GNU bug report logs - #7076
Command required

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Imran Shoaib <imran.shoaib <at> ubl.com.pk>
To: <bug-coreutils <at> gnu.org>
Subject: Command required
Date: Mon, 20 Sep 2010 15:10:48 +0500

[Message part 1 (text/plain, inline)]

How can we extract few characters from second or third line of a text
file using cut command of Linux OS?

 

For example: to get 7-10 characters from 3rd line of a text file is
required, what can be the command?

 

 

Regards,

 

Imran

 








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Message #10 received at 7076-done <at> debbugs.gnu.org (full text, mbox):

From: Bob Proulx <bob <at> proulx.com>
To: Imran Shoaib <imran.shoaib <at> ubl.com.pk>
Cc: 7076-done <at> debbugs.gnu.org
Subject: Re: bug#7076: Command required
Date: Mon, 20 Sep 2010 15:21:18 -0600

Imran Shoaib wrote:
> How can we extract few characters from second or third line of a text
> file using cut command of Linux OS?

In the future please send discussion questions concerning the
coreutils to the coreutils mailing list instead of the bug-coreutils.
The bug-coreutils mailing list is for bug reports only and every email
message opens up a bug in the bug tracking system.  I am closing this
bug report but discussion may continue.  Thanks.

A good place for general help questions is help-gnu-utils <at> gnu.org.

> For example: to get 7-10 characters from 3rd line of a text file is
> required, what can be the command?

I would use sed for this.  Don't print by default (-n) and then print
the 3rd line.

  $ printf "1234567890\n1234567890\n1234567890\n" | sed -n 3p

If you want specific characters then you can delete the unwanted
ones.  This is a contrived example:

  $ printf "1234567890\n1234567890\n1234567890\n" | sed -n '3{s/^..\(..\).*/\1/;p;}'

Or you can chain commands together.  Print only the third line to a
command that pulls apart fields.

  $ printf "11 12 13\n21 22 23\n31 32 33\n" | awk 'NR==3{print$2}'
  32

  $ printf "11 12 13\n21 22 23\n31 32 33\n" | awk 'NR==3{print $2, $3}'
  32 33

> This E-mail and any files transmitted with it are confidential and
> intended solely for the use of the individual or entity to which
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In the future please do not include such useless and annoying
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software mailing list.  If you cannot avoid this then please use one
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Bob

Message #13 received at 7076 <at> debbugs.gnu.org (full text, mbox):

From: Imran Shoaib <imran.shoaib <at> ubl.com.pk>
To: <7076 <at> debbugs.gnu.org>,
	<help-gnu-utils <at> gnu.org>
Subject: RE: bug#7076: closed (Re: bug#7076: Command required)
Date: Wed, 22 Sep 2010 10:33:49 +0500

[Message part 1 (text/plain, inline)]

Thanks for the details, but what if information is to be read from file
and not from command line pattern?

For example from attached file we need to read characters 15 to 22 of
line 3 and use these characters only as input in any other file. Please
advise.


Imran
-----Original Message-----
From: GNU bug Tracking System [mailto:help-debbugs <at> gnu.org] 
Sent: Tuesday, September 21, 2010 2:19 AM
To: Imran Shoaib
Subject: bug#7076: closed (Re: bug#7076: Command required)

Your bug report

#7076: Command required

which was filed against the coreutils package, has been closed.

The explanation is attached below, along with your original report.
If you require more details, please reply to 7076 <at> debbugs.gnu.org.

-- 
7076: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=7076
GNU Bug Tracking System
Contact help-debbugs <at> gnu.org with problems







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Message #16 received at 7076 <at> debbugs.gnu.org (full text, mbox):

From: Bob Proulx <bob <at> proulx.com>
To: Imran Shoaib <imran.shoaib <at> ubl.com.pk>
Cc: 7076 <at> debbugs.gnu.org, help-gnu-utils <at> gnu.org
Subject: Re: bug#7076: closed (Re: bug#7076: Command required)
Date: Wed, 22 Sep 2010 14:36:37 -0600

Imran Shoaib wrote:
> Thanks for the details, but what if information is to be read from file
> and not from command line pattern?

Then read the data from the file instead of the command line.

> For example from attached file we need to read characters 15 to 22 of
> line 3 and use these characters only as input in any other file. Please
> advise.

For that specific case using 'awk' is easiest for me.  In awk the FNR
variable is "the input record number in the current input file" or the
current line number.  Use it to only take action on the 3rd line of
the file.

  FNR == 3

Then the substr(s,i,n) function next seems easiest.  The substr() function
returns the substr from 's' starting at index position 'i' and
containing at most 'n' characters.  Since $0 is the current line
string we use that.

  substr($0,15,8);  # return characters 15 to 22 of the line.

Then print the result.  Putting that all together yieds this:

  $ printf "one\ntwo\nabcdefghijklmnopqrstuvwxyz\n" | awk 'FNR==3{print substr($0,15,8);}'
  opqrstuv

The command line example was how I developed the case.  Because then
everything is contained in the example and it can be shared.  You were
asking how to read a file.  Most utilities read files in the argument
list.  So to read a file simply place the file in the argument list.

  $ awk 'NR==3{print substr($0,15,8);}' /tmp/sample.txt
  DFLSDJF 

> This E-mail and any files transmitted with it are confidential and

Please do not include such useless and annoying disclaimers in your
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Bob

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