CentOS 7 Shell指令碼程式設計第八講 Bash Shell 簡單數值運算
阿新 • • 發佈：2019-04-01
Bash Shell 可以進行一些簡單數值運算。例如簡單整數+-*/和整數指數運算。
#注意對比輸出結果 [root@promote ~]# echo $((1+11111111111111111111111111111111111111111111111111111111)) -3835065282685275704 [root@promote ~]# echo $((1+111111111111111)) 111111111111112 [root@promote ~]# echo $((1+1111111111111111)) 1111111111111112 [root@promote ~]# echo $((1+11111111111111111)) 11111111111111112 [root@promote ~]# echo $((1+111111111111111111)) 111111111111111112 [root@promote ~]# echo $((1+1111111111111111111)) 1111111111111111112 [root@promote ~]# echo $((1+11111111111111111111)) -7335632962598440504 [root@promote ~]# echo $((1+111111111111111111111)) 430646668853801416 [root@promote ~]# echo $((2**3)) 8 [root@promote ~]# echo $((1-7777777777777777)) -7777777777777776 [root@promote ~]# echo $(((50*70)/2)) 1750 [root@promote ~]# a=8 [root@promote ~]# echo $((a=a+1)) 9 [root@promote ~]# echo $((a/3)) 3 [root@promote ~]# echo $((a**3)) 729 [root@promote ~]# echo $a 9 [root@promote ~]# echo $((8==7)) 0 [root@promote ~]# echo $((8>7)) 1 [root@promote ~]# echo $((8<7)) 0 [root@promote ~]# echo $((8<=7)) 0 [root@promote ~]# echo $((8>=7)) 1 [root@promote ~]# echo $((1/2)) 0 [root@promote ~]# echo $((1/3)) 0
複雜運算可以嘗試使用命令列直譯器bc。
#
[root@promote ~]# yum install bclet 命令基本等同於(())。複雜運算推薦使用awk。
[root@promote ~]# echo "302 125" | awk '{print ($1-2)/$2}'
2.4
[root@promote ~]# echo "302 100" | awk '{print ($1-2)/$2}'
3
[root@promote ~]# echo "302 100" | awk '{print $1+$2}'
402
[root@promote ~]# echo "302 100" | awk '{print $1-$2}'
202
[root@promote ~]# echo "302 100" | awk '{print $1*$2}'
30200
[root@promote ~]# echo "302 100" | awk '{print $1/$2}'
3.02
[root@promote ~]# echo "302 100" | awk '{print $1**$2}'
100159995352569794157337122264449633359340789387852910740121009667012307693563577085101962837571466472836569051169628003691266451752717050890980506496841970147265639778330507058712176709486840856688987753267362751648557469738863812361843311653158912
[root@promote ~]#