fix: cross platform compatibility

scripts/l2-explorer/l2-blockscout-set-env.sh

@@ -23,6 +23,19 @@ L1_SYSTEM_CONFIG_ADDRESS=$(jq -r '.l1_system_config_address' "$ROLLUP_JSON")
 OUTPUT_ORACLE_ADDRESS=$(jq -r '.L2OutputOracleProxy' "$OP_DEPLOYMENTS_JSON_PATH")
 
 # Update .explorer.env file
-sed -i "s/^L1_SYSTEM_CONFIG_CONTRACT=.*/L1_SYSTEM_CONFIG_CONTRACT=$L1_SYSTEM_CONFIG_ADDRESS/" "$ENV_FILE"
-sed -i "s/^L1_OUTPUT_ORACLE_CONTRACT=.*/L1_OUTPUT_ORACLE_CONTRACT=$OUTPUT_ORACLE_ADDRESS/" "$ENV_FILE"
+update_env_var() {
+    local key="$1"
+    local value="$2"
+    local file="$3"
+    if grep -q "^$key=" "$file"; then
+        # If the key exists, replace the line
+        sed -i.bak "s|^$key=.*|$key=$value|" "$file" && rm "${file}.bak"
+    else
+        # If the key doesn't exist, append it
+        echo "$key=$value" >> "$file"
+    fi
+}
+update_env_var "L1_SYSTEM_CONFIG_CONTRACT" "$L1_SYSTEM_CONFIG_ADDRESS" "$ENV_FILE"
+update_env_var "L1_OUTPUT_ORACLE_CONTRACT" "$OUTPUT_ORACLE_ADDRESS" "$ENV_FILE"
+
 echo "Updated .explorer.env file for Blockscout"