shell补-运算-数字运算

shell补-运算-数字运算

RANDOM

[root@localhost sub_str]# man bash  ###/RANDOM
.........
              RANDOM Each  time  this  parameter  is referenced, a random integer between 0 and 32767 is generated.  The sequence of random numbers may be
 initialized by assigning a value to RANDOM.  If RANDOM is
              unset, it loses its special properties, even if it is subsequently reset.
[root@localhost sub_str]# echo $RANDOM
5747
[root@localhost sub_str]# echo $RANDOM
778

bc的进制转换

##11转换为16进制。  16进制10就是A了注意
[root@localhost ~]# echo "obase=16;11"|bc
B
[root@localhost ~]# 

awk 'BEGIN{}' 在脚本进行统计计算

[root@localhost ~]# awk 'BEGIN{print 1+2}'
3
[root@localhost ~]# var1=1;var2=2
[root@localhost ~]# echo `expr $var1 + $var2 `
3
[root@localhost ~]# awk -vv=var1 -vy=var2 'BEGIN{print v+y}'
0
[root@localhost ~]# awk -v v=$var1 -v y=$var2 'BEGIN{print v+y}'  ###-v给变量传入值可以不要空格写成-vv=$var1 -vy=$var2
3
[root@localhost ~]# 
###########################
[root@localhost sub_str]# cat calculationtestawk.sh 
#!/bin/bash
#
#
a=${1}
b=${2}   ####多用变量，程序代码就不用经常调整。
echo `awk -v x=$a -vy=$b 'BEGIN{print x+y }'`
[root@localhost sub_str]# 

[root@localhost sub_str]# sh calculationtestawk.sh  1 3
4
[root@localhost sub_str]# 

expr 还能检查变量是否为数字