Linux series-shell learning notes (Continued 1) process user input,-shell learning notes

Linux series-shell learning notes (Continued 1) process user input,-shell learning notes

1. Run the program with Parameters

$0 indicates the program name, $1 indicates the first parameter, $2 indicates the second parameter, and so on until the ninth parameter $9

# Vi factorial

#!/bin/shf=1for((i=1;i<=$1;i++))do        f=$[ $f * $i]doneecho $f

Test:

[root@master test]# ./factorial 5120

NOTE: If there are multiple parameters, each parameter must have a space. If a parameter contains a space, it must be enclosed by single quotation marks or double quotation marks.

2. Read program name

Compile scripts that execute different functions based on the script name used

# Vi addem

#!/bin/shname=`basename $0`echo $nameif [ $name = "addem" ]then        echo $[$1+$2]elif [ $name = "mulem" ]then        echo $[ $1 * $2]fi

# Cp addem mulem

Test:

[root@master test]# sh addem 3 47[root@master test]# sh mulem 33 399

3. Parameter count

You can use$ #To count the number of parameters.

You can use$ {! #}To obtain the parameter variable of the last command line, or params =$ #, and then get it with $ params.

4. Obtain all data

$ * And $ @ variables provide quick access to all parameters.

[Root @ master test] # vi test11 #! /Bin/sh # testing $ * and $ @ echo "Using the \ $ * method: $ *" echo "Using the \ $ @ method :$ @" test: [root @ master test] #. /test11 rich jjds fds qaa dsddUsing the $ * method: rich jjds fds qaa dsddUsing the $ @ method: rich jjds fds qaa dsdd

$ *: The stored data is equivalent to a single word;

$ @: The stored data is equivalent to multiple independent words.

5. shift variable

Shift can be used to move all parameters one by one, $1 will be transferred, and the last $ # size will be reduced by 1

Shift 2 indicates moving two digits at a time

Whether the input parameter is not null: if [-n $1] indicates to judge whether $1 is null.

6. search options

# Vi test12

#!/bin/sh# extracting command line options as parameterswhile [ -n "$1" ]do        case "$1" in        -a) echo "-a option" ;;        -b) echo "-b option" ;;        -c) echo "-c option" ;;        *) echo "$1 is not an option" ;;        esac        shiftdone

Test:

[root@master test]# ./test12 -a-a option[root@master test]# ./test12 cc is not an option[root@master test]#

7. getopt and getopts commands

 

8. Get user input

# Vi test13

#! /Bin/shecho "please enter you name:" read nameecho "hello $ name, where come to here" test: [root @ master test] #. /test13please enter you name: hahahahello haha, where come to here

You can directly follow the specified prompt after reading:

read –p "please entry you age:" age

You can also use-t to set the timer.

read –t 5 –p "please entry you age:" age

Other parameters:

-S is implicitly read and data is displayed, but the read command sets the text color to the same as the background color;

9. read data from a file

# Vi test15

#!/bin/shcount=1cat test | while read linedo        echo "Line $count: $line"        count=$[$count + 1]doneecho "finish file!"

Test

[root@master test]# ./test15Line 1: #!/bin/shLine 2: if dateLine 3: thenLine 4: echo "it worked!"Line 5: fiLine 6: echo "this is a test file"Line 7: echo "this is a test file"finish file!