Linux Shell Script Raiders (1.12)

1.12 Functions and Parameters

• Like other scripting languages, Bash also supports functions and can pass parameters.

1.12.1 function definition and parameter transfer

#!/bin/bash  function fname ()  #也可以用fname () instead of  {echo  $1 , $2        ;     #访问参数1和参数2  echo           "[email protected] " ;     #以列表的方式一次性打印所有参数  echo           "$*" ;     #类似于 [email protected], but the parameter is used as a single entity  return           0 ;  #返回值 } fname $1  $2   #执 row functions and pass parameters   

• $1 is the first parameter;$2 is the second parameter;$n is the nth parameter;$@ is expanded to "$1 ""$2 ""$3 ";$* is expanded to " 1c 2c$3 ", where C is the first character of the IFS.

1.12.2 recursive function

• In bash, functions also support recursive functions.

F(){    echo$1;    F hello;    1;}

1.12.3 Read command return value

• The return value is called the eject state , which can be used to analyze whether the command executes successfully or not. If the command exits successfully, the exit status is 0, otherwise it is not 0.

#!/bin/bashCMD="echo test"   #CMD为要执行的命令$CMD              #执行命令if-eq0 ]   #$?为退出状态then    echo"$CMD executed successfully"else    echo"$CMD executed unsuccessfully"fi

1.12.4 passing parameters to a command

• Commands in bash usually have multiple parameters, and the parameters of the command can be passed in different formats. Assuming that-p,-v is an available option, K n is another acceptable parameter, and you can accept a file name as a parameter, then several ways are equivalent:

-p-v-k1-pv-k1-vpk1-file-pvk1     #k N应该紧邻

1.12.5 Reference

• Linxu Shell Script Raiders

Linux Shell Script Raiders (1.12)