将shell脚本执行结果赋值给变量

Question

我有 shell 脚本。其中有：

./dtapi get_probability decision_tree simulated_diabetes_incidence_data_new.txt  AGE 70 weight 34 height 5.5 sex 0 ds1 34

现在我正在尝试使用 python 脚本执行此 shell 脚本并将结果存储到某个变量中。 test.py 包含 -

import os, sys
result = os.system("sh cmd_dtapi.sh")
print "Result is : ", result

但它的行为是这样的：

python test.py 
{"risk_of_disease":"2.122e-314"}Result is :  0

直接打印结果，赋值需要 0 .

如何将结果存储到某个变量中？

更新

跟随答案后 -

import subprocess
import json
result_process_output = subprocess.check_output("sh cmd_dtapi.sh")
result_json = json.loads(result_process_output)
result = result_json["risk_of_disease"]
print "Result is : ", result

给予

Traceback (most recent call last):
  File "test.py", line 3, in <module>
    result_process_output = subprocess.check_output("sh cmd_dtapi.sh")
  File "/usr/lib/python2.7/subprocess.py", line 566, in check_output
    process = Popen(stdout=PIPE, *popenargs, **kwargs)
  File "/usr/lib/python2.7/subprocess.py", line 710, in __init__
    errread, errwrite)
  File "/usr/lib/python2.7/subprocess.py", line 1327, in _execute_child
    raise child_exception
OSError: [Errno 2] No such file or directory

Answer 1

Here 是 os.system() 的描述：

Execute the command (a string) in a subshell. This is implemented by calling the Standard C function system(), and has the same limitations. Changes to sys.stdin, etc. are not reflected in the environment of the executed command. If command generates any output, it will be sent to the interpreter standard output stream.

这意味着，您的 shell 将 {risk_of_disease":"2.122e-314"} 打印到标准输出。

至于os.system() returning 0:

On Windows, the return value is that returned by the system shell after running command. The shell is given by the Windows environment variable COMSPEC: it is usually cmd.exe, which returns the exit status of the command run; on systems using a non-native shell, consult your shell documentation.

所以您的 shell 脚本的 return 代码是 0 并且它被分配给 result。所以从技术上讲，您已经将结果存储在变量中。

@edit:

要解决问题，您需要使用 subprocess 模块，它允许对系统调用进行更详细的操作。

import subprocess
import json
result_process_output = subprocess.check_output("sh cmd_dtapi.sh", shell=True)
result_json = json.loads(result_process_output)
result = result_json["risk_of_disease"]
print "Result is : ", result

将shell脚本执行结果赋值给变量

Assigning shell script execution result to variable

python

shell

system

sh