Linux/AM1705: GPIO accessing using ECHO command.

can anyone explain why I can't make Gpio pin who's second functionality is UART(UART2_TX=GP5[13], UART1_TX=GP3[10] ) high or low through echo process?

these steps I'm using following atm.
for GPIO number I'm using formula-->gpio_no=(port_no*16) +pin_no.

for UART1_TX=gpio93, UART2_TX=gpio58

example:
echo 93 > /sys/class/gpio/export

echo "out" > /sys/class/gpio/gpio93/direction

echo 1 > /sys/class/gpio/gpio93/value

after entering this command I scope the value, but the pin is unchanged

echo 0 > /sys/class/gpio/gpio93/value

after entering this command I scope the value, but the pin is still unchanged.

both UART_TX pin does n't change it's status at all, on other hand data transmit through /dev/ttyS2 working fine. but using these command other gpio pins are properly changing their status.

SD-CARD issue I'm still unable to resolve it. also,  I went through some mounting process of SD-CARD into ramdisk file as one of TI support suggest and all of them keep getting stuck at some level of the process because there is no /root/dev/sdX node file and file-directory of SDCARD in /root/media/MSDC (my sd card label is MSDC), hence I'm not sure how to access it(connected to MMC port). there are node files name mmcblk0(found on the internet for accessing sdcard) and I tried to mount them into ramdisk file but all of them fail at a certain level of the process.

please go through these process which I tried.

1. after creating a folder via any Linux pc  /home/user1/temp_prcoess/mnt/sdcard.
$ sudo mount /home/user1/temp_prcoess/dev/mmcblk0  /home/user1/temp_prcoess/mnt/sdcard
error: mount: /home/user1/temp_prcoess/dev/mmcblk0 is not a valid block device
I tried with all partition mmcblk0p1 to mmcblk0p7.

2. after creating a folder on my project board's OS  /mnt/sdcard.
$sudo mount /dev/mmcblk0 /mnt/sdcard
error: mount: mounting /dev/mmcblk0 on /mnt/sdcard failed: No such device or address
but there are all mmcblk files present

can you please help me any web-link which I can refer to do the further process or download the file in which everything is present by default so I don't have to go through all these complicated steps.

also, one of the main disadvantages of a RAM disk is that it can only hold data temporarily, in the sense that, if a power failure occurs or if you shutdown or reboot the computer, the data of the RAM disk gets lost, permanently.(i don't have any backup supply or power management mechanism). hence I went through some online document files for storing the data into my flash drive whenever I made any changes in any file but unfortunately these process also getting stuck at some point.

e.g:

process_1:

$sudo mkdir /mnt/RAM_disk_backup
$sudo setfacl -m user:user1:rwx /mnt/RAM_disk_backup
$sudo gedit /lib/systemd/system/ram_disk_load_save.service (open up the text editor)

/**copy the whole code below into text editor and save**/

 [Unit]
Description=A script that saves and restores the data on the RAM disk

Before=umount.target
[Service]

Type=oneshot
User=usr1
ExecStart=/usr/bin/rsync -ar /mnt/RAM_disk_backup/ /mnt/RAM_disk/
ExecStop=/usr/bin/rsync -ar /mnt/RAM_disk/ /mnt/RAM_disk_backup/
RemainAfterExit=yes

[Install]
WantedBy=multi-user.target

$crontab -e
/**Then scroll-down (use the Down-Arrow on your keyboard) and on a new line, copy and paste the below code**/
// * * * * * rsync -ar /mnt/RAM_disk/ /mnt/RAM_disk_backup/
press Ctrl + O[hit enter]
press Ctrl + X[hit enter]

the problem in this process is there is no folder name "systemd" under /lib/ (check screenshot). hence I'm unable to complete the 3rd process(unable to save text editor). also as there is no folder named "rsync" under /usr/bin/ (check screenshot) I'm sure I will get stuck on this issue as well even after resolving the previous issue.