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I have a string (or a list of strings) that is/are to be searched in all the files of a directory.  For example, if I am searching for ABC, and file1.txt contains ABC on line 6, then I want lines 6, 7, 8, and 9 from that file.  I want all such output to go to a new output file.

G-Man Says 'Reinstate Monica'
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Praveen Kashekar
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  • Please expand the question to include an example. – steve Jul 19 '15 at 16:55
  • For E.G: string=ABC, directory=DIR1(contains huge text files). i want to search 'ABC' in all the files of directory 'DIR1'. suppose if we have ABC string in 6th line of file1.txt means i need 6,7,8,9 to be copied to output file. This is simple example. but i have big list to be searched. – Praveen Kashekar Jul 19 '15 at 16:59

3 Answers3

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Perhaps this suits. Makes use of the grep -A (after-context) option, to output the matching line and the 3 subsequent lines. 

find . -name file\* -exec grep -A 3 ABC {} \; > result-filename

NOTE: You shouldn't place result-filename in directoryname. (See: grep: input file 'X' is also the output).

To cover multiple patterns:

find . -name file\* -exec egrep -A 3 'ABC|XYZ' {} \; > result-filename

Or multiple patterns from a file (thanks Evgeny Vereshchagin) :

find . -name file\* -exec grep -A 3 -f patterns.txt {} \; > result-filename
Community
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steve
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  • Instead of single string, If i have list of strings. how can i perform ? – Praveen Kashekar Jul 19 '15 at 17:38
  • put your strings in file patterns (one string per line) and run find dir -type f -exec grep -A 3 -f patterns {} \; >result – Evgeny Jul 19 '15 at 18:00
  • (1) +1 for grep -A.  (2) Why are you suggesting **-name file\*** as part of your answer?  The filename file1.txt was just an example; the OP never said that he’s looking for files whose names begin with file.  Perhaps you meant -type f?  (3) Why not just say grep -A 3 -f patterns.txt *?  The question is imprecise regarding the meaning of “all the files of a directory”.  If you need to include “hidden” files, use shopt -s dotglob.  If you need to recurse into subdirectories, say shopt -s globstar and use grep … **. – G-Man Says 'Reinstate Monica' Jul 19 '15 at 21:42
  • (3) Didn't like the grep -A 3 -f patterns.txt * as it would prefix each line with the filename and also include an occasional -- – steve Jul 19 '15 at 21:55
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The following will search all not-dot files in the current directory:

sed '/string/{
        $!N;$!N;$!N;$!N
        w ./new_out_file
     }' ./*

To do multiple -Fixed-string matches with grep -A w/o find and w/o the filenames prepended to each match, you just first need a single stream.

cat ./* | grep -A2 -Ff pattern_file >outfile
mikeserv
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  • Thanks ... but if i have list of names to searched in files of a directory and need same 4 lines from its occurrence to copied to output. How it gonna help ?? – Praveen Kashekar Jul 19 '15 at 16:41
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    @PraveenKashekar I don't know what this means. This is an answer to the question you asked. – mikeserv Jul 19 '15 at 16:50
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I got solution for it:

grep -A 2 -f 'INPUT.txt' *.* >> RESULT.txt
chaos
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Praveen Kashekar
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    That prepends the filename in which each match is found to the matched lines. That's nothing like what is requested in your question. – mikeserv Jul 21 '15 at 17:29