How to change the user agent in wget

Changing the HTTP User-Agent in GNU wget helps reproduce browser-gated downloads, compare server behavior across clients, and test request handling without switching tools. A one-off override keeps the change attached to the exact request being tested.

GNU wget normally identifies itself as Wget/version on HTTP and HTTPS requests. Current Wget changes that header with --user-agent=AGENT, and the upstream manual also documents that --user-agent="" suppresses the header completely when a blank value is passed.

User-agent changes can affect returned content, caching layers, bot detection, and rate limits upstream. Keep the override narrow, use /$HOME/.wgetrc/ only when the same identity should apply to later jobs from the same account, and fall back to --no-config when a clean baseline is needed.

1. Check the built-in header first so the comparison starts from the default GNU wget identity.

   $ wget --no-config -qO- https://httpbin.org/user-agent
   {
     "user-agent": "Wget/1.25.0"
   }

   --no-config bypasses both the system startup file and /$HOME/.wgetrc/, so the result shows the built-in header instead of a saved override.

2. Override the header for one request with --user-agent.

   $ wget --no-config --user-agent='MirrorAuditSync/2026.04' -qO- https://httpbin.org/user-agent
   {
     "user-agent": "MirrorAuditSync/2026.04"
   }

   A per-command override is the safest choice for a one-off download, access check, or compatibility test.

3. Suppress the header entirely with an empty value when the target behaves differently without a User-Agent line.

   $ wget --no-config --user-agent='' -qO- https://httpbin.org/user-agent
   {
     "user-agent": null
   }

   A null value from the echo service confirms that current GNU wget omitted the header instead of sending an empty string.

4. Save a default identity in /$HOME/.wgetrc/ only when later wget commands from that account should all use the same value.

   ~/.wgetrc
   # Default HTTP identity for recurring downloads.
   user_agent = MirrorAuditSync/2026.04

   A saved default affects every later HTTP or HTTPS request from that account until the file is changed or bypassed.

5. Run wget without extra header flags and confirm that the saved default is active.

   $ wget -qO- https://httpbin.org/user-agent
   {
     "user-agent": "MirrorAuditSync/2026.04"
   }

   A matching value confirms that the saved startup file is applying the override.

6. Skip the saved profile when a clean baseline is needed again.

   $ wget --no-config -qO- https://httpbin.org/user-agent
   {
     "user-agent": "Wget/1.25.0"
   }