Jefromi 是正确的；这是我认为你想要的逻辑:

Jefromi is correct; here is the logic I think you want:

#!/bin/bash
# this is "test.sh"

if [ $(pidof -x test.sh| wc -w) -gt 2 ]; then 
    echo "More than 1"
    exit
fi

echo "Only one; doing whatever..."