On Tue, Dec 27, 2011 at 12:57:55PM GMT, lina wrote:
> Hi,
>
> I have two questions, wish to get advice,
>
> Question 1:
>
> For a series of files:
>
> cat a_*.o* | grep "WARNING"
It's one of the useless uses of cat[0].
Use:
% grep WARNING a_*.o*
instead.
> some file like a_1.o12 has WARNING, but others does not have WARNING
>
> How can I let grep returns the filename?
% man grep
-l, --files-with-matches
Suppress normal output; instead print the name of each input file
from which output would normally have been printed. The scanning
will stop on the first match. (-l is specified by POSIX.)
> Question 2:
>
> ls . | xargs -i -t cp ./{} {}.bak
>
> How does xargs work,
>
> I checked google, :
Maybe it's time to start checking man instead ;^)
% man xargs
> -i : replace the string
--replace[=replace-str]
-i[replace-str]
This option is a synonym for -Ireplace-str if replace-str is
specified, and for -I{} otherwise.
This option is deprecated; use -I instead.
> -t print
--verbose
-t
Print the command line on the standard error output before
executing it.
> but still lack well understanding,
it's quite self explanatory ;^)
> 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,
How about:
% ls | xargs -I '{}' cp '{}' '{}'.bak
BTW, if you're only after copying the files with .bak appended to the
copied file name, this should suffice.
for i in `ls` ; do cp $i $i.bak ; done
There are other ways to do it as well.
> 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.
Good to hear that, but maybe you should start to reading more and
test a bit yourself before you write an email. It'll definitely be less
than two days to find a solution and sometimes it'll take less time to
find it in the manual than to write an email.
I appreciate the fact that you're a beginner but your "problems" are
NOT Debian-specific and ARE trivial to "resolve" so maybe it's time
to learn how to look for solutions yourself rather than others holding
your hand all the time, eh? ;^)
[0] http://partmaps.org/era/unix/award.html
All the best.
--
Raf
--
To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org
with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org
Archive: http://lists.debian.org/20111227140000.ga32...@linuxstuff.pl
