Re: sometimes surprised/confused

[Lianheng Tong]

Hi,

I think the problem you have encountered is a problem associated with a possible misunderstanding how POSIX command lines are interpreted by the system, rather than a particular problem with parallel.

Best regards,

Lianheng

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Lianheng Tong                                    Tel: +44 79 1758 3822  

Room S4.02, Strand Building           Fax: +44 20 7848 2420  

Department of Physics                       lianheng.tong@kcl.ac.uk

Kings College London                                  

Strand, London WC2R 2LS, U.K.                         

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On 6 Jan 2014, at 10:35, ChessDoter wrote:

hello,

far from being a power user with linux...

... i happen to play with parallel...

and get confused/surprised at times. Like so:

echo this should not happen | xargs -n 1 echo | parallel --dry-run -n 2 echo `echo {}`

First, i was not able to separate the 4 words into different arguments with --colsep ' ', so that is why i used xargs in the mix.
Then, i did not expect --dry-run to allow for execution of the embedded `echo` command.

Ok, i can imagine scenarios, when this comes in handily...

My current conclusion is: be VERY careful with this powerful tool, test thoroughly before execution but even then... (can i trust it?) beware of unexpected side-effects.

just my 2 cents