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19990118: file system problems on Linux requiring manual fsck (cont.)

>From: David Travis <address@hidden>
>Organization: University of Wisconsin-Whitewater
>Keywords: 199901182209.PAA24587 Linux fsck single user


>Thanks for the reply.

>Unfortunately, I can't seem to get past the "fsck" command.  When I type
>"fsck" nothing happens.  I think I am in single user mode and am putting in
>the password for 'root' but am not getting a response.  How can I tell for
>sure if I am in 'root' and/or single user mode?  I don't get any list of
>"options" upon reboot as you imply above.

On Linux, you need to give 'fsck' a target file system.  Here is the
beginning of the 'fsck' man page on RedHat 5.2 Linux:

FSCK(8)                                                   FSCK(8)

       fsck - check and repair a Linux file system

       fsck  [  -AVRTNP  ]  [  -s  ] [ -t fstype ] [ fs-options ]
       filesys [ ... ]

       fsck is used to check and optionally repair a  Linux  file
       system.    filesys   is   either  the  device  name  (e.g.
       /dev/hda1, /dev/sdb2) or the mount point  (e.g.  /,  /usr,
       /home)  for  the  file system.  If this invocation of fsck
       has several filesystems on different physical disk  drives
       to  check,  then  fsck  will  try to run them in parallel.
       This reduces the total amount time it takes to  check  all
       of the filesystems, since fsck takes advantage of the par-
       allelism of multiple disk spindles.

       The exit code returned by fsck is the sum of the following
            0    - No errors
            1    - File system errors corrected
            2    - System should be rebooted
            4    - File system errors left uncorrected
            8    - Operational error
            16   - Usage or syntax error
            128  - Shared library error
       The  exit  code returned when all file systems are checked
       using the -A option is the bit-wise OR of the  exit  codes
       for each file system that is checked.

       In  actuality,  fsck is simply a front-end for the various
       file system checkers (fsck.fstype) available under  Linux.
       The  file system-specific checker is searched for in /sbin
       first, then in /etc/fs and /etc, and finally in the direc-
       tories  listed  in  the PATH environment variable.  Please
       see the file system-specific checker manual pages for fur-
       ther details.

       -A     Walk  through  the /etc/fstab file and try to check
              all file systems in one run.  This option is  typi-
              cally  used  from  the /etc/rc system initalization
              file, instead of multiple commands for  checking  a
              single file system.

       -R     When  checking  all  file systems with the -A flag,
              skip the root file system  (in  case  it's  already
              mounted read-write).

       -T     Don't show the title on startup.

       -N     Don't execute, just show what would be done.

       -P     When  the -A flag is set, check the root filesystem
              in parallel with the other  filesystems.   This  is
              not  the  safest thing in the world to do, since if
              the root filesystem is in  doubt  things  like  the
              e2fsck(8)  executable  might  be  corrupted!   This
              option is mainly provided for those  sysadmins  who
              don't want to repartition the root filesystem to be
              small and compact (which is really the right  solu-

       -s     Serialize  fsck operations.  This is a good idea if
              you checking multiple filesystems and the  checkers
              are  in an interactive mode.  (Note: e2fsck(8) runs
              in  an  interactive  mode  by  default.   To   make
              e2fsck(8)  run  in a non-interactive mode, you must
              either specify the -p or -a option, if you wish for
              errors  to  be  corrected  automatically, or the -n
              option if you do not.)

       -V     Produce verbose output, including all file  system-
              specific commands that are executed.

       -t fstype
              Specifies  the  type  of file system to be checked.
              When the -A flag  is  specified,  only  filesystems
              that  match  fstype are checked.  If fstype is pre-
              fixed with no then only filesystems whose type does
              not match fstype are checked.

              Normally, the filesystem type is deduced by search-
              ing for filesys in the /etc/fstab  file  and  using
              the  corresponding  entry.   If the type can not be
              deduced, fsck will use the type specified by the -t
              option  if  it  specifies a unique filesystem type.
              If this type is not  available,  then  the  default
              file system type (currently ext2) is used.

              Any  options  which  are not understood by fsck, or
              which follow the -- option are treated as file sys-
              tem-specific  options to be passed to the file sys-
              tem-specific checker.

       Currently, standardized file system-specific  options  are
       somewhat  in flux.  Although not guaranteed, the following
       options are supported by most file system checkers:

       -a     Automatically repair the file  system  without  any
              questions  (use  this  option  with caution).  Note
              that e2fsck(8) supports -a for  backwards  compati-
              bility  only.  This option is mapped to e2fsck's -p
              option which is safe to use, unlike the  -a  option
              that most file system checkers support.

       -r     Interactively  repair  the filesystem (ask for con-
              firmations).  Note: It is generally a bad  idea  to
              use this option if multiple fsck's are being run in
              parallel.  Also note that this is e2fsck's  default
              behavior;  it  supports  this  option for backwards
              compatibility reasons only.


We recommend that you first try:

fsck -A -r

This will go through the file systems listed in /etc/fstab and will ask
you if you want to make repairs when something is found to be bad.
Given that we don't know what is damaged, I would suggest that you
answer 'yes' when asked if you want to make a repair.

>Please forgive me since I'm just a novice at Linux.

No problem.

>By the way,  our machine crashed when we had a power outage over New Year's.
>Upon rebooting it came up once and then after a second reboot (and proper
>shutdown) we had this 'fsck' problem.   Probably unavoidable...but we are
>planning to buy a backup battery generator pack in case this happens again.

OK.  This sounds like the fix will be pretty simple.  If you run into
problems you can't figure out, then give Don or I a call:

Tom: 303-497-8642
Don: 303-497-8628

Tom Yoksas

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