Run the script with -o argument pointing to the mount point of above mentioned card

can you please give me the command line in detail with an example possibly with apalis imx6

Find the mount point of your SD/uSD card by e.g. using df or lsblk:

[user@host ~]$ df
Filesystem              1K-blocks      Used Available Use% Mounted on
/dev/mmcblk0p1            7582228   2808272   4773956  38% /media/user
[user@host ~]$ lsblk
NAME                         MAJ:MIN RM   SIZE RO TYPE  MOUNTPOINT
mmcblk0                      179:0    0   7.3G  0 disk  
└─mmcblk0p1                  179:1    0   7.3G  0 part  /media/user

Run the script with the -o argument pointing to the mount point of the SD card. For example assuming the SD card is mounted at /media/user:

./ -o /media/user/

At this point the SD/uSD card should contain U-Boot, the flash scripts and the root file system image.