my filesystem is read only ie in this file /etc/sysconfig/readonly
READONLY=YES
this is bydefault NO but i do READONLY=YES and reboot
now my system is boot properly but no any file create and modify and no command run like useradd, cp, ifconfig etc.
how can modify this file ie /etc/sysconfig/readonly
READONLY=NO
please tell me any person
thank you in advance.

Boot using a LiveCD, mount the partition and edit the file.

Have you tried:

mount -o remount,rw /mountpoint

The above will work. Alternatively, if your system uses GRUB as its bootloader, there might be a quicker way:

• At the GRUB menu, select the menu entry for your Linux install and type 'e' to edit the entry.
  
• Select the line beginning with the word 'kernel' and type 'e' again to edit.
  
• Add the word 'single' to the end of the line, hit enter, and type 'b' to boot.

You're now in single-user mode - logged in as root with minimal services running. Although whether this will allow you to mount your filesystem rw I'm not certain. Just try to edit the file in a console-mode text editor, e.g. emacs (use ctrl+x followed by ctrl+s to save, and ctrl+x followed by ctrl+c to exit), or vi if you know what you're doing but I don't recommend it!

Oh, you can probably get into single-user mode with LILO or another bootloader as well, just do a quick google.

And that's quicker than a simple remount?

Take the simple path...

mount -o remount,rw /

The filesystem is now mounted read/write and you can make any modifications required.

Er, oh yeah, oops. Do it tim's way

I've sent myself down the rabbit hole more than once when the direct path was right in front of me :-)

check this out.
cat /etc/fstab
tuxfiles.org/linuxhelp/fstab.html

hi,
for hu8mypho
editing /etc/fstab will make your customization as a default setting for the system, and for security issues, you shouldn't make your mount wrof course not for the root user to do so here is an example :

/dev/sda4 /mnt/mnt-1 defaults 0 0

if you have a different character set you may add
",iocharset=utf8" just after defaults if you have another lang other than english.
for these two zeros they mean that no one can read write except the root user

Hi yen_yang, that's not what the two zeroes mean. From man fstab:

You can't set the user/group/other permission bits from fstab, except in the case of a filesystem which doesn't support permission bits (in which case you can set a mask applying to all files) - presumably this doesn't apply to the OP's / filesystem. You can set ro/rw settings for all users, but the OP had the ro setting in a different file.

My apologies, I assumed that user was root, and was just having difficulty with ro on boot. This suggested to me that the file system that was hung under /etc/sysconfig/<readonly> - mount point.

rather manually mount/umount, fstab could be a permanent solution if truly intended for r/w.

hi OpenSauce, i do aplogize for that mistake, and thanx so much for your clarification, i think i should have meant the umask values added after defaults

tim914:

Currently my filesystem is mounted as indicated in the following output from the mount command:

/dev/sda3 on /run/media/enowak/Seagate_2TB-1 type fuseblk (ro,nosuid,nodev,relatime,user_id=0,group_id=0,default_permissions,allow_other,blksize=4096,uhelper= udisks2)

I did as you suggested by issuing the following command:

sudo mount -o remount,rw /dev/sda3

I then issued the mount command and got:

/dev/sda3 on /run/media/enowak/Seagate_2TB-1 type fuseblk (rw,nosuid,nodev,relatime,user_id=0,group_id=0,default_permissions,allow_other,blksize=4096,uhelper= udisks2)

ro got changed to rw. I thought this would do the trick.
Unfortunately I still can't create a new file in the filesystem Seagate_2TB-1.
For example I created a file with LibreOffice Writer and tried to save it in Seagate_2TB-1.
I got the following error message:

Error saving the document Untitled 1:
/run/media/enowak/Seagate_2TB-1/Miscellaneous/Untitled 1.odt does not exist.

There must be some other options besides ro that have to be changed.