http://www.regentsprep.org/Regents/phys ... icCode=03b

Faraday's Law


Ohm's Law


Battery-Resistor Circuit


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---

#!/bin/bash

# program: postfix log checker
# version: 1.2
# purpose: to check logs for mail transport
# usage: $0 from email@domain
#        $0 to email@domain

argc=$#       # argument count
argv[0]=$0    # argv[0] is a prog name

TEMP1=/tmp/$$.temp1
TEMP2=/tmp/$$.temp2
TEMP3=/tmp/$$.temp3

> $TEMP1
> $TEMP2
> $TEMP3

trap "rm -f $TEMP1 $TEMP2 $TEMP3; echo; echo 'program stopped by user'; exit" INT TERM

[ ! $1 ] && echo "please specify from or to, ie: from tomas" && exit
[ ! $2 ] && echo "please specify recipient email address, or a part of address" && exit

for foo in $( seq $argc )
do
   eval "argv[${foo}]=\$${foo}"
done

[ $1 == "from" ] && SEARCH=" from="
[ $1 == "to" ] && SEARCH=" to="

email=${argv[2]}

echo "------------------------------------------------"
echo "search: ($SEARCH)*${email}*"
echo "------------------------------------------------"

for logfile in $( ls -1 /var/log/maillog* )
do
   echo "parsing logfile ... $logfile"
   if [ $( echo $logfile | grep -i "*gz$" ) ]; then
      zcat $logfile | grep -i -E "${SEARCH}.${email}|${SEARCH}${email}" >> $TEMP1
   else
      cat $logfile | grep -i -E "${SEARCH}.${email}|${SEARCH}${email}" >> $TEMP1
   fi
done

cat $TEMP1 | sed -e "s/  / /g" | cut -d" " -f 6 | sed -e "s/://g" | sort | uniq \
   >> $TEMP2

EVENTS=$( cat $TEMP2 | wc -l )

echo "we have found $EVENTS records in our logs"
echo "compacting results"
echo "------------------------------------------------"

> $TEMP3
for event in $( cat $TEMP2 )
do
   > $TEMP1
   echo -n " $event"
   for logfile in $( ls -1 /var/log/maillog* )
   do
      if [ $( echo $logfile | grep -i "*gz$" ) ]; then
         zcat $logfile | grep -i $event | tr '\n' ' ' >> $TEMP1
      else
         cat $logfile | grep -i $event | tr '\n' ' ' >> $TEMP1
      fi
      echo -n "."
   done

   # here we have in $TEMP1 all the log events related to mail message"
   # we  have it as a single long line
   # first, check for sender and recipient
   sender=""; orig_recipient=""; recipient=""; status=""; datetime=""; timestamp=""

   #cat $TEMP1

   datetime=$( cat $TEMP1 | sed -e "s/  / /g" | cut -d" " -f1,2,3 ) > /dev/null
   timestamp=$( date -d "$datetime" "+%s" )

   REGULAR="s/.* \(from=[^ ,]*\).*/\1/p"
   sender=$( cat $TEMP1 | sed -n "$REGULAR" ) > /dev/null

   REGULAR="s/.* \(to=[^ ,]*\).*/\1/p"
   recipient=$( cat $TEMP1 | sed -n "$REGULAR" ) > /dev/null

   REGULAR="s/.* \(orig_to=[^ ,]*\).*/\1/p"
   orig_recipient=$( cat $TEMP1 | sed -n "$REGULAR" ) > /dev/null

   REGULAR="s/.* \(status=[^ ]*\).*/\1/p"
   status=$( cat $TEMP1 | sed -n "$REGULAR" ) > /dev/null

   if [ $orig_recipient ]; then
      echo "$timestamp, $event, $datetime, $sender, $orig_recipient (yet forwarded!), $status" >> $TEMP3
   else
      echo "$timestamp, $event, $datetime, $sender, $recipient, $status" >> $TEMP3
   fi
done

echo
echo "------------------------------------------------"
echo "generating list, please press  space to continue"
echo "running more                                    "
echo "q to quit                                       "
echo "------------------------------------------------"
echo
sleep 3

sort -n  --key=1,9 $TEMP3 | more

rm $TEMP1
rm $TEMP2
rm $TEMP3

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---

A free series of textbooks on the subjects of electricity and electronics
Copyright (C) 2000-2012, Tony R. Kuphaldt
http://openbookproject.net/electricCircuits/

Units
http://www.knowledgedoor.com/2/units_an ... fixes.html

Circuit Simulation DC only, Java
http://phet.colorado.edu/en/simulation/ ... ion-kit-dc

Calculating an resistor value
http://www.kpsec.freeuk.com/components/led.htm

Kirhoff's Law explained
http://electron9.phys.utk.edu/phys136d/ ... chhoff.htm
http://www.regentsprep.org/Regents/phys ... efault.htm
http://www.physics.uoguelph.ca/applets/ ... index.html


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---

signály jsou softwarová přerušení běhu procesu a slouží ke komunikaci mezi procesy nebo v rámci procesu.

