I have a grep -o '100%' piped after a wget, so I'm only notified that wget completed the download, without useless information on screen. But each 100% is printed on a new line, and I don't like this flood! So, is there a way to tr the newlines into spaces, by piping tr after grep? All I got was no result, each time I tried...
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2 Answers
You would have gotten output eventually, but all in one go. This is due to buffering.
GNU grep has a --line-buffered to avoid output buffering. tr does input buffering with no apparent way to turn it off, so you can use awk instead:
wget -r -l 1 http://stackoverflow.com/ 2>&1 |
grep --line-buffered -o '100%' | awk '{printf("%s ", $0);}'
100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100%
answered Aug 9, 2016 at 21:45
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"You would have gotten output eventually, but all in one go." True, I confirmed now. I have not waited long because there were a lot of files to download, and it's very annoying to look at a screen that has no information about what is happening!– user4863385Commented Aug 9, 2016 at 22:11
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Are you sure that
--line-buffereddisables buffering? Bothmanandinfosays otherwise: "Use line buffering on output.". By the way, using it or not gives the same result: all100%only at the end.– user4863385Commented Aug 9, 2016 at 22:29 -
Are you trying the command as provided here or did you just add
--line-bufferedto your existing command? Commented Aug 9, 2016 at 22:45 -
I followed your instructions, but only after the
wget. So I maintained mywget(not recursive, input from file) and added what you suggested. Anyway, now I tested exactly what you suggested, except without the line break betweenwgetandgrep, and there was no100%until I aborted the process for taking too long without any output, and noticing that the download stopped at 18 items on the folder.– user4863385Commented Aug 10, 2016 at 0:03 -
That's pretty strange and I can't reproduce it. How about if you use
stdbuf -oL wget ...? Commented Aug 10, 2016 at 2:22
It's buffering, see Why no output is shown when using grep twice?. Just use awk:
$ wget -r -l 1 https://stackoverflow.com/ 2>&1 | awk 'match($0,/100%/){printf "%s ", substr($0,RSTART,RLENGTH)}'
100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100%
or probably more useful:
$ wget -r -l 1 https://stackoverflow.com/ 2>&1 | awk '/100%/{printf "."}'
...........
answered Aug 10, 2016 at 0:10
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I copied and executed the commands as they were written by you. Both downloaded 18 items, gave no output, and needed to be canceled (CTRL+C) to stop executing. I think, with this repeating to more than 1 solution of more than 1 replier, that other things needs to be checked. On which version of
wgetyour solution worked?– user4863385Commented Aug 10, 2016 at 5:00 -
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I was on 1.17.1, so I updated to 1.18 and tried again. Same non-results... So it's not
wgetthe culprit. Maybeawk? Here it's being caled mawk by man and info.– user4863385Commented Aug 10, 2016 at 21:01 -