在shell脚本中检查两个并行运行后台命令的退出状态

Question

假设我在shell脚本中并行运行两个命令，例如

/cmd1 &  
pid1=$!

/cmd2 &  
pid2=$!

status1=    # what should go here?

status2=$?  # I know this will have status of previous background process only

我希望只有两个命令都具有干净的退出状态才能继续 如何查看第一个后台进程的状态。

Answer 1

一种解决方案是使用GNU Parallel with --joblog，此处显示2个命令exit 0和exit 1：

(echo exit 0; echo exit 1) | parallel --joblog /tmp/foo
cat /tmp/foo
Seq     Host    Starttime       Runtime Send    Receive Exitval Signal  Command
1       :       1359451838.09   0.002   0       0       0       0       true
2       :       1359451838.093  0.002   0       0       1       0       false

Exitval列将给出退出值。如果其中一个作业失败，GNU Parallel也将返回非零值：

(echo exit 0; echo exit 1) | parallel && echo Do this if none fail

或同等的：

parallel ::: "exit 0" "exit 1" && echo Do this if none fail

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