File system to rw -automate fstab change

[north-star]

I need to load some newer files on an Embedded RTLinux SBC that boots into a Flight Instrument program. The manufacturer is out of business so is not of much help. During the boot process it looks for a USB stick and a *.sh file that is normally used as an update file. Creating a BASH script I can look at and copy files to the USB (I checked whoami = root) but I cannot copy any file from the USB back to the file system. When I try I get a “File System is Read Only” message. I thought it might be permissions but chmod does not work either. Now after some research (hey, I’m only a couple days into Linux) I found what I believe is the culprit sitting in the /etc/fstab file. The first line is
/dev/hda3 / ext2 ro,noatime 0 1
and I’m pretty sure the ro needs to become rw. The problem is how can I change this? Remember all I have to work with is a *.sh script on a USB stick which exits for a reboot after the script is finished. I think once I can get the file system to rw I can change permissions, copy and overwrite files, etc. and then reset back to ro when I’m done…but how?

[mmatte]

As root,

cp -vp /etc/fstab /etc/fstabOrig

vi (or any text editor) /etc/fstab
change ro to rw in the line for the USB stick
and save the file

[mmatte]

Oops, in a file script as root, the command would be:

sed -e '/\/dev/\/hda3/s/ro/rw/' /etc/fstab

Normally the USB filesystem does not appear in /etc/fstab , you may also try to remove the entry entirely from /etc/fstab

[north-star]

Sorry it took so long to respond...been away for the past month+.

I found the solution to my problem

mount -n -o remount,rw /

this allows a remount with write permissions...chmod /etc/fstab to write permissions and copied a new fstab file with rw instead of ro

after that subsequent reboots allowed me to chmod all required directories and files and copy the new ones I was after.

when finished...reset directories and files to read only and put the original fstab with ro back.

Remember this is all done with a usb stick and bash scripting...no keyboard attached to the embedded sbc