Re: which is the best command to use

[lina <lina.lastname@gmail.com>]

On Tuesday 27,December,2011 08:57 PM, lina wrote:
> Hi,
>
> I have two questions, wish to get advice,
>
> Question 1:
>
> For a series of files:
>
> cat  a_*.o* | grep "WARNING"
>
> some file like a_1.o12 has WARNING, but others does not have WARNING
>
> How can I let grep returns the filename?

I wrote a very-low-level and not-work-as-expected one,

#!/bin/sh

for filename in *.o*

do
#echo $filename
a= cat $filename | grep "WARNING"
        if [ a ]
        then
                echo $filename
        fi

done

Please give me some advice,

Best regards,

> Question 2:
>
> ls . | xargs -i -t cp ./{} {}.bak
>
> How does xargs work,
>
> I checked google, :
> -i : replace the string
> -t print
> but still lack well understanding,
>
> how those xargs organise things,
>
> and
> $ ls .
> a.txt b.txt
>
> above will give a.txt.bak b.txt.bak
> ls | xargs -i cp ./{} {basename {}.bak}
> definitely not work,
>
>
> Sorry I send it to debian list, I asked on another bash list, for two 
> days the second question, no one replied. I have much more faith in 
> this list.
>
> WIth all the best regards,