Commands

putty -l bjorklun -pw password -L 19242:192.168.0.42:3389 blt.homeip.net

dd if=/dev/hda of=/dev/fd0 bs=512 count=1

bash:
Get a list from 01 to 99.
for ((a=100;a <= 199 ;a++)); do echo "$a"; done | cut -b2-3

install src.rpm
rpmbuild --rebuild alien-6.51-1.src.rpm
rpm -i /usr/src/redhat/RPMS/x86_64/alien-6.51-1.rpm

List contents of rpm.
rpm -qlp myfile.rpm

Extract contents of rpm.
rpm2cpio *.rpm | cpio -i --make-directories

Clean file from comments and blank lines.
sed '/ *#/d; /^ *$/d'

Update release area Windows.
servicepack.exe -s:z:\w2k3

Syncronize folders.
rsync --delete -az -e ssh acrobatreader acdse office2003 java nortonantivirus bjorklun@semco.homeip.net:/install/program/windows/

crontab.
* * * * *  command to be executed
- - - - -
| | | | |
| | | | +----- day of week (0 - 6) (Sunday=0)
| | | +------- month (1 - 12)
| | +--------- day of month (1 - 31)
| +----------- hour (0 - 23)
+------------- min (0 - 59)
0 Sunday
1 Monday
2 Tuesday
3 Wednesday
4 Thursday
5 Friday
6 Saturday

Automated login on a user basis.
ssh-keygen -t dsa                    Generate personal ssh keys.
cat id_dsa.pub >> authorized_keys2   Copy your personal ssh key to all machines.
chmod 644 ~/.ssh/authorized_keys2    Verify correct access on files.

-forward traffic.
service x11
{
        disable = no
        socket_type = stream
        protocol = tcp
        wait = no
        user = root
        server = /usr/bin/nc
        server_args = 172.28.37.152 6000
}

reboot

Hard reboot mean that shutdown scripts will not run and machine reboot immediately without syncing hard disk drives, shutdown applications etc.
echo 1 > /proc/sys/kernel/sysrq
echo b > /proc/sysrq-trigger

This commands enable sysrq and after this call fast reboot. If you want to force shutdown machine try this.
Force shutdown

echo 1 > /proc/sys/kernel/sysrq 
echo o > /proc/sysrq-trigger