RE: bug#7076: closed (Re: bug#7076: Command required)

[Imran Shoaib]

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-d...@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 70...@debbugs.gnu.org.

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







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[Bob Proulx]

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

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Bob