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Remove every line with specific string, and also the one above and below it

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# 1  
Old 05-21-2014
Remove every line with specific string, and also the one above and below it
I would like to identify every line with a specific string, in this case: "Mamma".
I would like to remove that line, and also the line above it and below it. So the below

Code:
Where are all amazing Flats
Look At The Great Big White
Hey There Hot Mamma
You Are So hot Baby
I wish You were Mine
Hee How Yee Haw
Hey There Hot Mamma
Wait A minute
Hee Haw Yee Haw
Hey There Hot Mamma
A song Is Here
Make me a List

Becomes

Code:
Where are all amazing Flats
I wish You were Mine
Make me a List


I was wondering if anyone could help me out? I've googled but it is a little complex for Google

---------- Post updated at 05:14 PM ---------- Previous update was at 05:07 PM ----------

I think this might work

sed -n '/Mamma/{N;s/.*//;x;d;};x;p;${x;p;}' file | sed '/^$/d'
Last edited by jim mcnamara; 05-21-2014 at 06:10 PM.. Reason: code tags
# 2  
Old 05-21-2014
An awk approach by scanning file twice:
Code:
awk 'NR==FNR{if($0~/Mamma/) A[NR]=$0;next}!(A[FNR-1]) && !(A[FNR]) && !(A[FNR+1])' file file

# 3  
Old 05-22-2014
Perhaps ed or ex would be simpler:
Code:
ed -s file <<-"EOF"
	g/Mamma/.-1,.+1d
	1,$p
EOF

And, if you want to modify the input file instead of just print the file contents with the specified lines deleted, change the:
Code:
	1,$p

to:
Code:
	w

These 4 Users Gave Thanks to Don Cragun For This Post:
ctsgnb rbatte1 Subbeh vgersh99
# 4  
Old 05-22-2014
Hi.

Solution with a relative of grep, cgrep:
Code:
#!/usr/bin/env bash

# @(#) s1	Demonstrate match+previous+successor, then invert to delete; cgrep.
# See: http://sourceforge.net/projects/cgrep/

# Utility functions: print-as-echo, print-line-with-visual-space, debug.
# export PATH="/usr/local/bin:/usr/bin:/bin"
LC_ALL=C ; LANG=C ; export LC_ALL LANG
pe() { for _i;do printf "%s" "$_i";done; printf "\n"; }
pl() { pe;pe "-----" ;pe "$*"; }
db() { ( printf " db, ";for _i;do printf "%s" "$_i";done;printf "\n" ) >&2 ; }
db() { : ; }
C=$HOME/bin/context && [ -f $C ] && $C column cgrep

FILE=${1-data1}

pl " Input data file $FILE (columnized):"
column $FILE

pl " Results:"
cgrep -D -V -1 +1 Mamma $FILE

exit 0

producing:
Code:
$ ./s1

Environment: LC_ALL = C, LANG = C
(Versions displayed with local utility "version")
OS, ker|rel, machine: Linux, 2.6.26-2-amd64, x86_64
Distribution        : Debian 5.0.8 (lenny, workstation) 
bash GNU bash 3.2.39
column - ( /usr/bin/column, 2007-11-20 )
cgrep ATT cgrep 8.15

-----
 Input data file data1 (columnized):
Where are all amazing Flats	Hey There Hot Mamma
Look At The Great Big White	Wait A minute
Hey There Hot Mamma		Hee Haw Yee Haw
You Are So hot Baby		Hey There Hot Mamma
I wish You were Mine		A song Is Here
Hee How Yee Haw			Make me a List

-----
 Results:
Where are all amazing Flats
I wish You were Mine
Make me a List

The cgrep code is at the URL noted in the script; it needs to be compiled.

Best wishes ... cheers, drl
# 5  
Old 05-22-2014
Another way to do it in awk:
Code:
awk '/Mamma/ { s=x ; getline ; next } s { print s } { s=$0 } END { print s }' file

# 6  
Old 05-22-2014
Assuming no duplication in records, could you get away with two grep commands?:-
Code:
grep -B1 Mamma infile > tempfile
grep -vf tempfile infile > outfile


Have I missed the point in trying to make it too simple?
Code:
# cat input_file                                                  
Where are all amazing Flats
Look At The Great Big White
Hey There Hot Mamma
You Are So hot Baby
I wish You were Mine
Hee How Yee Haw
Hey There Hot Mamma
Wait A minute
Hee Haw Yee Haw
Hey There Hot Mamma
A song Is Here
Make me a List

# grep -B1 Mamma input_file>/tmp/tfile$$                          

# cat /tmp/tfile$$                                                
Look At The Great Big White
Hey There Hot Mamma
--
Hee How Yee Haw
Hey There Hot Mamma
--
Hee Haw Yee Haw
Hey There Hot Mamma

# grep -vf /tmp/tfile$$ input_file      
Where are all amazing Flats
You Are So hot Baby
I wish You were Mine
Wait A minute
A song Is Here
Make me a List

#




Robin
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