Here simplified to a single curl command:
curl "https://generativelanguage.googleapis.com/v1beta/models/gemini-2.0-flash:generateContent?key=YOUR-API-KEY" \
-H 'Content-Type: application/json' \
-X POST \
-d '{
  "contents": [{
    "parts":[{"text": "Who is the current Chancellor of Germany?"}]
  }],
  "tools": [{
    "googleSearch": {}
  }]
}' | grep -o '"text": "[^"]*"' | sed 's/"text": "\(.*\)"/\1/'

Complete example (REST) from aistudio:
#!/bin/bash
set -e -E
GEMINI_API_KEY="$GEMINI_API_KEY"
MODEL_ID="gemini-2.0-flash"
GENERATE_CONTENT_API="streamGenerateContent"

cat << EOF > request.json
{
    "contents": [
      {
        "role": "user",
        "parts": [
          {
            "text": "INSERT_INPUT_HERE"
          },
        ]
      },
    ],
    "generationConfig": {
      "responseMimeType": "text/plain",
    },
    "tools": [
      {
        "googleSearch": {}
      },
    ],
}
EOF

curl \
-X POST \
-H "Content-Type: application/json" \
"https://generativelanguage.googleapis.com/v1beta/models/${MODEL_ID}:${GENERATE_CONTENT_API}?key=${GEMINI_API_KEY}" -d '@request.json'