Systemy operacyjne - lab. 12
====================================================

1- powtorka

if [ $? -eq 0 ]
if [ $# -le 2 ]  less than two args
if [ "$1" = "tekst" ]  "$1" to avoid error if $1 not defined 
if [ -f "$1" -a -r "$1" ]  "$1" to avoid error if $1 not defined 

zmienne specjalne
 n  arg
 0  nazwa skryptu
 #  liczba args
 @  lista args "$1" .. "$n"
 *  lista args "$1 .. $n"
 ?  last stat
 $  PID this shell
 !  PID last proc in backg


2- petle

for f in *.txt
do
 mv $f $f.TXT
done

`seq 3 7`

while [ -n "$1" ]
do 
 echo "$1"
 shift
done

true

while ! ping -c 1 sirius > /dev/null 2>&1     -c stops after 1 send
do 
 sleep 20
done
echo "siec OK" | mail ..

break     ends loop
continue  przejscie do kolejnej iteracji


3- case

case $x in
 v) .. ;;
 v1|v2) .. ;;
esac

case $x in
 [tT]*) .. ;;
 *) .. ;;
esac


4- inne

read

while read l
do 
 echo $l
done < plik

cat plik |    dwa procesy => l not seen outside loop
while read l
do 
 echo $l
done

grep .. | head .. |
while


5- functions

procesy () 
{
 local x=1
 ps -u $1
}
procesy user

unset proc


6- lista args

lista.txt: 
a1
a2
c2

grep ^a lista.txt | xargs -t chmod go-x    -t echoes executed command (option)
chmod go-x a1 a2

grep ^a lista.txt | xargs -n 1 -t chmod go-x
chmod go-x a1
chmod go-x a2

(option -n specifies max number of args)

jak wprowadzic args w srodku ? see below

sh -c 'echo $2 $1' skrypt a b     -c wykonanie komend podanych w linii
grep ^a lista.txt | xargs sh -c 'cp $* /tmp' skrypt
cp a1 a2 /tmp