Immediately print a string on stdout without new line?

ruby-talk
1

Hi everyone!

I'm trying to do something like this:

print "Processing... "

#some fancy code that takes ages, or maybe:
sleep(3)

print "done\n"

I was expecting to get the following output on my console:

Processing... [and after 3 secs:]done

However, the script first waits 3 seconds and then writes the whole line
at once. If I change the first line to

print "Processing...\n"

everything works as expected. But that's not really what I want. Is
there another way of doing this?

Thanks, Janus

···

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2

Try this:

print "Processing... "
STDOUT.flush

sleep 3

puts "done"

STDOUT#flush will ensure that everything in the buffer will be printed, there and then

~ Ari
English is like a pseudo-random number generator - there are a bajillion rules to it, but nobody cares.

···

On Jul 15, 2008, at 5:09 PM, Janus Bor wrote:

Hi everyone!

I'm trying to do something like this:

print "Processing... "

#some fancy code that takes ages, or maybe:
sleep(3)

print "done\n"

I was expecting to get the following output on my console:

Processing... [and after 3 secs:]done

However, the script first waits 3 seconds and then writes the whole line
at once.

3

Janus this works for me:

def processing
print "Processing... "
sleep(3)
print "done!"
end

processing

···

On Tue, Jul 15, 2008 at 3:09 PM, Janus Bor <janus@urban-youth.com> wrote:

Hi everyone!

I'm trying to do something like this:

print "Processing... "

#some fancy code that takes ages, or maybe:
sleep(3)

print "done\n"

I was expecting to get the following output on my console:

Processing... [and after 3 secs:]done

However, the script first waits 3 seconds and then writes the whole line
at once. If I change the first line to

print "Processing...\n"

everything works as expected. But that's not really what I want. Is
there another way of doing this?

Thanks, Janus
--
Posted via http://www.ruby-forum.com/\.

--
"Hey brother Christian with your high and mighty errand, Your actions speak
so loud, I can't hear a word you're saying."

-Greg Graffin (Bad Religion)

4

fedzor wrote:

Try this:

print "Processing... "
STDOUT.flush

sleep 3

puts "done"

STDOUT#flush will ensure that everything in the buffer will be
printed, there and then

Thank you! That does the trick...

Glen Holcomb wrote:

Janus this works for me:

def processing
print "Processing... "
sleep(3)
print "done!"
end

processing

Strange, on my machine (Ruby 1.86 on Linux) "Processing... " and "done!"
appear at the same time (after the 3 seconds).

···

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5

Another option ...

STDOUT.sync = true
print "Processing... "

The sync flag will cause the IO stream to be flushed after every write / print / puts.

Blessings,
TwP

···

On Jul 15, 2008, at 3:17 PM, fedzor wrote:

Try this:

print "Processing... "
STDOUT.flush

sleep 3

puts "done"

STDOUT#flush will ensure that everything in the buffer will be printed, there and then

6

Until reading fedzor's post I had completely forgotten that different
Operating systems behave differently. I'm on a Windows machine here at
work. Glad you got it fixed though.

···

On Tue, Jul 15, 2008 at 3:26 PM, Janus Bor <janus@urban-youth.com> wrote:

fedzor wrote:
> Try this:
>
> print "Processing... "
> STDOUT.flush
>
> sleep 3
>
> puts "done"
>
> STDOUT#flush will ensure that everything in the buffer will be
> printed, there and then
>

Thank you! That does the trick...

Glen Holcomb wrote:
> Janus this works for me:
>
> def processing
> print "Processing... "
> sleep(3)
> print "done!"
> end
>
> processing
>

Strange, on my machine (Ruby 1.86 on Linux) "Processing... " and "done!"
appear at the same time (after the 3 seconds).
--
Posted via http://www.ruby-forum.com/\.

--
"Hey brother Christian with your high and mighty errand, Your actions speak
so loud, I can't hear a word you're saying."

-Greg Graffin (Bad Religion)

7

Another option: print your message to stderr, not stdout. Stderr is
usually not buffered by the OS (for exactly this sort of reason).

Dave

···

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