Linux 常用命令速查

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expr 命令详情

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