shell 函数中的 x 是干啥的啊

[dengshuang]

贴代码

release="centos"

boot_start(){ if [[ x"${release}" == x"debian" || x"${release}" == x"ubuntu" ]]; then update-rc.d -f ${1} defaults elif [[ x"${release}" == x"centos" ]]; then chkconfig --add ${1} chkconfig ${1} on fi }

[dengshuang]

boot_start(){
if [[ x"${release}" == x"debian" || x"${release}" == x"ubuntu" ]]; then
update-rc.d -f ${1} defaults
elif [[ x"${release}" == x"centos" ]]; then
chkconfig --add ${1}
chkconfig ${1} on
fi
}

[laxenade]

https://stackoverflow.com/questions/1805663/shell-script-purpose-of-x-in-xvariable/

[dengshuang]

@laxenade 谢谢了