shell script Grep -f in for loop

Question

need help for grep -f to run in for loop

basically for each entry in name.txt, I want to grep all the line(s) from A.txt and write out for in separate files

For example 1) name.txt is a list of three following names

America
Europe   
Asia

2) A.txt is(tab delimited)

X y Z America
x a b Asia
y b c America
a b c Europe
x y z Europe
a b c America

now taking each entry from name.txt file, search the corresponding line(s) in A.txt and return in three separate output files:

file1: X y Z America
       y b c America
       a b c America

file2: a b c Europe
       x y z Europe
file3: x a b Asia

may be writing it in script and execute with bash?

Thanks in advance!!!

Kamal · Accepted Answer · 2012-08-10 20:19:54Z

2

Run the following script (as ./script.sh name.txt input.txt) where name.txt has the names and input.txt is your input file. the output files are saved as file_America.txt, file_Asia.txt and file_Europe.txt

#!/bin/bash -x

while read line; do
#skip empty line
[ -z "$line" ] && continue;
#run grep and save the output
grep "$line" "$2" > file_$line.txt;
done < "$1"

edited Aug 10, 2012 at 20:19

answered Aug 10, 2012 at 18:42

Kamal

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2 Comments

chepner Over a year ago

Useless use of cat. Use input redirection: while read line; do ...; done < "$1"

Keith Thompson Over a year ago

@chepner: Or < $1 while read line; do ...; done. Yes, the redirection can go before the command, and in this case it makes it clearer.

Birei · Accepted Answer · 2012-08-10 19:38:55Z

0

One way using awk:

awk '
    ## Process first file of arguments. Save data in an array, the name as
    ## key, and the number of the output file to write as value.
    FNR == NR {
        name[ $1 ] = FNR;
        next;
    }

    ## Process second file of arguments. Check last field of the line in the 
    ## array and print to file matched by the value.
    FNR < NR {
        print $0 > sprintf( "%s%d", "file", name[ $NF ] );
    }
' name.txt A.txt

Check output files:

head file[123]

With following result:

==> file1 <==
X y Z America
y b c America
a b c America

==> file2 <==
a b c Europe
x y z Europe

==> file3 <==
x a b Asia

answered Aug 10, 2012 at 19:38

Birei

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