXY and so on. Those environment variables' value can also be override by passing command-line arguments like --https-proxy and --http-proxy

Using the local configuration may be conflict with existing aria2c instance. Take me as an example, I am using that config file for an existing aria2c daemon which will listen a RPC port, if I run the build workflow, the aria2c called by build system will also try to listen that RPC port, of course it will be failed to listen the RPC port because there has already been one listening, the build workflow will also be failed to run due to this.

People have to use a huge number of command-line options if they don't use a config file. As aria2c has an option to custom where the config file is, I must say there may not be so many people use default config path.

[Ansuel]

@zhanghua000 we are sorting some problem with download tool configurable but this LGTM. Will merge when we sort other stuff... while we wait can you fix the title to something more understandable and fix the tag?

Something like scripts/download.pl: permit to pass aria2c config with ENV variables

[arenekosreal]

@Ansuel
I have made my branch rebased and made the tag updated, I think this should meet the requirement now.

[Ansuel]

@zhanghua000 can you rebase this with recent changes?

[arenekosreal]

@Ansuel I have rebased my commit with recent changes.