break out of e2fsck on boot

Question

Is it possible to somehow break out of e2fsck on boot?

My system runs e2fsck every 30 days, which is fine by me and I want it to stay that way. But sometimes when I turn on the computer and 30 days have passed, I still want it to boot fast. For instance when I have to give a presentation off a laptop - imagine telling 50 people "we just have to wait for 10 minutes... no, I can't avoid it... yes, this is Linux, why are you asking?" :)

If I press Ctrl+C it stops the check and continues boot sequence, but the system is unusable because root filesystem is mounted read-only. And after I reboot the check starts again.

I have searched the Internet for the answer and there are many similar questions, but I could find no solution. Anyone know of a solution?

Note: I am looking for a solution that would not disable fsck and that would not require any action before rebooting the computer - I do not know in advance I will have to skip the check.

If it matters: Debian 6 (Squeeze).\

UPDATE: I learned that it is possible to break out of e2fsck with Esc key on Ubuntu. This is exactly what I am looking for - anyone know how to make this happen on Debian?

Answer 1

There are three easy ways to achieve what you're looking to do, depending on the situation.

1. When shutting down, use the command line shutdown binary and pass the -f switch, e.g. for a reboot: shutdown -rf now. You could also make a shortcut with this if you'd prefer. This will skip the fsck check on the next reboot only.
2. When the grub menu is displayed on boot hit 'e' to edit the current booting kernel, edit the vmlinuz line and append fastboot to the end. Like option 1, this skips the fsck check for that boot only.
3. If you really want to disable the check entirely (not recommended), you can edit the file /etc/fstab. Find the line with your root filesystem and at the end there will be two numbers, usually 1 2. Changing the last number (2 here) to 0 will prevent all automatic boot-time fsck checks from running on that volume.

Edit for #2: You could add a new entry to grub for fastboot, which may be more suited to your example case. This retains the normal fsck check while presenting a choice during boot.

Answer 2

While it does not directly address your question of how to abort a running fsck, if you know in advance that you will need a fast boot (such as if you are planning to give a presentation) then you can certainly run fsck manually at some earlier time. This will give you a new 30 days before the next automated file system check without touching any system configuration.

Answer 3

You can edit the startup script which calls fsck. So you could for example make it ask the console whether to do a fsck, with a timeout. The scripts are in /etc/init.d/checkroot.sh and /etc/init.d/checkfs.sh.

I notice that my copy has this code in it which you could re-enable:

# Disabled AC power check until fsck can be told to only check the
# file system if it is corrupt when running on battery. (bug #526398)
#       if which on_ac_power >/dev/null 2>&1 && [ "$rootcheck" = yes ]
#       then
#               on_ac_power >/dev/null 2>&1
#               if [ "$?" -eq 1 ]
#               then
#                       log_warning_msg "On battery power, so skipping file system check."
#                       rootcheck=no
#               fi
#       fi