字符串測試
==:表示測試兩個字符串是否相等,相等爲真,否則爲假
!=:表示測試兩字符串是否不等
>:字符串比較大小
<:字符串比較大小
單目運算
-n string:測試字符串是否爲空,空爲真,否則爲假
-z string:測試指定字符串是否不爲空,空爲假,否則爲真
實例
1、寫一腳本,通過參數傳遞用戶名,判斷用戶名是否和基本組名一致,如一致顯示ok,否則not same;
[root@station01 ~]# cat test14.sh #!/bin/bash # if ! id $1 &>/dev/null;then echo "No such user." exit 12 fi if [ $1 == `id -n -g $1` ];then echo "Ok" else echo "Not same." fi
2、寫一個腳本,通過參數傳遞,判斷輸入的如是q,Q,quit,Quit或QUIT退出腳本,否則顯示參數
[root@station01 ~]# cat test15.sh #!/bin/bash # if [ $# -lt 1 ];then echo "Argument is less than 1." exit 1 fi # if [ $1 = 'q' ];then echo "Quiting...." exit 2 elif [ $1 = 'Q' ];then echo "Quiting...." exit 3 elif [ $1 = 'quit' ];then echo "Quiting...." exit 4 elif [ $1 = 'Quit' ];then echo "Quiting...." exit 5 elif [ $1 = 'QUIT' ];then echo "Quiting...." exit 6 else echo $1 fi
3、bc命令的學習
1)方法1
[root@station01 ~]# echo "scale=2;33/12;" |bc 2.75
2)方法2
[root@station01 ~]# bc <<<"scale=2;33/12;" 2.75
4、傳遞三個參數,第一個爲整數,第二個爲算術運算符,第三個爲整數,將計算結果顯示出來,並保留兩位精度
[root@station01 ~]# cat test16.sh #!/bin/bash # if [ $# -lt 3 ];then echo "Argument:$0 ARG1 ARG2 ARG3" exit 2 fi echo "scale=2;$1$2$3;" | bc