10. VietHung soft group - viethung_group@email.com
#!/bin/sh
#Vi du 7b
if [ -f $dirname/$filename ]
then
echo "Tep [$filename] da ton tai."
elif [ -d $dirname ]
then
echo "Duong dan [$dirname] da ton tai."
else
echo "Ca duong dan [$dirname] va tep [$filename] khong ton
tai."
fi
Trong vÝ dô trªn, f lµ cê kiÓm tra sù tån t¹i cña mét tÖp, d lµ cê ®Ó kiÓm tra sù tån t¹i mét th−
môc.
VÝ dô 8: CÊu tróc if phøc t¹p. Trong vÝ dô nµy b¹n sÏ hiÓu c¸ch sö dông ®iÒu kiÖn kÐp; &&
(vµ), || (hoÆc).
#!/bin/sh
#Vi du 8a
echo “Nhap so a: ”
read a
echo “Nhap so b: ”
read b
echo “Nhap so c: ”
read c
if [ $a –lt $c ] && [ $b –lt $c ] #xem c cã lín nhÊt kh«ng
then
echo “so c lµ so lon nhat.”
fi
Trong vÝ dô trªn, && (vµ) lµ dÊu kiÓm tra kÐp ®Ó kÕt hîp hai ®iÒu kiÖn. Ta cã thÓ hiÓu ®iÒu
kiÖn sau if nh− sau: “NÕu a nhá h¬n c vµ b nhá h¬n c th× ...” Ngoµi ra cßn cã || (... hoÆc ...).
#!/bin/sh
#Vi du 8b
if [ -f $dir/$file ] || [ -f $dir/$newfile ]
then
echo "Hoac tep [$file] "
echo "hoac tep moi [$newfile] da ton tai"
11. VietHung soft group - viethung_group@email.com
elif [ -d $dir ]
then
echo "Duong dan [$dir] da ton tai"
else
echo "Ca duong dan [$dir], tep [$file va tep moi $newfile]
deu khong ton tai"
fi
6.5 CÊu tróc rÏ nh¸nh nhiÒu tr−êng hîp: case
CÊu tróc case cã thÓ ®−îc hiÓu qua tËp c¸c tõ khãa sau:
case <biÕn>
in
biÕn-1)
<lÖnh>
biÕn-2)
<lÖnh>
biÕn-3)
<lÖnh>
...
*) #cßn l¹i
exit
esac
VÝ dô 9: VÝ dô vÒ case ®èi víi tham sè ®Çu vµo cña mét tÖp ch−¬ng tr×nh.
#!/bin/sh
#Vi du 9
size=0
page=200
option = “”
while [ "$1" != "" ]
do
case $1
in
-?) echo “Su dung cac tham so –l,-p,-s.”
exit;;
-l) line = 50
page = 500
option = “$option page[$page] line[$line] “
shift;;
-p) line = 40