Is there a way to run process parallelly in the loop of a bash script

Question

Possible Duplicate:
Parallelizing a for loop

The original code might look like this:

 for i in *; do something.py $i; done

I was wondering whether I can run these jobs parallelly in the backgroud, such as:

 for i in *; do something.py $i &; done

I tried and found the & here won't work..

Moreover, a better way might be that bash allow 8 jobs(or any number) run together in the queue in background, but I don't know how to do that...

Does anyone have ideas about this? Thanks!

Not very much a duplicate, that one doesn't concern the problem with `&` though — daisy, Oct 31 '12 at 08:49

Gilles Quénot · Accepted Answer · 2012-10-31T03:11:51.400

7

Simply remove the ; character, so in final :

 for i in *; do something.py $i & done

And for running N instance of your script at the same time, see man 1 parallel

edited Oct 31 '12 at 03:11

answered Oct 31 '12 at 02:52

Gilles Quénot

Added some hints about `parallel` – Gilles Quénot Oct 31 '12 at 03:12
2

It isn't necessary to comment after editing a post: its a wiki, the edit history is recorded... – jasonwryan Oct 31 '12 at 04:06
Interesting, you don't need the semicolon before `done` – daisy Oct 31 '12 at 08:48
`&` is a command terminator like `;` and newline: also `&&` and `||`. See SHELL GRAMMAR in the bash manpage, or [here](http://www.gnu.org/software/bash/manual/bashref.html#Lists) – glenn jackman Oct 31 '12 at 13:40

1 Answers1