[英]Python3: os.system not redirecting stdout
As mentioned in the title.如标题所述。 I have this in my code:我的代码中有这个:
os.system("./vpr/vpr " + config + " " + file_name + " --seed " + str(seed) + " &> " + str(bench_name) + "-" + str(seed) + ".stdout")
Which has a lot of variables, but it simply evaluates to this (I know for sure because I have a print statement right before the os.system
line):它有很多变量,但它只是简单地评估为这个(我肯定知道,因为我在os.system
行之前有一个打印语句):
./vpr/vpr vpr/k6_N10_40nm.xml vpr/blif/clma.blif --seed 0 &> clma-0.stdout
The command actually runs fine, but the redirection does not!该命令实际上运行良好,但重定向没有! The file clma-0.stdout
gets created but remains empty, and I still get the entire stdout on my terminal.文件clma-0.stdout
被创建但仍然是空的,我仍然在我的终端上获得整个标准输出。
What is the solution for that?什么是解决方案? What am I doing wrong?我究竟做错了什么? I'm using python-3.7 on Ubuntu 19.10我在 Ubuntu 19.10 上使用 python-3.7
Thanks.谢谢。
I'm not sure why exactly, but it seems like os.system
is using Dash (Ubuntu's default scripting shell), not Bash, so &>
is not supported.我不确定为什么会这样,但似乎os.system
使用的是 Dash(Ubuntu 的默认脚本外壳),而不是 Bash,因此不支持&>
。 What happens instead is the command is backgrounded, and the file is truncated.相反,命令是后台运行的,并且文件被截断。 That is, command &> filename
is equivalent to command &; > filename
即command &> filename
等价于command &; > filename
command &; > filename
. command &; > filename
。
To fix it you could simply use the equivalent redirection, > filename 2>&1
.要修复它,您可以简单地使用等效的重定向> filename 2>&1
。
I think that's because you are trying to do it using system command, not Bash which supports these I/O redirection flags.我认为这是因为您正在尝试使用系统命令来执行此操作,而不是使用支持这些 I/O 重定向标志的 Bash。
Try this one with shell=True
https://docs.python.org/2/library/subprocess.html#subprocess.call试试这个shell=True
https://docs.python.org/2/library/subprocess.html#subprocess.call
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