Why no data is displayed from file after writing in Python

Question

Following is my code

#!/usr/bin/python
from sys import argv
x, file_name = argv
print "planning to erase file %r. " , file_name
tgt=open(file_name,'r+')
print "deleting"
tgt.truncate()
print tgt.read()
print " no lines "
print "closed : ", tgt.closed
print "mode : ", tgt.mode
l1 = raw_input("line1 : ")
l2 = raw_input("line2 : ")
l3 = raw_input("line3 : ")
tgt.write(l1)
tgt.write('\n')
tgt.write(l2)
tgt.write('\n')
tgt.write(l3)
print "after writing"
print tgt.read()
print "Going to replace "
tgt.close()

Last read statement does not display data. But the file is updated with 3 lines I entered. Can any help

Avinash Raj · Accepted Answer · 2015-07-17 13:48:51Z

3

You need to read the file once again by moving the cursor to the top

tgt.seek(0)
print tgt.read()

answered Jul 17, 2015 at 13:48

Avinash Raj

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2 Comments

kylieCatt Over a year ago

I believe on Windows systems you might also need to close the file first before the changes are added. I'm not sure though. Although that could only apply to actually opening the file to view it as opposed to directly accessing the file object.

NightShadeQueen Over a year ago

You can call flush(), I think? It's buffering, python on Linux does it too.

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