爲什麼os.system（）放置在for循環時運行？

Question

我有以下的（僞）代碼：

import os 

for s in settings: 
    job_file = open("new_file_s.sh", "w") 
    job_file.write("stuff that depends on s") 
    os.system(command_that_runs_file_s) 

不幸的是，什麼情況是，對應於s = settings[0]文件不被執行，但隨後s = settings[1]執行。顯然，os.system()不喜歡運行最近使用open()創建的文件，尤其是在for循環的相同迭代中。

對我的修復是確保通過os.system()執行任何文件中的for循環先前迭代初始化：

import os 

# Stagger so that writing happens before execution: 
job_file = open("new_file_settings[0].sh", "w") 
job_file.write("stuff that depends on settings[0]") 

for j in range(1, len(settings)): 
    job_file = open("new_file_settings[j].sh", "w") 
    job_file.write("stuff that depends on settings[j]") 

    # Apparently, running a file in the same iteration of a for loop is taboo, so here we make sure that the file being run was created in a previous iteration: 
    os.system(command_that_runs_file_settings[j-1]) 

這顯然是荒謬的，笨拙的，所以我該怎麼做才能解決這個問題問題？ （順便說一句，同樣的行爲發生在subprocess.Popen()）。

Answer 1

與代碼的問題：

import os 

for s in settings: 
    job_file = open("new_file_s.sh", "w") 
    job_file.write("stuff that depends on s") 
    os.system(command_that_runs_file_s) 

是你是不是收盤job_file，使文件仍處於打開狀態（而不是刷新）當您運行的系統調用。

做job_file.close()，或更好：使用上下文管理器來確保文件關閉。

import os 

for s in settings: 
    with open("new_file_s.sh", "w") as job_file: 
     job_file.write("stuff that depends on s") 
    os.system(command_that_runs_file_s)