Command: command & type

 

command

command 只能跳过function,而不能跳过shell builtin

 

 

三个选项 -vV都是打印 -p 使用 default PATH 执行命令

 

 

bash默认PATH: /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin

 

 

 

getconf retrieve the values POSIX or system configuration variables

command -p getconf PATH

 

 

 

Reimplement command

function command() {
    echo 'execute shell builtin `command` with args' "$@"
    builtin command "$@"
}

 

 

 

type

 

 

 

 

#!/bin/env sh

source /etc/rc.d/init.d/functions

function pwd(){
        action pwd true
}

echo -e '\e[7;45mDirect run pwd\e[0m'

pwd

echo -e '\e[5;42mRun command pwd\e[0m'

command pwd

if command -v pwd &> /dev/null;then
        action 'pwd exists?' true
else
        action 'pwd exists?' false
fi


if command -pv pwd >& /dev/null;then
        action 'System pwd exists?' true
else
        action 'System pwd exists?' false
fi