lif: get the specified line of a file, optionally surrounded by lines of context copy to a directory in your $PATH (I'd suggest ~/bin), chmod +x, and have fun `lif -h` for help

lif

#!/bin/bash

context=0

usage() {
	cat <<EOF
lif: Line in File

Usage:
lif [-c context] line [file]
or
lif [-c context] [file] line
or
echo "some unix pipe" | lif [-c context] line

lif will print the line in file (or stdin) at the specified line number, surrounded by the specified amount of context

EOF
exit 0
}

while getopts "hc:" OPTION
do
	case $OPTION in
		c)
			context=$OPTARG
			;;
		h)
			usage
			;;
	esac
done

#normalize the input
shift $(($OPTIND - 1))

if [ -t 0 ] 
then
	# terminal
	if [ $# -lt 2 ]
	then
		usage
	fi
	if [ -a $1 ]
	then
		file=$1
		line=$2
	else
		file=$2
		line=$1
	fi
	headLen=$(($line+$context))
	tailLen=$((2*$context+1))
	head -$headLen $file | tail -$tailLen
else
	# pipe
	if [ $# -ne 1 ]
	then
		usage
	fi
	lineNum=1
	startLine=$(($1-$context))
	endLine=$(($1+$context))
	while read line
	do
		if [ $lineNum -ge $startLine ]
		then
			echo $line
		fi
		if [ $lineNum -ge $endLine ]
		then
			break;
		fi
		lineNum=$(($lineNum+1))
	done
fi