求助！官网提供的解压缩工具不可用报错！

root@84a47a1b67e1:/root/backup >>> ls 16-03-16 9:11
hins394821_xtra_20160314072632.tar.gz rds_backup_extract.sh
root@84a47a1b67e1:/root/backup >>> sh rds_backup_extract.sh -f hins394821_xtra_20160314072632.tar.gz 16-03-16 9:11
rds_backup_extract.sh: 76: rds_backup_extract.sh: [[: not found
chmod: cannot access '/tmp/rds_backup_tools/xbstream': No such file or directory
Error: unknown backup file format, only xxx.tar.gz and xxx.xb.gz file format are supported.

Extract RDS data backup file.

Usage:

rds_backup_extract.sh -f backupfile [-C dest_dir]

Options:

-h,              Dispaly this help and exit.
-f, file         Extract the specified backup file (only support tar.gz and xb.gz file format).
-C, directory    Extract to the specified directory (default is current directory).

root@84a47a1b67e1:/root/backup >>>