Find file in current directory recursively, and print lines which match PATTERN.

file_finder.sh

#!/bin/bash

usage()
{
        # Fetch the shell script name
        local script_name=$(basename "$0")

        # Show help
        cat << END

Usage: $script_name PATTERN [PATH] [NAME_PATTERN]
Find file in current directory recursively, and print lines which match PATTERN.

        PATH    find file in PATH directory, instad of current directory
        NAME_PATTERN    specify name pattern to find file

Examples:
        $script_name return
        $script_name return ~'*.txt'

END
}

# If failts to fetch any arguments
if [ "$#" -eq 0 ]; then
        usage
        exit 1
fi

pattern=$1
directory=$2
name=$3

# If 2nd argument is empy, set currenty directory
if [ -z "$directory" ]; then
        directory='.'
fi

# If 3rd argument is empy, set '*'
if [ -z "$name" ]; then
        name='*'
fi

# If the directory you specified is nowhere, comes out the error, and exit
if [ ! -d "$directory" ]; then
        echo "$0: ${directory}: No such directory" 1>&2
        exit 2
fi

find "$directory" -type f -name "$name" | xargs grep -nH "$pattern"