přehled signálů, jak je popisuje standard POSIX.1-1990

------------------------------------------------------
Signal     Value     Action   Comment
------------------------------------------------------
HUP           1       Term    Hangup detected on controlling terminal
                              or death of controlling process
INT           2       Term    Interrupt from keyboard
QUIT          3       Core    Quit from keyboard
KILL          4       Core    Illegal Instruction
ABRT          6       Core    Abort signal from abort(3)
FPE           8       Core    Floating point exception
KILL          9       Term    Kill signal
SEGV         11       Core    Invalid memory reference
PIPE         13       Term    Broken pipe: write to pipe with no readers
ALRM         14       Term    Timer signal from alarm(2)
TERM         15       Term    Termination signal
                              TERM is a default signal sent by kill(1) command

------------------------------------------------------
Signal     Value     Action   Comment
------------------------------------------------------
USR1      30,10,16    Term    User-defined signal 1
USR2      31,12,17    Term    User-defined signal 2
CHLD      20,17,18    Ign     Child stopped or terminated
CONT      19,18,25    Cont    Continue if stopped
STOP      17,19,23    Stop    Stop process
TSTP      18,20,24    Stop    Stop typed at tty
TTIN      21,21,26    Stop    tty input for background process
TTOU      22,22,27    Stop    tty output for background process

handler zajišťuje mapování signálu na obslužný kód. obsluhu signálů KILL a STOP přebírá vždy operační systém. v jiných případech je možno určit, zda signál je ignorován (SIG_IGN), zpracován v operačním systému definovaným obslužným programovým kódem - default (SIG_DFL), nebo obsloužen pro proces specifickým programovým kódem.

http://www.enderunix.org/docs/signals.pdf


Catching signal in BASH, example 1

#!/bin/bash
trap "echo 'ahoj ahoj, jsem signal USR1'" USR1
echo $$
while true
do
   sleep 1
done

Catching signal in BASH, example 2

if [ ! -e $lockfile ]; then
   trap "rm -f $lockfile; exit" INT TERM EXIT
   touch $lockfile
   critical-section
   rm $lockfile
   trap - INT TERM EXIT
else
   echo "critical-section is already running"
fi

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---

http://www.gme.cz/keramicke-kondenzator ... -p120-053/

0.01u je 10nF, 0.022u je 22n

www.mouser.com

http://cz.mouser.com/Home.aspx

skripta
http://elektross.gjn.cz/skripta/

Books
http://www.magsmoke.com/TH-101-Sheboygan-566-VCO.asp


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---

http://www.youtube.com/watch?feature=en ... D-cNc6StVI

http://brightstorm.com/science/

http://www.youtube.com/watch?v=VrNLVQZ-CZo

simple vco
http://www.sentex.ca/~mec1995/gadgets/pll/pll.html

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---

http://www.paia.com/bckit1/simpletheory.asp

Building Synthetizers
http://www.magsmoke.com/thomas_henry_books.asp

Stavebnice Voltik
http://e-shop.voltik.cz/stavebnice-volt ... 50047.html

Rozcestnik - DIY Effect Projects
http://www.squidoo.com/buildASynth

Electronic circuit simulator.
http://www.falstad.com/circuit/

Electronic circuit designer.
http://www.tina.com

Some other electronic cirtuit designers
http://www.electronics-lab.com/download ... index.html

A pad sound with Voyager
http://www.moogmusic.com/forum/viewtopic.php?t=8173

Roland Juno service manual
http://servicerepairmanuals.net/others/ ... ual-notes/

Roland Juno 80 schematics
http://www.fantasyjackpalance.com/fjp/s ... juno6.html

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---

The aliases(5) file is used only for local(8) deliveries. When
mail is forwarded, you may be able to get by with the virtual(5)
alias map.

If the transport_maps or smart relay option is used and the server is a mail forwarder for a domain which he itself is a member of, then the root mail is also forwarded to the next hop as is defined in transport_maps or smart relay.

Iif the root mail should be sent to other address which has mailbox elsewhere than on a next hop, then the virtual must be used.

cat /etc/postfix/virtual

root@somedomain.cz             log@fsit.cz
root@somedomain.cz             log@fsit.cz
localhost.somedomain.cz        log@fsit.cz
root@localhost                 log@fsit.cz

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---

snippets:

cat /sys/class/fc_host/host*/port_name | speed

multipath -v2 -d

http://www.softpanorama.org/Commercial_ ... ager.shtml

http://www.datadisk.co.uk/main/lvm.htm

----------


lvscan <- logical volume scan
lvremove vol1 vol2 <- remove logical vomumes
vgscan <- volume group scan
vgremove raid5 <- remove volume group
pvscan <- physical volume scan
pvremove /dev/cciss/c0d1 <- wipe the device rom lvm2


------------------------------------------------------
physical device to (pvcreate, pvremove, pvscan)
------------------------------------------------------
volume group of physical devices (vgcreate, vgremove, vgscan)
------------------------------------------------------
logical volume (lvcreate, lvremove, lvscan)
------------------------------------------------------

------------------------------------------------------
lvmdiskscan - reads all the partitions

---
pvs -vvvvv
vgs
lvs



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---

Marking a directory sticky (t) directory users can have read and/or write permissions for that directory, but they can only remove or rename files that they own.
Marking a directory setgid (g+s) will make new files inherit the group ownership of the directory

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---

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