How to search for a pattern between lines 1500 to 2500?

Question

I have 8 files, and each contains around 2000 lines. I want to search the particular word in these files between line number 1500 to 2500.

The output should look like:

sample_1.txt :

1510:declare var testing


sample_2.txt :

1610:declare var testing


sample_7.txt :

1610:declare var testing


sample_10.txt :

1710:declare var testing

Is it possible to use grep for this task?

Answer 1

Try this:

#!/usr/bin/awk -f
BEGIN {
    begin = ARGV[1]
    end = ARGV[2]
    pattern=ARGV[3]
    ARGV[1] = ARGV[2] = ARGV[3] = ""
}

NR > end {exit}

NR == 1 {
    print FILENAME " :\n"
}

NR >= begin {
    if ($0 ~ pattern) 
        print NR ":" $0
}

Call it like this:

./rangegrep 1500 2000 'declare var testing' sample*.txt

The search string can be a regular expression.

Edit:

I changed from range checking the line number to using exit as in akira's answer since the exit will stop processing lines at the end of the range and save time by not reading the rest of the lines in the file.

Answer 2

awk does what you want:

% awk 'NR < 1500 { next }; NR > 2500 { exit}; \
    /pattern/ { printf("%s:\n%d:%s\n", FILENAME, NR, $0); }' \
    sample_*.txt

to have as much space as you provided in your desired output, you just have to add as many \n to the printf statement...

Answer 3

Without using awk how about some shell script + sed:

for f in sample_*.txt ; do echo "$f : " ; \
    sed -ne '1500,2500{/pattern/{=;p}}' $f ; \
    echo ; \
done

Answer 4

Purely In The Interests Of Science, I present an implementation of torso, the logical middle between head and tail.

In practice, as others have noted, this is really unnecessary since you can get the desired output yourself by a trivial combination of head and tail.

#!/bin/sh

usage () {
    printf "$0: $0 [-c <byte> -C <byte>] [-n <line> -N <line>] file [file ... ]\n"
}

while [ $# -gt 0 ] ; do
    case "$1" in
            -c|--byte-start) shift ; start="$1" ; mode=byte ; shift ;;
            -C|--byte-end) shift ; end="$1" ; mode=byte ; shift ;;
            -n|--line-start) shift ; start="$1" ; mode=line ; shift ;;
            -N|--line-end) shift ; end="$1" ; mode=line ; shift ;;
                --) shift ;;
            -*) printf "bad option '%s'\n" "$1" ; usage ; exit 201 ;;
                *) files=("${files[@]}" "$1") ; shift ;;
         esac
done

if [ $start -gt $end ] ; then
    printf "end point cannot be before start point\n"
    usage
    exit 202
fi

head_cmd=
tail_cmd=
end=$((end - start))
if [ $mode = "line" ] ; then
    head_cmd="-n $end"
    tail_cmd="-n +$start"
elif [ $mode = "byte" ] ; then
    head_cmd="-c $end"
    tail_cmd="-c +$start"
fi

if [ ${#files[@]} -eq 0 ] ; then
    cat - | tail $tail_cmd | head $head_cmd
else
    tail $tail_cmd "${files[@]}" | head $head_cmd
fi

To keep it topical, here's how to use torso to solve the question:

torso -n 1500 -N 2500 input_file | grep -n "test"

Or for output conforming to the requirements

for file in sample_{1,2,7,10} ; do
     printf "\n\n%s:\n\n" "$file"
     torso -n 1500 -N 2500 "$file" | grep -n "test"
done

You may begin your criticisms... now!