Python read() returns empty results

Question

Whenever I'm trying to run this python code, it returns a blank result / empty result. Can anyone help me with understanding why this happens?

#!/bin/python

import re
import time
import io

timecheck = open("/tmp/some.log", "r")
storeout = open("/tmp/storeout.txt", "w+")

for line in timecheck:
    if re.match("(.*)(Alarm obtained - type: KPI_CALCULATION)(.*)", line):
        out1 = line
        print >> storeout, line,

time1 = out1[11:19]
time2 = out1[164:172]
content = storeout.read()
print(content)
storeout.close()

log file contains the below entry: 2020-11-23 13:10:57.596 petrosocial-esp-shutdown-handler DEBUG c.p.e.s.s.ShutdownAlarmConsumerService:54 - Alarm obtained - type: KPI_CALCULATION, time: 2020-11-23T12:51:00.000Z, KPI alarm type: KPI_CALCULATION 2020-11-23 13:12:31.245 petrosocial-esp-shutdown-handler DEBUG c.p.e.s.s.ShutdownAlarmConsumerService:54 - Alarm obtained - type: KPI_CALCULATION, time: 2020-11-23T13:12:25.000Z, KPI alarm type: KPI_CALCULATION — Akhil S
– Akhil S, Commented Nov 23, 2020 at 13:54

larsks · Accepted Answer · 2020-11-23 13:49:26Z

2

When you write to a file, the current file position is located at the end of the file. If you call read without explicitly setting the file position, you'll get back an empty result because you're already at the end of the file.

To read the data you've already written, you need to instruct Python to start reading from the beginning of the file using the seek method:

storeout.seek(0)
content = storeout.read()

Alternately, you can close the file and then re-open it for reading.

answered Nov 23, 2020 at 13:49

larsks

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3 Comments

Akhil S Over a year ago

Can anyone help with how this output can be sent via email.

larsks Over a year ago

You should probably post a new question if you want help with that.

Akhil S Over a year ago

Done, can you please take a look stackoverflow.com/questions/64971241/…

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