怎么理解这个CP

ljyl038

cp ${ALERT} ${BACKUP} >/dev/null 2>/dev/null
特别是 >/dev/null 2>/dev/null觉得不是很熟悉，这个是不是在把${ALERT}的信息做CP到${BACKUP}的时候，不管是否成功都把把过程写到/dev/null 2>/dev/null里面，也就是写到垃圾桶里面，而 cat /dev/null > ${ALERT}就是把写入垃圾桶中的信息从新写到${ALERT}

briangao

>/dev/null  means that if the CP command has any output to the screen, you want to redirect it to /dev/null so that you won't see it on the screen.

2>/dev/null means that if CP command generates any error message, you don't want to see it either.

kinney

复习下重定向,好久没用了