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Unix command line queue utility (github.com)
52 points by evandrix 3943 days ago
6 comments
justin_vanw 3943 days ago 

   $ mkfifo ~/.jobqueue
   $ parallel :::: ~/.jobqueue
now, from another terminal:

   echo ls > ~/.jobqueue
Tada!

for a remote job queue, use nc instead of a fifo

for a job queue with a buffer, use a file, and run $ parallel :::: <(tail -f thefile) you can even truncate the file from time to time.

Of course, this doesn't capture the context you are in, such as your current directory or the value of shell variables.

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kovek 3943 days ago
Here is an alternative:

  tty1$ mkfifo /tmp/jobqueue
  tty1$ eval $(tail -n 1 /tmp/jobqueue)
And then, in another terminal:

  tty2$ echo ls > /tmp/jobqueue
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giis 3943 days ago
What's 'parallel'? Is it a *nix command? Looks like its not available on Fedora box
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teraflop 3943 days ago
Yes, it's a GNU tool. Try "yum install parallel".

http://www.gnu.org/software/parallel/

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kovek 3943 days ago
This stackoverflow answer[0] shows how you can queue jobs even after you start running other processes in your queue. Essentially, you can do:

  sleep 2; echo "A" && sleep 2 ; echo "B" && sleep 2 ; echo "C" 
  # Quickly Ctrl-Z
  fg && sleep 2 ; echo "D"
and you will see A\nB\nC\nD\n slowly printed out in your terminal.

[0]: http://superuser.com/a/345455

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CyberShadow 3943 days ago
Could you please add some usage examples or elaborate on when this tool would be useful? For example,

> building several targets of a Makefile

As opposed to `make && sudo make install` ?

> downloading multiple files one at a time

As opposed to `(wget url1 &) ; (wget url2 &)` ?

> or simply as a glorified `nohup`

As opposed to `nohup` ?

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cozzyd 3943 days ago
I imagine it's useful if you don't know all the commands you want to queue at the beginning.

For example:

    nq ./my_awesome_analysis /data/complicated_file_with_long_name.dat

    # um... what's the next file? 

    ls /data 
    nq ./my_awesome_analysis /data/even_more_complicated_path.dat

    man rsync
    nq rsync -avh --progress out* somewhere_else.net:
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jessaustin 3943 days ago
You don't need nq for that. Just kick off ./my_lame_analysis in the background whenever you want.
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cozzyd 3943 days ago
Yes but then they will execute at the same time instead of sequentially.
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shanemhansen 3943 days ago
How about:

    ./my_awesome_analysis /data/complicated_file_with_long_name.dat &
    # do some stuf
    wait
    ./my_awesome_analysis /data/even_more_complicated_path.dat
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e40 3943 days ago
It's still not equivalent, and it's more cumbersome.
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PeterWhittaker 3943 days ago
Thank you for making the comment I came to make!

The shells have had queueing for, well, a very, very long time....

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jschwartzi 3943 days ago
Which systems guarantee monotonic behavior for gettimeofday()? I can't think of any. I hope there's no behavior in nq which relies on monotonicity other than file naming, because otherwise you might run into some obscure issues.
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pwg 3943 days ago
How does this differ from task spooler:

http://vicerveza.homeunix.net/~viric/soft/ts/

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dsl 3943 days ago
cat list.txt | xargs -n 1 -P 20 wget

Queues up 20 concurrent downloads with wget, for example.

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icebraining 3943 days ago
You could also use a for loop. But as others pointed out, that doesn't allow you to add items to the queue after it has started.
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stonogo 3943 days ago
It does if you use a fifo instead of a text file. This is the difference between basic Unix literacy and actual Unix proficiency. I'm not being insulting; very few people take the time to learn the tools Unix provides. And naturally, a developer is going to be more interested in writing tools than most.
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icebraining 3942 days ago
I don't think you can use a fifo with xargs, though it'd definitively work with a loop. Even with text files, using tail -f.
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iokanuon 3942 days ago 

    tail -n+0 -f list.txt | xargs -n 1 -P 20 wget
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