[NTLUG:Discuss] Extracting a column out of input

[Pesto]

Did you try dpkg -l | awk '{print $field}' ?  I don't have ubuntu so I
can't test...

pesto

On Sun, Jan 24, 2016 at 9:11 PM, Leroy Tennison <leroy.tennison at verizon.net>
wrote:

> The context is I want to extract only the package name out of Ubuntu's
> 'dpkg -' where the first column is the install status, the second the
> package name and the rest a description.  More generally though I want to
> know how to extract any column of data out of a multi-column list.  I've
> searched the web and found one way to do it but would like to have the
> flexibility of others without having to resort to awk, perl, etc.  My sense
> is that there is enough bash experience in this group that I can get an
> answer here a lot quicker than trying to find exactly what I want on the
> web.  What I have so far is:
>
> dpkg -l | while read col1 col2 col3; do echo $col2; done
>
> I was trying
>
> for i in `dpkg -l`; do read col1 col2 col3; echo col2; done
>
> but read is expecting stdin.  Adding 'xargs -l1' in front produced "No
> such file or directory".
>
> Then I tried
>
> while read col1 col2 col3; do echo $col2; done < ls -l
>
> to get a syntax error and
>
> while read col1 col2 col3; do echo $col2; done < `ls -l`
>
> to get "Ambiguous redirect"
>
> What am I doing wrong and what should I do?
>
>
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