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Split a file based on pattern in awk, grep, sed or perl

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Top Forums Shell Programming and Scripting Split a file based on pattern in awk, grep, sed or perl
# 1  
Old 06-20-2008
Split a file based on pattern in awk, grep, sed or perl
Hi All,

Can someone please help me write a script for the following requirement in awk, grep, sed or perl.

Code:
Buuuu xxx bbb
Kmmmm rrr ssss uuuu
Kwwww zzzz ccc
Roooowwww eeee
Bxxxx jjjj dddd
Kuuuu eeeee nnnn
Rpppp cccc vvvv cccc
Rhhhhhhyyyy tttt
Lhhhh rrrrrssssss
Bffff mmmm iiiii
Ktttt eeeeeee
Kyyyyy iiiii wwww
Rwwww rrrr sssss eeee
Rnnnnn xxxxxxccccc

I like to split the above file into 3 files like below,

file1:
Code:
Buuuu xxx bbb
Kmmmm rrr ssss uuuu
Kwwww zzzz ccc
Roooowwww eeee

file2:
Code:
Bxxxx jjjj dddd
Kuuuu eeeee nnnn
Rpppp cccc vvvv cccc
Rhhhhhhyyyy tttt
Lhhhh rrrrrssssss

file3:
Code:
Bffff mmmm iiiii
Ktttt eeeeeee
Kyyyyy iiiii wwww
Rwwww rrrr sssss eeee
Rnnnnn xxxxxxccccc

Basically the file need to be start with "B" record and start a new file when it come across another "B" record.

Appreciate you help.

Thanks

Kumar
Last edited by Yogesh Sawant; 06-20-2008 at 04:25 AM.. Reason: added code tags
# 2  
Old 06-20-2008
With (g)awk

Code:
awk 'BEGIN{RS="\n?B"} (NR-1){print "B" $0 > ("output-file_" NR)}' input-file

# 3  
Old 06-20-2008
Quote:
Originally Posted by ripat
With (g)awk

Code:
awk 'BEGIN{RS="\n?B"} (NR-1){print "B" $0 > ("output-file_" NR)}' input-file

Ripat, your solution doesn't give the desired output...

Try this:

Code:
awk '/^B/{close("file"f);f++}{print $0 > "file"f}' file

Regards
# 4  
Old 06-20-2008
I guess it would something like this in Perl:
Code:
perl -n -e '/^B/ and open FH, ">output_".$n++; print FH;' file

# 5  
Old 06-20-2008
Hi.

It is useful to know how to do custom splitting with awk, perl, etc., but one can often use utilities that are already present, such as csplit:
Code:
#!/bin/bash -

# @(#) s1       Demonstrate context splitting, csplit.

echo
echo "(Versions displayed with local utility \"version\")"
version >/dev/null 2>&1 && version =o $(_eat $0 $1) csplit
echo

FILE=${1-data1}

# Remove debris from previous run.

rm -f xx*

if uname -a | grep SunOS
then
  csplit -k $FILE '/^B/' '{99}'
else
  csplit -z $FILE '/^B/' '{*}'
fi

echo " Samples of output files:"
for file in xx*
do
  echo
  echo "-- $file --"
  head -2 $file
done

exit 0

Producing:
Code:
$ ./s1

(Versions displayed with local utility "version")
SunOS 5.10
GNU bash 3.00.16
csplit - no version provided for /usr/bin/csplit.

SunOS vm-solaris 5.10 Generic_120012-14 i86pc i386 i86pc
0
64
89
csplit: {99} - out of range
90
 Samples of output files:

-- xx00 --

-- xx01 --
Buuuu xxx bbb
Kmmmm rrr ssss uuuu

-- xx02 --
Bxxxx jjjj dddd
Kuuuu eeeee nnnn

-- xx03 --
Bffff mmmm iiiii
Ktttt eeeeeee

See man csplit for details (Solaris man page has some examples, unlike the man page in Linux) ... cheers, drl
# 6  
Old 06-20-2008
thank you all
All solutions really worked great. Now I have a choice. Thanks. Appreciate your help.

Code:
awk '/^B/{close("file"f);f++}{print $0 > "file"f}' input.txt

Code:
perl -n -e '/^B/ and open FH, ">output_".$n++; print FH;'  input.txt

Code:
csplit -k input.txt '/^B/' '{99}'

Last edited by rbatte1; 05-02-2017 at 05:56 AM.. Reason: Added CODE tags
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