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Shell-coding: ïðîãðàììèðóåì â *nix-êîíñîëè
SHuRuP
Êîãäà ñèäèøü â êîíñîëè (à âñå ìû ñ ýòèì ñòàëêèâàåìñÿ),
íåâîëüíî õî÷åòñÿ îïòèìèçèðîâàòü/óïðîñòèòü ðàáîòó â
íåé. Êàê ýòî ñäåëàòü Ìíîãèå ïîñîâåòóþò ó÷èòü Ñ/Ñ++,
íî çà÷åì íàïðÿãàòüñÿ áîëüøå, åñëè åñòü ñïîñîá ïðîùå
Ó âñåõ *nix-ñèñòåì (ñîâðåìåííûõ) îáÿçàòåëüíî åñòü íåñêîëüêî
êîìàíäíûõ èíòåðïðåòàòîðîâ, âîò ñàìûå èçâåñòíûå
èç íèõ:
Bourne Shell aka /bin/sh - èìåííî îí è áóäåò ðàññìàòðèâàòüñÿ
â ýòîé ñòàòüå (èíèöèàëèçàöèÿ - .profile);
Bourne-Again Shell aka /bin/bash - èäåíòè÷åí Bourne
Shell (.profile è .bashrc);
C Shell aka /bin/csh - èíòåðïðåòàòîð äëÿ C-ïðîãðàììåðîâ
(.login è .cshrc).
 û ï î ë í å í è å
ñêðèïòîâ íà sh
ðàâíîñèëüíî íàáèðàíèþ
âñåõ ýòèõ êîìàíä ñ êîíñîëè.
Âñå ïðîãðàììû äîëæíû íà÷èíàòüñÿ ñ: #!/bin/sh
Êîììåíòàðèè íà÷èíàþòñÿ ñ ïîìîùüþ ñèìâîëà '#'. Çíà-
÷åíèÿ ïåðåìåííûì çàäàþòñÿ òàê:
var1=value
var1 - ïåðåìåííàÿ, value - çíà÷åíèå ýòîé ïåðåìåííîé.
Äàëüøå ñëåäóåò èñïîëüçîâàòü äàííóþ ïåðåìåííóþ ñ
ñèìâîëîì '$' â íà÷àëå ($var1). Ñóùåñòâóþò òàêæå äðóãèå
âîçìîæíîñòè ïîëó÷åíèÿ ïåðåìåííîé:
${var1}text - îòäåëÿåò çíà÷åíèå $var1 îò ïîñëåäóþùåãî
òåêñòà (text);
${var1:=var2} - åñëè çíà÷åíèå $var1 íå îïðåäåëåíî, òî
åé ïðèñâàèâàåòñÿ çíà÷åíèå $var2;
${var1:-var2} - åñëè çíà÷åíèå $var1 íå îïðåäåëåíî, òî
âûâîäèòñÿ çíà÷åíèå $var2 ($var1 îñòàåòñÿ íå îïðåäåëåííûì).
#!/bin/sh
#script 1
var1=text1
var2=text2
echo ${var1}klm
#âûâåäåò text1klm
echo ${var1:=$var2}
#âûâåäåò text1
echo ${var4:=$var2}
#âûâåäåò text2
echo ${var4:-$var1}
#âûâåäåò text2
Íåêîòîðûå ïåðåìåííûå, èñïîëüçóåìûå sh:
$$ - pid òåêóùåãî shell'à;
$! - pid ïîñëåäíåãî ïðîöåññà â ôîíîâîì ðåæèìå;
$ - êîä âîçâðàòà ïîñëåäíåãî ïðîöåññà;
$x - ãäå x-÷èñëà: ïàðàìåòðû, ïåðåäàííûå ñêðèïòó ($0 -
ïîñëåäíèé çàïóùåííûé ñêðèïò).
#!/bin/sh
#script 2
echo "script filename: $0"
#âûâåäåò íàçâàíèå ôàéëà äàííîãî ñêðèïòà
echo "value1: $1"
#âûâåäåò ïåðâûé ïàðàìåòð, çàäàííûé ñêðèïòó
echo "value2: $2"
#âûâåäåò âòîðîé ïàðàìåòð, çàäàííûé ñêðèïòó
Ïàðàìåòðû ñêðèïòó çàäàþòñÿ òàê:
/home/shurup/script1 value1 value2 value3
value1, value2, value3 - ïàðàìåòðû äëÿ ñêðèïòà.
Shell-coding:
 Bourne Shell òàêæå âîçìîæíî ñîçäàíèå óñëîâèé:
if [ óñëîâèå ]
then äåéñòâèÿ ïðè âûïîëíåíèè óñëîâèÿ
else äåéñòâèÿ ïðè íåâûïîëíåíèè óñëîâèÿ
fi
#!/bin/sh
#script 3
if [ $1 == $2 ]
then echo "$1 ðàâíî $2"
else echo "$1 íå ðàâíî $2"
fi
Öèêëû â sh ñîçäàþòñÿ òàê:
while êîìàíäà1
do
äåéñòâèå1
done
Äåéñòâèå1 áóäåò èñïîëíÿòüñÿ äî êîíöà âûïîëíåíèÿ êîìàíäû1.
#!/bin/sh
#script 4
while :
do
echo test
done
 ñëó÷àå çàïóñêà ýòîãî ñêðèïòà êîìàíäà 'echo test' áóäåò
âûïîëíÿòüñÿ â áåñêîíå÷íîì öèêëå.
Äëÿ ñ÷èòûâàíèÿ èíôîðìàöèè â sh èñïîëüçóåòñÿ êîìàíäà
'read'.
#!/bin/sh
#script 5
cat ./sh_script5.txt | grep text1 |
while read text
do
if [ $text == "text1" ]
then echo "text1 áûë óñïåøíî
íàéäåí â ôàéëå sh_script5.txt"
else echo "text1 íå áûë íàéäåí
â ôàéëå sh_script5.txt"
fi
done
Ýòîò ñêðèïò íàäî çàïóñêàòü èç îäíîãî êàòàëîãà ñ ôàéëîì
sh_script5.txt. Ôàéë sh_script5.txt âûãëÿäèò ïðèìåðíî
òàê:
text7
text45
text1
text35
È íà ýòîò ôàéë äîëæíî áûòü ïðàâî ÷òåíèÿ (chmod +r
sh_script5.txt).
Òåïåðü òû çíàêîì ñ îñíîâàìè êîäèíãà â Bourne
Shell. Óñïåõîâ íà ýòîì ïîïðèùå!
P.S. Âñå ñêðèïòû ìîæíî ñêà÷àòü çäåñü:
http://nix.h1.ru/articles/shprog.zip
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