Function exec_command_encoding

src/bin/psql/command.c:1260–1294

* \encoding -- set/show client side encoding */

 * \encoding -- set/show client side encoding
 */
static backslashResult
exec_command_encoding(PsqlScanState scan_state, bool active_branch)
{
	if (active_branch)
	{
		char	   *encoding = psql_scan_slash_option(scan_state,
													  OT_NORMAL, NULL, false);

		if (!encoding)
		{
			/* show encoding */
			puts(pg_encoding_to_char(pset.encoding));
		}
		else
		{
			/* set encoding */
			if (PQsetClientEncoding(pset.db, encoding) == -1)
				pg_log_error("%s: invalid encoding name or conversion procedure not found", encoding);
			else
			{
				/* save encoding info into psql internal data */
				pset.encoding = PQclientEncoding(pset.db);
				pset.popt.topt.encoding = pset.encoding;
				setFmtEncoding(pset.encoding);
				SetVariable(pset.vars, "ENCODING",
							pg_encoding_to_char(pset.encoding));
			}
			free(encoding);
		}
	}
	else
		ignore_slash_options(scan_state);

	return PSQL_CMD_SKIP_LINE;
}

/*
 * \errverbose -- display verbose message from last failed query