[CLUE-Tech] file check other than at boot

[Nate Duehr]

James LaRue wrote:

> A newbie question. If a Linux box does lock up, and is shut down 
> uncleanly, a reboot offers to do a file check. What is the command to 
> perform the same file integrity check, as root, from a terminal window?


The other answers about unmounting the filesystem (something you can't 
do if your entire machine is one big "/" partition and you're booted 
from that partition) are correct regarding fsck.

Also keep in mind that it's not a "file integrity" check, it's a 
"filesystem integrity" check.  In very extreme cases (usually when a 
disk is sick and not writing things where it should anyway), fsck while 
repairing the underlying filesystem can destroy "files" -- i.e. your 
precious data. 

You sometimes end up with recovered bits and pieces in your lost+found 
directory for each mount point (with no filenames... lovely to sort 
through) or you may just find things are gone forever. 

In other words, fsck is a great tool, but it can't do your system 
backups for you.  ;-)

Nothing in the world beats the feeling that you have backups AND you've 
restored them somewhere else and they worked during the test.  :-) :-) :-) 

If the data is worth money (work/production machines) it's inexcusable 
for a professional admin not to have a backup, and nowadays you probably 
want an "online" backup on another disk platter somewhere, an off-line 
backup on some sort of removable media, and an off-site backup, 
somewhere completely away from the building you're in -- in a safe place.

If it's at-home-I-don't-really-care-about-it data, the level of risk of 
running without backups is up to the time, personality type, and sanity 
level (or lack thereof when the drive fails -- remember ALL drives 
eventually fail...) of the admin.  (GRIN)  Heh...

Nate Duehr, nate at natetech.com