Linux Learning essay-shell simple writing

Scripts are best placed in/usr/local/sbin.

the script executes the Sh-x script. Sh-x can view the execution process1 when using variables in a script, use the $ symbol: #!/bin/bash # #把命令赋值为变量, you need to use anti-quotes d= ' date + '%h:%m:%s ' echo "The script begin at $d" echo "Now we'll sleep 2 seconds" Sleep 2 d1= ' date + '%h:%m:%s ' echo "The script end at $d" 2 use mathematical operations in scripts to be enclosed in [] as follows #!/bin/bash a=1 b=2 # #数学运算用 [] surround it. sum=$[$a + $b] echo "$a + $b = $sum" 3 using the Read command with the console interactively in the script #!/bin/bash read-p "Please input a number:" X read-p "Please input a number:" Y sum=$[$x + $y] echo "The sum of the tow numbers is: $sum" preset variables in 4shell #!/bin/bash echo " $ $ $" 1 2 is a preset variable in the script a preset variable in a script is unlimited, and 0 means the script file book # SH option.sh 1 2 3The output of executing this command is as follows: 1 2 3 option.sh   logic judgment in 5shell if notice without else if the judgment statement after the IF is used (()) or the error will be #!/bin/bash read-p "Please input your score:" A if ((a<60)); Then echo "You didn ' t pass the exam." fi 5.1 with the Else instance code is as follows #!/bin/bash read-p "Please input your score:" A if ((a<60)); Then echo "You didn ' t pass the exam." Else echo "good! You passed the exam. " fi 5.2 with Else if (this is the argument in C) is represented in the shell as Elif #!/bin/bash read-p "Please input your score:" A if ((a<60)); Then echo "You didn ' t pass the exam." elif ((a>=60)) && ((a<85)); Then echo "good! You passed the exam. " Else echo "Very good! Your score is very heigh " fi 5.3case Logic judgment #!/bin/bash read-p "Input a number:" N a=$[$n%2]Case $a in 1) echo "The number is odd."     ;; 0) echo "The number is even."     ;; *) echo "It ' s not a number"     ;; Esac * indicates other values 6for CycleThe instance code is as follows: #!/bin/bashFor file in ' ls ';d o Echo $file Done 7while Cycle #!/bin/bash a=5 while [$a-ge 1]; Echo $a a=$[$a-1] Done          

Linux Learning essay-shell simple writing