Commands using mount

This is just a proof of concept: A FILE WHICH CAN AUTOMOUNT ITSELF through a SIMPLY ENCODED script. It takes advantage of the OFFSET option of mount, and uses it as a password (see that 9191? just change it to something similar, around 9k). It works fine, mounts, gets modified, updated, and can be moved by just copying it.

USAGE: SEE SAMPLE OUTPUT

The file is composed of three parts:

a) The legible script (about 242 bytes)

b) A random text fill to reach the OFFSET size (equals PASSWORD minus 242)

c) The actual filesystem

Logically, (a)+(b) = PASSWORD, that means OFFSET, and mount uses that option.

PLEASE NOTE: THIS IS NOT AN ENCRYPTED FILESYSTEM. To improve it, it can be mounted with a better encryption script and used with encfs or cryptfs. The idea was just to test the concept... with one line :)

It applies the original idea of http://www.commandlinefu.com/commands/view/7382/command-for-john-cons for encrypting the file.

The embedded bash script can be grown, of course, and the offset recalculation goes fine. I have my own version with bash --init-file to startup a bashrc with a well-defined environment, aliases, variables.

`mount -o remount` doesn't pick up new NFS options (eg. timeo, soft, retrans, etc) so you need to do a full mount/remount cycle. This one-liner makes it quick and easy :) Update your fstab with the new options, then run it.

Replace IP address with yours IP.

This is a handy command to put into ~/.bash_logout to automatically un-mount windows shares whenever the user logs out. If you use this on as a non-root account then you'll need to append sudo before umount and the user will need to have the appropriate sudoer rights to run the /bin/umount command.

Mounts a disk-image of a hdd with partitions

Just the commands for the lvreduce I keep forgetting.

Clone a root partition. The reason for double-mounting the root device is to avoid any filesystem overlay issues. This is particularly important for /dev.

Also, note the importance of the trailing slashes on the paths when using rsync (search the man page for "slash" for more details). rsync and bash add several subtle nuances to path handling; using trailing slashes will effectively mean "clone this directory", even when run multiple times. For example: run once to get an initial copy, and then run again in single user mode just before rebooting into the new disk.

Using file globs (which miss dot-files) or leaving off the trailing slash with rsync (which will create /mnt/target/root) are traps that are easy to fall into.

Assuming we have a disk image, created by dd if=/dev/sda of=image.dd we can check the image's partition layout with fdisk -ul image.dd, then substitute "x" with starting sector of the partition we want to mount. This example assumes that the disk uses 512Byte sectors

after that, you can launch bash script in your usb drive in FAT32.

Necessary for fsck for example.

The remount functionality follows the standard way how the mount command works with options from fstab. It means the mount command doesn't read fstab (or mtab) only when a device and dir are fully specified. After this call all old mount options are replaced and arbitrary stuff from fstab is ignored, except the loop= option which is internally generated and maintained by the mount command.

It does not change device or mount point.

(FreeBSD)

Once you've made the snapshot you can resume any stopped services and then back up the file system (using the snapshot) without having to worry about changed files.

When finished, the snapshot can be removed :

umount /mnt

mdconfig -d -u 1

rm /var/.snap/snap_var_`date "+%Y-%m-%d"`

if you use disk-based swap then it can defeat the purpose of this function.

Based on the execute with timeout command in this site.

A more complex script:

#!/bin/sh

# This script will check the avaliability of a list of NFS mount point,

# forcing a remount of those that do not respond in 5 seconds.

#

# It basically does this:

# NFSPATH=/mountpoint TIMEOUT=5; perl -e "alarm $TIMEOUT; exec @ARGV" "test -d $NFSPATH" || (umount -fl $NFSPATH; mount $NFSPATH)

#

TIMEOUT=5

SCRIPT_NAME=$(basename $0)

for i in $@; do

echo "Checking $i..."

if ! perl -e "alarm $TIMEOUT; exec @ARGV" "test -d $i" > /dev/null 2>&1; then

echo "$SCRIPT_NAME: $i is failing with retcode $?."1>&2

echo "$SCRIPT_NAME: Submmiting umount -fl $i" 1>&2

umount -fl $i;

echo "$SCRIPT_NAME: Submmiting mount $i" 1>&2

mount $i;

fi

done

Based on the execute with timeout command in this site.

A more complex script:

#!/bin/sh

# This script will check the avaliability of a list of NFS mount point,

# forcing a remount of those that do not respond in 5 seconds.

#

# It basically does this:

# NFSPATH=/mountpoint TIMEOUT=5; perl -e "alarm $TIMEOUT; exec @ARGV" "test -d $NFSPATH" || (umount -fl $NFSPATH; mount $NFSPATH)

#

TIMEOUT=5

SCRIPT_NAME=$(basename $0)

for i in $@; do

echo "Checking $i..."

if ! perl -e "alarm $TIMEOUT; exec @ARGV" "test -d $i" > /dev/null 2>&1; then

echo "$SCRIPT_NAME: $i is failing with retcode $?."1>&2

echo "$SCRIPT_NAME: Submmiting umount -fl $i" 1>&2

umount -fl $i;

echo "$SCRIPT_NAME: Submmiting mount $i" 1>&2

mount $i;

fi

done

mounts an ISO file to a directory on the target file system

-t option tells the system to look for a msdos filesystem

The /dev/fd0 is your floppy drive ( This may be different for you check /dev folder to confirm)

/mnt/floppy is the point where you want to mount the device to

Assuming we have a disk image, ie. created by

we can check the image's partition layout with

then, we substitute "x" with starting sector of the partition we want to mount. This example assumes that the disk uses 512 B sectors