I have been playing with Python for almost five days and I honestly enjoy it.
I have this challenge and I couldn't solve it.
The challenge is to repeat the output of top command every 10 seconds and save it into a file.
Here is what I have done so far.
import time, os, threading
def repeat():
print(time.ctime())
threading.Timer(10, repeat).start()
f = open('ss.txt', 'w')
top = os.system("sudo top -p 2948")
s = str(top)
text = f.write(s)
print(text)
repeat()
The main problem here is that a call to top does not terminate immediately but runs continuously in a loops to display new data. You can change this behaviour by specifying the -n1 option (-n allows you to specify the number of iterations).
Try something like this:
import subprocess
## use the following where appropriate within your loop
with open("ss.txt", "w") as outfile:
subprocess.call("top -n1 -p 2948", shell=True, stdout=outfile)
It is advisable to use subprocess for invoking another process. You need to pass the file object of the file where you want to write output.
e.g.
import time, os, threading, subprocess
def repeat():
print(time.ctime())
threading.Timer(10, repeat).start()
with open('ss.txt', 'w') as f:
subprocess.call(["sudo","top","-p","2948"],stdout=f)
This should save the output of command to a file which you can read later.
You can also use the time.sleep() function, and wait for 10 seconds before continuing.
Not sure whether this is what you want...
import time,os
def repeat(seconds,filename):
while True:
print(time.ctime())
f = open(filename, 'w')
top = os.system("sudo top -p 2948")
s = str(top)
time.sleep(seconds)
f.write(s)
repeat(5,'ss.txt')
Also
f.write returns None, as it writes on the file, not returning
any value, so it is useless storing that value. subprocess module. (thx to @ajm)subprocess.Popen() has a lot of functionality(tools), so it can replace many other 'tools', (see here) so you may consider that too.First, your code is not formated properly, it should look more like that:
import time, os, threading
def repeat():
print(time.ctime())
threading.Timer(10, repeat).start()
f= open('ss.txt', 'w')
top= os.system("sudo top -p 2948")
s=str(top)
text = f.write(s)
print text
repeat()
Then, you might want to look into subprocess module - its the more modern and kosher way to call external commands than os.system. However, if your code works, what's the actual problem?
