Remove a line in fstab

[betweendayandnight]

I thought it would be easier for me to mount flash drives automatically if I did the following to fstab:

/dev/sd1i /mnt/usb

(sd1i is found from sysctl hw.disknames)

I rebooted the box with the USB 3.0 flash drive still inserted in the USB 3.0 port.

During the boot process, the following errors were detected:

/dev/rsd1i: BAD SUPER BLOCK: MAGIC NUMBER WRONG
/dev/rsd1i: Unexpected inconsistency: Run fsck_ffs manually
The following file system had an unexpected inconsistency: ffs: /dev/rsd1i (/mnt/usb)
Automatic file system check failed; help!
Enter pathname of shell or RETURN for sh:

I checked out the article "How to use ed to edit /etc/fstab in single user mode" (http://www.openbsdsupport.org/ed_and_fstab.html) which discussed about how to use ed to modify lines but not to delete them.

[jggimi]

Hello, and welcome!

You can still use ed(1), just put a "#" -- called a hash or a pound sign -- in the first column of the offending line, with something like

,s;/dev/sd1i /mnt/usb;#;g

Or, you could correct the line per the fstab(5) man page.*

You could also manually mount the rest of your filesystems in /etc/fstab, including the all-important /usr which contains the rest of the built-in editors in /usr/bin, then export a $TERM environment variable, and use an editor you are more comfortable with such as vi(1) or mg(1).

--

OpenBSD will create a virtual disklabel when a disk drive has MBR partitions but no OpenBSD disklabel on the drive. Recognized foreign filesystems in the MBR partition table will be assigned disklabel partitions beginning with "i". Assuming the drive will be assigned to device sd1 when inserted, the fstab entry for a FAT formatted drive drive should look something like this:

/dev/sd1i /mnt/usb msdos rw,noauto 0 0

Details of the syntax and the "noauto" option are discussed in the fstab(5) man page.

[betweendayandnight]

Originally Posted by jggimi

Hello, and welcome!

Thanks

Originally Posted by jggimi

You can still use ed(1), just put a "#" -- called a hash or a pound sign -- in the first column of the offending line, with something like

,s;/dev/sd1i /mnt/usb;#;g

The offending line happens to be line 11. Do I need to amend your command to:

11,s;/dev/sd1i /mnt/usb;#;g

or

11,s,11;/dev/sd1i /mnt/usb;#;g

Originally Posted by jggimi

then export a $TERM environment variable, and use an editor you are more comfortable with such as vi(1) or mg(1).

Is the following the correct command to export a $TERM environment variable?

export TERM=vt220

Originally Posted by jggimi

OpenBSD will create a virtual disklabel when a disk drive has MBR partitions but no OpenBSD disklabel on the drive. Recognized foreign filesystems in the MBR partition table will be assigned disklabel partitions beginning with "i". Assuming the drive will be assigned to device sd1 when inserted, the fstab entry for a FAT formatted drive drive should look something like this:

/dev/sd1i /mnt/usb msdos rw,noauto 0 0

Details of the syntax and the "noauto" option are discussed in the fstab(5) man page.

Thanks for the above info.

[jggimi]

Originally Posted by betweendayandnight

Thanks

The offending line happens to be line 11. Do I need to amend your command...

No, the leading ",s" combined with the trailing "g" will make the change globally, for every line that matches.

You can add or remove line breaks in these commands by referring to new lines escaped with a backslash. But it takes some practice. I do it now and again, but sometimes confuse myself. For example, to break every "keyboard" in a file with a line break between "key" and "board," one would type:

,s/keyboard/key\
board/g

Is the following the correct command to export a $TERM environment variable?

export TERM=vt220

Yes.

[betweendayandnight]

Originally Posted by jggimi

But it takes some practice. I do it now and again, but sometimes confuse myself. For example, to break every "keyboard" in a file with a line break between "key" and "board," one would type:

,s/keyboard/key\
board/g

Yes.

I agree with you. It's quite a steep learning curve for me to learn how to use ed

I managed to remove the offending line by first mounting the relevant partitions using the 16-alphanumeric-string UUIDs to / , /usr and /var

Secondly I

export TERM=vt220

Thirdly I

nano /etc/fstab

removed the offending line and rebooted.

[jggimi]

Excellent! Glad you got things repaired.