ddns-scripts: improve updater help and legacy syntax error

[dhrm1k]

Fix updater help/error text around legacy invocation and option naming.

Ref: #27737

📦 Package Details

Maintainer: @feckert

Description:
This updates dynamic_dns_updater.sh messaging only:

• correct -N to -n in help/error text
• correct to much commands to too many commands
• add a clearer hint when legacy SECTION VERBOSE style is used (for example opc 0), pointing to -S <section> -v <level> -- start

CC @feckert for review

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🧪 Run Testing Details

• OpenWrt Version: 24.10.4
• OpenWrt Target/Subtarget: x86/64
• OpenWrt Device: Generic (x86_64 VM)

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✅ Formalities

• I have reviewed the CONTRIBUTING.md file for detailed contributing guidelines.

If your PR contains a patch:

• It can be applied using git am
• It has been refreshed to avoid offsets, fuzzes, etc., using

  make package/<your-package>/refresh V=s

[feckert]

That should be first merged to the master branch. After that we can backport this to the stable branches openwrt-24.10 and openwrt-25.12.

Please update the commit message with more context. Is the -N option always wrong? That’s never worked before? What about scripts that already use this option?

Additional make sure you do not exceed the character limit of 75 characters per line.

Use Fixes: <number> so the issue will be auto closed after merge.

[dhrm1k]

That should be first merged to the master branch. After that we can backport this to the stable branches openwrt-24.10 and openwrt-25.12.

Please update the commit message with more context. Is the -N option always wrong? That’s never worked before? What about scripts that already use this option?

Additional make sure you do not exceed the character limit of 75 characters per line.

Use Fixes: <number> so the issue will be auto closed after merge.

Thanks for the review. I updated the commit message with additional context:

• clarified that -N is not universally wrong, but misleading in this code path
• mentioned impact/expectation for existing scripts
• switched to Fixes: #27737
• wrapped lines to <=75 chars

I force-pushed these changes to this PR branch.
If you prefer master-first, I can respin/rebase this PR to target master
(or open a master-targeted PR and link it), then backport to stable branches.
Please confirm your preferred flow.

[feckert]

Ideally, I’d like to have this in the master branch so I can backport it.
But in the master branch, we’ve switched the handling to procd, so '-S $1 -v $2 -- start' is no longer supported or should be used.

[dhrm1k]

Thanks for the clarification.

I am preparing a master-specific version aligned with the procd-based flow. It only fixes incorrect -N references in updater help and error text and does not suggest -S $1 -v $2 -- start and does not add the
-S ... -- start legacy hint.

I will open the master PR first and link it here for backport follow-up.

Fixes: #27737

[dhrm1k]

I opened a master-first PR which matches with procd handling: #29208

After this is merged, I will submit the stable backports.