Source

File: wp-admin/includes/class-wp-filesystem-ssh2.php

public function put_contents( $file, $contents, $mode = false ) {
		$ret = file_put_contents( $this->sftp_path( $file ), $contents );

		if ( strlen( $contents ) !== $ret ) {
			return false;
		}

		$this->chmod( $file, $mode );

		return true;
	}