錯誤：在命令中找不到ps命令

Question

我在執行此打印'hello'的bash腳本時出錯，直到後臺進程繼續執行。

ps command not found 

我已經做了幾次之前，但不知道爲什麼我這次得到錯誤。

./a.sh & 
while ps -p $! > /dev/null; do 
     echo hello 
done 

Answer 1

調試這個問題，我建議如下

nohup ./a.sh & 
p1=$! 

while ps -p $p1 
do 
    echo hello 
    sleep 1 
done 

Answer 2

這並不解決您的明顯PATH問題，但有一個簡單的方法你想要比調用ps反覆做什麼。

# Start your script in the background, remembering its process ID 
./a.sh & A_PID=$! 

# Start another background job that echos hello (once per second, to 
# avoid a flood of hellos). Remember its process ID as well 
(while : ; do echo hello; sleep 1 done) & LOOP_PID=$! 

# Now wait for a.sh to finish... 
wait $A_PID 

# ... and kill the hello job 
kill $LOOP_PID