shell 字符串的截取拼接

c=$a$b

c=$a"xyz"$b

c=$a$b.txt

ip=`cat /etc/yunhai.ini | grep cloud | cut -d "=" -f2 | cut -d "/" -f1`

http="http://"$ip":80/"



1.expr substr “$a” 1 8
2.echo $a|awk ‘{print substr(,1,8)}’
3.echo $a|cut -c1-8

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