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Help me to print to screen as well as log

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  Help me to print to screen as well as log Himanshu Garg <hgarg.india@gmail.com> - 2013-11-22 05:51 -0800
    Re: Help me to print to screen as well as log Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-11-22 14:15 +0000
      Re: Help me to print to screen as well as log Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-11-22 15:38 +0000
    Re: Help me to print to screen as well as log Peter Otten <__peter__@web.de> - 2013-11-22 15:26 +0100
    Re: Help me to print to screen as well as log Himanshu Garg <hgarg.india@gmail.com> - 2013-11-23 05:11 -0800
      Re: Help me to print to screen as well as log Dave Angel <davea@davea.name> - 2013-11-23 18:02 -0500
    Re: Help me to print to screen as well as log Miki Tebeka <miki.tebeka@gmail.com> - 2013-11-23 16:23 -0800
    Re: Help me to print to screen as well as log Himanshu Garg <hgarg.india@gmail.com> - 2013-11-23 23:00 -0800

#60221 — Help me to print to screen as well as log

I want that print "hello" should appear on screen as well as get saved in a log file.

How can I accomplish this?

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#60225

On Fri, 22 Nov 2013 05:51:21 -0800, Himanshu Garg wrote:

> I want that print "hello" should appear on screen as well as get saved
> in a log file.
> 
> How can I accomplish this?

print "hello"
logfile.write("hello\n")


Does that satisfy your need? If not, please explain in more detail what 
you are trying to do, what you have already tried, and what happened when 
you tried it.



-- 
Steven

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#60238

On 22/11/2013 14:15, Steven D'Aprano wrote:
> On Fri, 22 Nov 2013 05:51:21 -0800, Himanshu Garg wrote:
>
>> I want that print "hello" should appear on screen as well as get saved
>> in a log file.
>>
>> How can I accomplish this?
>
> print "hello"
> logfile.write("hello\n")
>
>
> Does that satisfy your need? If not, please explain in more detail what
> you are trying to do, what you have already tried, and what happened when
> you tried it.
>

Fancy wasting vertical space like that, if you use a semi-colon you can 
save a whole lot of it like this

print "hello";logfile.write("hello\n") # :)

-- 
Python is the second best programming language in the world.
But the best has yet to be invented.  Christian Tismer

Mark Lawrence

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#60227

Himanshu Garg wrote:

> I want that print "hello" should appear on screen as well as get saved in
> a log file.
> 
> How can I accomplish this?

In Python 3 print() is a function -- you can replace it with a custom 
function that invokes the original print() twice.

In both Python 3 and Python 2 you can redirect sys.stdout/stderr to a custom 
object with a write() method.

If you are actually logging I suggest that you look into the logging package 
which allows multiple handlers, see

http://docs.python.org/3.3/howto/logging.html

You will need to replace your print() calls with

some_logger.info(message)

or similar.

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#60295

How can I write to the same file from two different scripts opened at same time?

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#60334

On Sat, 23 Nov 2013 05:11:11 -0800 (PST), Himanshu Garg 
<hgarg.india@gmail.com> wrote:
> How can I write to the same file from two different scripts opened 
at same time?

Using what version of python and on what OS?

Sone OS's will open the file exclusively by default. Others will let 
you stomp all over some other process' output.

Why not show us what you're trying and what happens and ask a much 
more specific question?

-- 
DaveA

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#60341

> I want that print "hello" should appear on screen as well as get saved in a log file.
> How can I accomplish this?
There are many ways to do this, here's one:

class MultiWriter(object):
    def __init__(self, *writers):
        self.writers = writers
        self.isatty = False

    def write(self, data):
        for writer in self.writers:
            writer.write(data)

    def flush(self):
        for writer in self.writers:
            writer.flush()


out = open('/tmp/log.txt', 'a')
import sys
sys.stdout = MultiWriter(sys.stdout, out)
print('hello')

IMO you're better with the logging package, see http://docs.python.org/2/howto/logging.html#configuring-logging for more details.

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#60350

I have simply opened file in append mode in linux.

script 1 :

file = open("output.log", "a")
file.write()
file.flush()

script 2:

file = open("output.log", "a")
file.write()
file.flush()

It writes properly to the file.

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