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Re: couldn't restrict write permission




On Tuesday 11 December 2001 10:16 am, Jonas Holmberg wrote:
> On Tue, 2001-12-11 at 09:51, joost wrote:
> > Hi all,
> > I have a problem logging in with a modem on the devboard_lx. While
> > logging in the login program has to change the ownership of ttyS0, but
> > can't. In a logfile I get the message:
> >
> > Couldn't restrict write permissions to /dev/ttyS0: Read-only file system
>
> Which program does that come from? Does it really have to change
> permission on /dev/ttyS0?

This message is send by the login program. I read somewhere that login and 
getty programs indeed change the ownership of /dev/tty* files when users log 
in. I think I have to make the /dev directory writable, just like the /var 
and /tmp directory. How can I do this?

>
> > How can I give the login program the permission to change the ownership?
> > At an embedded linux newsgroup someone advised me to create a RAM disk,
> > but this is already done right? I can't find really much information
> > about the filesystem.
>
> tmpfs is mounted on /var and /tmp is a symbolic link to /var/tmp so you
> can write to the /var and /tmp directories but it will be lost on
> reboot.
>
> > If I write something to the /etc directory is it directly written
> > to the flash, and does this mean that the flash stops working at +- 1
> > million of those write actions?
>
> There is a limit to how many times you can erase a flash sector (about
> 100000 times i think) so you shouldn't use /mnt/flash for non-important
> logs etc.
>
> Best regards
> /Jonas