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#!/bin/bash
# Usage:
# grepl [OPTIONS] [GREP-OPTIONS] PATTERN FILE
help() {
cat <<EOF
Usage: grepl [OPTIONS] [GREP-OPTIONS] PATTERN FILE
Options:
-k, --length Specify the number of characters around the
searching keyword to be shown.
-H, --with-filename Display file names on each line.
--help Show this help message.
Please note that some grep options such as "-r" will break this script.
Specify FILE as a dash ("-") to read from stdin.
EOF
exit
}
# Postprocess the output: prepend file names if required.
postprocess() {
local show="$1"
local filename="$2"
if [ "$show" = true ]; then
sed -e "s|^|${filename}: |"
else
cat
fi
}
# How many characters around the searching keyword should be shown?
context_length=10
# Should file names be printed for each matched line?
show_file_names=false
while :
do
# Allow the length to be overridden on the command line by specifying -C=N.
case $1 in
--help)
help
;;
-k|--length)
context_length="$2"
shift 2
;;
-H|--with-filename)
show_file_names=true
shift
;;
*)
break
;;
esac
done
# What is the length of the control character for the color before and after the matching string?
# This is mostly determined by the environmental variable GREP_COLORS.
control_length_before=$(($(echo a | grep --color=always a | cut -d a -f '1' | wc -c)-1))
control_length_after=$(($(echo a | grep --color=always a | cut -d a -f '2' | wc -c)-1))
# The second last argument is the pattern.
pattern=${@: -2:1}
grep -E --color=always "$@" | \
grep --color=none -oE ".{0,$(($control_length_before + $context_length))}${pattern}.{0,$(($control_length_after + $context_length))}" | \
postprocess ${show_file_names} ${@: -1}
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