nixCraft

#1 (**permalink**) 08-30-2005, 10:34 AM

Hello friends,
I have a small question which is as follows. " I have a folder of 100 .txt files all of which have 26 lines of text data (not useful to me). From the 27th line, i have 2 columns of decimal data. Imagine it to be like
0.400 13.2345
0.402 13.6301
0.410 12.8842
........ ....
....
....(220 lines like thi

Now all i need is the second column (13.2345,13.6301,.etc.) from all these .txt files. All second column data from all the .txt files should be copied into a new file "sequentially"." How can we do this?
As for my attempt, i have tried doing a command line instruction like this
sed -n '27,$s/ *[^ ]* *$.*$/\1/w {o/p file}' {input .txt file}
However this doesnt work when i use a for loop in a shell script. I have also used the >> {output file name} option, but it isnt working.
I would be glad if anyone can give any suggestions.
thank you.

monk · #2 (**permalink**) 08-30-2005, 04:19 PM

Well not sure about sed code, but following should work

Code:

files="*.txt"
OFILE="/tmp/output"
# 220-26 so start from 27th line
LINES=193 
>$OFILE
for f in $files
do
tail -$LINES $f | awk '{ print $2 }' >> $OFILE
done

Open file $OFILE and see output ;test it and lemme know!

#3 (**permalink**) 08-31-2005, 12:39 AM

thanx monk,
that worked. I found out the output file has only column 2 of the data. but then the output file was far bigger than i expected. I assume it is because the data is written on a new line everytime. Like C file operations is it possible to but data next to each other? so that the file size will be exactly the no. of data multiplied by the bytes( here it would be 193 * 100 files * 8 bytes for long data). I want the data to be placed next to each other.
thanx again for that reply.......i didnt use awk i tried cut -f2 filename which didnt work out!

monk · #4 (**permalink**) 08-31-2005, 01:34 AM

Replace line

Code:

tail -$LINES $f | awk '{ print $2 }' >> $OFILE

with

Code:

DATA="$(tail -$LINES $f | awk '{ print $2 }')"

And then use $DATA as per your need.

#5 (**permalink**) 09-01-2005, 12:02 AM

monk,
perhaps the double quotes dont work. When i try to echo $DATA, all it displays is the same command "tail +LINES.............".
I understand that what u meant is to copy all the data into the variable DATA and then print it to a new file? am i right?
I have tried putting the right hand side within ` ` instead of " " but that didnt work out too.

tom · #6 (**permalink**) 09-01-2005, 12:23 AM

I'm not expert in scripting but I think you need to get your data in awk script/command itself. Just thought...

monk · #7 (**permalink**) 09-01-2005, 12:44 AM

Try following

Code:

DATA="$DATA $(tail -$LINES $f | awk '{ print $2 }')"

So it should look like as follows:

Code:

files="*.txt"
OFILE="/tmp/output"
# 220-26 so start from 27th line
LINES=193
>$OFILE
DATA=""
for f in $files
do
DATA="$DATA $(tail -$LINES $f | awk '{ print $2 }')" 
done

Lemme know...

#8 (**permalink**) 09-01-2005, 02:41 AM

I tried doing that....sorry for the delay .....being new to shell script........i am taking time to follow it.
I used the above code. I think it works though using echo $DATA gives me a stream of values

Also i am trying to output DATA to a new file which is not happening. I used ( DATA >>OFILE) but that gives me an error.

rockdalinux · #9 (**permalink**) 09-01-2005, 11:40 AM

Add echo $DATA at the end of loop:

Code:

files="*.txt"
OFILE="/tmp/output"
# 220-26 so start from 27th line
LINES=193
>$OFILE
DATA=""
for f in $files
do
DATA="$DATA $(tail -$LINES $f | awk '{ print $2 }')"
done 

echo $DATA>$OFILE

#10 (**permalink**) 09-02-2005, 01:09 AM

my apologies for not telling u that i did echo ( the last line) to OFILE.....my head was somewhere else when i replied to u. even when i did that i viewed the data (less /tmp/output) the data looked like this
2.3061^M8.6088^M...................

the thing was the file was still the same size as the previous output file which had newline in between..............
Right now what i am doing is to write a C program ( because i need to write it for some other application) and reading a floating pt. (or long for 8 byte

and also a character so that whatever this ^M is i can get rid of.
What do u say?

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