Function runShellCommand

src/bin/pgbench/pgbench.c:2738–2837

* Run a shell command. The result is assigned to the variable if not NULL. * Return true if succeeded, or false on error. */

 * Return true if succeeded, or false on error.
 */
static bool
runShellCommand(CState *st, char *variable, char **argv, int argc)
{
	char		command[SHELL_COMMAND_SIZE];
	int			i,
				len = 0;
	FILE	   *fp;
	char		res[64];
	char	   *endptr;
	int			retval;

	/*----------
	 * Join arguments with whitespace separators. Arguments starting with
	 * exactly one colon are treated as variables:
	 *	name - append a string "name"
	 *	:var - append a variable named 'var'
	 *	::name - append a string ":name"
	 *----------
	 */
	for (i = 0; i < argc; i++)
	{
		char	   *arg;
		int			arglen;

		if (argv[i][0] != ':')
		{
			arg = argv[i];		/* a string literal */
		}
		else if (argv[i][1] == ':')
		{
			arg = argv[i] + 1;	/* a string literal starting with colons */
		}
		else if ((arg = getVariable(st, argv[i] + 1)) == NULL)
		{
			pg_log_error("%s: undefined variable \"%s\"", argv[0], argv[i]);
			return false;
		}

		arglen = strlen(arg);
		if (len + arglen + (i > 0 ? 1 : 0) >= SHELL_COMMAND_SIZE - 1)
		{
			pg_log_error("%s: shell command is too long", argv[0]);
			return false;
		}

		if (i > 0)
			command[len++] = ' ';
		memcpy(command + len, arg, arglen);
		len += arglen;
	}

	command[len] = '\0';

	/* Fast path for non-assignment case */
	if (variable == NULL)
	{
		if (system(command))
		{