Write point shell--command line arguments every day

1, reading parameters: Positional parameter variable is the standard number: $ $ is the program name, "$" is the first parameter, and the second argument is ...

 1  #!/bin/bash  2   # using one command line parameter   3  4  factorial=1  5  for  (number = 1 ; <= $1 ; Number++ 6   do  7  factorial=$[$factorial * $number]  8  done  9  Span style= "COLOR: #0000ff" >echo  the factorial of $1  is $factorial 

Perform:

#./test1. SH 5  5

2. To enter multiple command-line options, each parameter must be separated by a space on the command line:

  1 #!/bin/bash  2  # Testing command line  parameters3    4 total=$[$1 * $2  ]  5echo The first parameter is $ 1  6 Echo The second parameter is $2  7echo The total value is $total

Perform:

#./test2. SH  3 4  3 4

3. If the script requires more than 9 command-line arguments, add curly braces around the variable numbers:

  1 #!/bin/bash  2  # handling lots of parameters  3   4 total=$[${} * ${one}]  5echo The tenth parameter is ${ Ten }.   6 Echo The eleventh parameter is ${one-by  -one}. 7 Echo The total is $total

Perform:

#./test4. SH 1 2 3 4 5 6 7 8 9 Ten  One    ten

4. Test parameters

  1#!/bin/Bash2# Testing parameters before use3   4 if[-N" $"] #-N parameter Tests if $ (first argument) is null5  Then  6     EchoHello $1, glad to meet. 7 Else  8     Echo "Sorry, You do not identify yourself"  9 fi

Perform:

#./test7. SH Sorry, you do not identify yourself. /test7. SH Frankhello Frank, glad to meet.

5. Special parameter variable (parameter Count $#)

  1 #!/bin/bash  2  #  gettingthe number of parameters3Echo There were $# parameters supplied.

Perform:

#./test8. SH  0 parameters supplied.


There were 3 parameters supplied.

6, the total number of test parameters before using parameters

  1#!/bin/Bash2# Testing Parameters3   4 if[$#-ne2 ]  5  Then  6     EchoUsage:test a B7 Else  8Total=$[$1+ $2 ]   9     EchoThe total is $totalTen fi  

Perform:

#./test9. SH 1 2  3

#./test9.sh
Usage:test a B

7, do not need to know how many parameters, grab the last parameter ${!#}

  1 #!/bin/bash  2 params=$#  3echo the number of parameter is $params  4echo last parameter is ${!  #}                                   

Perform:

sh test10. SH 1 2 3 4 4  5  #参数的总个数
 Last 4    #最后一个参数的值

8. $* [EMAIL protected] variable provides quick access to all parameters, $* variable saves all arguments supplied on the command line as a single word, and the [email protected] variable treats all arguments supplied on the command line as multiple independent words in the same string.

  1 #!/bin/bash  2 # testing $* and [email protected]  3   4  echo"Using The \$* method: $*"  5Echo " Using the \[email Protected] method: [Email protected] "                                 

Perform:

#./test11 Rich Katie jessicausing the $* Method:rich Katie jessicausing The [email protected] Method:rich Katie Jessica

Difference:

  1#!/bin/Bash2# testing $*and [email protected]3Count=1 #赋值的时候注意不要有空格  4  forParaminch "$*"  5  Do  6     Echo "\$* parameter # $count = $param"  7count=$[$count +1 ]  8  Done  9  TenCount=1  One  forParaminch "[email protected]"  A  Do  -     Echo "\[email protected] parameter # $count = $param"  -count=$[$count +1 ]  the  Done~

Perform:

#./test12. SH rich Barbara Katie jessica$* parameter #1 = rich Barbara Katie Jessica[email protected] parameter #  1 = rich[email protected] parameter #2 = barbara[email protected] parameter # C8>3 = katie[email protected] parameter #4 = Jessica

As you can see, $* will treat all parameters as a single singular, while the [email protected] variable will handle each parameter separately.

Write point shell--command line arguments every day