CentOS详细安装之十七：Linux的简单shell脚本中进行计算（类型转换）
1 #!/bin/bash 2 # int-or-string.sh: 整型还是字符串? 3 4 a=2334 # 整型. 5 let "a += 1" 6 echo "a = $a " # a = 2335 7 echo # 还是整型. 8 9 10 b=${a/23/BB} # 将"23"替换成"BB". 11 # 这将把变量b从整型变为字符串. 12 echo "b = $b" # b = BB35 13 declare -i b # 即使使用declare命令也不会对此有任何帮助. 14 echo "b = $b" # b = BB35 15 16 let "b += 1" # BB35 + 1 = 17 echo "b = $b" # b = 1 18 echo 19 20 c=BB34 21 echo "c = $c" # c = BB34 22 d=${c/BB/23} # 将"BB"替换成"23". 23 # 这使得变量$d变为一个整形. 24 echo "d = $d" # d = 2334 25 let "d += 1" # 2334 + 1 = 26 echo "d = $d" # d = 2335 27 echo 28 29 # null变量会如何呢? 30 e="" 31 echo "e = $e" # e = 32 let "e += 1" # 算术操作允许一个null变量? 33 echo "e = $e" # e = 1 34 echo # null变量将被转换成一个整型变量. 35 36 # 如果没有声明变量会怎样? 37 echo "f = $f" # f = 38 let "f += 1" # 算术操作能通过么? 39 echo "f = $f" # f = 1 40 echo # 未声明的变量将转换成一个整型变量. 41 42 43 44 # 所以说Bash中的变量都是不区分类型的. 45 46 exit 0