Shell Scripting Exercises

1. Calculate the sum of the 1~100 of the word:

Require the accumulation of numbers, you can use the loop to complete, the following code:

#!/bin/bashsum=0str= "" #for i in {1..100}for ((i=1; i<=100; ++i)) does str+= "${i}+" Let Sum+=idoneecho "${str%+}=${ Sum} "

To run the script:

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Another way to use recursion is to:

#!/bin/bashread num sum=0str= "" function Sum_fun () {num1=$1 if [${num1}-le 1];then//returns echo directly when the value is less than or equal to 1 $n Um1 return fi let--num1 tmp=$ (sum_fun $num 1)//recursive call let sum=$1+ $tmp echo ${sum}}sum=$ (Sum_fun $num ) echo "${sum}"

When you use the $ () command substitution, the commands inside the parentheses are executed, so a new process is created to execute the command, which means that the variables are valid within a process, so you need to be careful when you use them.

To run the program:

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2. Progress bar

To write a simulation progress bar using a shell script:

#!/bin/bashstr= "" Arr= ('-"\" | " '/')//define array to simulate cursor rotation for ((i=1; i<=100; ++i)) does let tmp=${i}%4 str+= "#" printf "[%-100s][${i}%%] ${arr[$tmp]} \ r" "${str}"//Only line will not sleep 0.1 doneprintf "\ n"

To run the program:

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3. Find the maximum, minimum, and average value of the data in a file with a precision of 2

The data value in the file is one row of data;

#!/bin/bashsum=0count=0while read line//++count//compute data count by rows [$count-eq 1] && min= $line && max= $line//Initialize the maximum minimum value so that it is equal to the first data let sum+= $line//calculated value and [$line-gt $max] && max= $line//If the data is greater than the maximum value, update max [$ Line-lt $min] && min= $line//If the data is less than the minimum value, update the minimum done<file//output redirect echo "Max: ${max}" echo "min: ${min}" printf "argv : "Echo" Base=10;scale=2;${sum}/${count} "| Bc

To run the program:

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4. To find the nth Fibonacci number

To find the nth Fibonacci number, you need to know the number N-1 and the N-2 Fibonacci numbers.

#!/bin/bash//uses three variables in turn, the highest efficiency read numval1=0//defines the first two digits val2=1tmp= $val 1for ((i=0; i < $num; ++i)) do let tmp= $val 1+ $val 2 val1= $val 2 val2= $tmpdoneecho "$num: $tmp"

To run the program:

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Using recursion is still possible, but less efficient:

#!/bin/bashread num function fib () {num1=$1 if [$1-lt 3];then echo $num 1 return fi let--nu M1 val1=$ (fib $num 1) Let--num1 val2=$ (fib $num 1) Let ret= $val 1+ $val 2 echo $ret}ret=$ (fib $num) echo "$num : $ret "

To run the program:

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5. Convert the string of each line in a file, for example, convert "123abc456" to "456abc123"

While read linedo//uses the Cut tool for string interception num1=$ (Echo ${line} | cut-c-3)//intercepts all characters from the left 3rd character to the left num2=$ (Echo ${line} | cut-c 7 -)//intercept all characters from the 7th character of the left to the right str=$ (Echo ${line} | cut-c 4-6)//Intercept the 4th character to the 6th character between the left and the next characters//another string intercept way # num1=${line:0:3}# num2=${ line:6:3}# Str=${line:3:3} eval echo "${num2}${str}${num1} | tr [A-z] [a-z] "//Convert with TR tool Done<file

To run the program:

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Finish

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Shell Scripting Exercises