Portal Home > Knowledgebase > Articles Database > LINUX BASH : keep the order in STD* output tunnels
LINUX BASH : keep the order in STD* output tunnels
| Posted by Mister Bark, 10-31-2012, 11:17 AM |
| Hi!
This will make a file "test" :
... and not :
Why and how make sure to keep the order of all STD*?
(I guess it's related to the buffers, that are probably separated for each output)
Please note that my question concerns bash, not perl (that program is just a test)
THANKS!
|
| Posted by FINESEC, 10-31-2012, 11:59 AM |
| Turn autoflashing on:
perl -e '$| = 1; print("a\n"); sleep(2); warn("WARN\n"); print("b\n");' >> test 2>&1
|
| Posted by Mister Bark, 10-31-2012, 12:01 PM |
| I know, thanks.
But as I said :
"Please note that my question concerns bash, not perl (that program is just a test)"
And that problem is related to bash because if you execute my perl test without redirecting to a file, it is in order in the terminal.
Last edited by Mister Bark; 10-31-2012 at 12:06 PM.
|
| Posted by FINESEC, 10-31-2012, 12:16 PM |
| Sorry, I didn't read the last line ;-)
It's not possible in bash afaik. You might try using stderr only or give this tool http://expect.sourceforge.net/example/unbuffer.man.html a try.
|
| Posted by Mister Bark, 10-31-2012, 12:44 PM |
| ah, that's interesting thanks
But I cannot find the program on the net nor in my distribs!
|
| Posted by FINESEC, 10-31-2012, 01:31 PM |
| Hmm, try this one:
http://man7.org/tlpi/code/online/dis...nbuffer.c.html
|
| Posted by Mister Bark, 10-31-2012, 03:00 PM |
| thanks!
I may look a bit stupid but... I've compiled many programs from source (configure and other stuff) but not from a single c file... how am I supposed to build that?
|
| Posted by FINESEC, 10-31-2012, 03:19 PM |
| Download and put all files to the same directory:
http://man7.org/tlpi/code/online/dis...nbuffer.c.html
http://man7.org/tlpi/code/online/dis...ty_fork.h.html
http://man7.org/tlpi/code/online/dis...ty_fork.c.html
http://man7.org/tlpi/code/online/dis...nctions.h.html
http://man7.org/tlpi/code/online/dis...nctions.c.html
http://man7.org/tlpi/code/online/dis...lpi_hdr.h.html
compile project using this command:
gcc *.c
Lemme know if that doesn't work.
|
| Posted by FINESEC, 10-31-2012, 03:44 PM |
| http://finesec.com/files/unbuffer.tar.gz <- all files are in this package
|
| Posted by Mister Bark, 10-31-2012, 05:39 PM |
| hehe thanks AWESOME
|
| Posted by MattF, 11-01-2012, 04:00 AM |
| It isnt bash nor perl
When using stdio stderr isnt buffered, stdout is buffered how so is depending on what its talking to, if its a file or pipe then its block buffered, if its a tty i.e. is_atty(fd) then its line buffered. This can be manipulated to some extent but a generally a concern that outputting app shouldnt do.
I suspect unbuffer is injecting it own LD_PRELOAD so its doesnt do buffering, Im going to explore more...
Loads of docs out there on stdio buffer that explain stuff better and more thoroughly
|
| Posted by Mister Bark, 11-01-2012, 09:14 AM |
| thanks for the explanation
|
Add to Favourites 
Print this Article
Also Read
Error 403 (Views: 744)
Shared Hosting
Shared Hosting
