Linux指令篇:字串处理--expr

名称：expr

### 字串长度

shell>> expr length "this is a test"

14

### 数字商数

shell>> expr 14 % 9

5

### 从位置处抓取字串

shell>> expr substr "this is a test" 3 5

is is

### 数字串 only the first character

shell>> expr index "testforthegame" e

2

### 字串真实重现

shell>> expr quote thisisatestformela

thisisatestformela