Python os.system hangs for no reason?

Question

I don't think this has been asked before, but I read similar questions and none of them could solve my problem. I am making a file management in Tkinter using sqlite3. It has a 'write' button that, when clicked, opens a new notepad file using os.system. However, the code gets stuck here and doesn't proceed to the next further lines.

def openfile(uid, filename):
if filename=='':
    mb.showerror('Missing Input', 'Please specify a file name.')
else:
    try:
        os.system("notepad " +filename+".txt") #FREEZES HERE
        now=datetime.now()
        today= str(now.day) + '/' + str(now.month) +'/' + str(now.year)
        filecur.execute("SELECT * FROM File_Data")
        f=filecur.fetchall()
        print(f)
        filecur.execute("insert into File_Data (UID, FileName, Date_) values (?, ?, ?)", ( uid, filename, today))
        fileconn.commit()
    except:
        raise
        mb.showerror('Error','Looks like something is wrong. Please try again.')
        sys.exit(0)

If someone could help, that'd be great. Thank you!

Just making sure, `filename` doesn't already have `.txt`, right? Or else you're trying to open `filenmae.txt.txt`. — iz_, Nov 24 '18 at 08:07
Obligatory: don't use **os.system** - use the `subprocess` module: — Devanshu Misra, Nov 24 '18 at 08:24
Possible duplicate of [Blocking and Non Blocking subprocess calls](https://stackoverflow.com/questions/21936597/blocking-and-non-blocking-subprocess-calls) — stovfl, Nov 24 '18 at 09:40
`os.system` will wait until the process exits (i.e. until you close notepad). — bereal, Nov 24 '18 at 09:43
I learnt a bit about threading and applied it. It works well now. — Soumya Mukhija, Nov 25 '18 at 18:00

score 2 · Accepted Answer · answered Nov 24 '18 at 10:29

2

That's because os.system() does wait for its process to complete before returning.

Problem can be solved either by using threading or sub-process module.

Read more here: http://docs.python.org/library/subprocess.html

answered Nov 24 '18 at 10:29

Arbazz Hussain

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Python os.system hangs for no reason?

1 Answers1