replace

#!/usr/bin/env bash
# author: andreasl

function show_help {
    script_name="${0##*/}"

    msg="${script_name}\n"
    msg+="Replace strings in files in a directory tree."
    msg+="Grep a given pattern on files with given file masks below the cwd and replace it with a"
    msg+=" given string after asking for confirmation.\n"
    msg+="\n"
    msg+="Usage:\n"
    msg+="  ${script_name} <search-pattern> <replace-string> <file-pattern>...\n"
    msg+="\n"
    msg+="Examples:\n"
    msg+="  ${script_name} 'echo' 'printf' *.sh            # replace 'echo' with 'printf' in all *.sh files below the cwd\n"
    msg+="  ${script_name} '2018' '2019' *.txt *.md        # replace '2018' with '2019' in all *.txt and *.md files below the cwd\n"
    msg+="  ${script_name} 'wind|rain' sun vacation.txt    # replace all matching text passages with 'sun' in files called \"vacation.txt\"\n"
    msg+="  ${script_name} -h                              # print the usage message\n"
    msg+="  ${script_name} --help                          # print the usage message\n"
    printf "$msg"
}

if [[ "$1" =~ ^(-h|--help)$ ]]; then
    show_help
    exit 1
elif [ "$#" -lt 3 ]; then
    printf 'Usage:\n'
    printf -- "  ${0##*/} -h|--help\n"
    printf -- "  ${0##*/} <search-pattern> <replace-string> <file-pattern>...\n"
    exit 1
fi

pattern_to_look_for="$1"
shift
string_to_replace_with="$1"
shift

found_any_matches=false
for file_pattern in "$@"; do
    # preview
    if grep -HRn --color --include "$file_pattern" "$pattern_to_look_for" .; then
        found_any_matches=true
    fi
done
if [ "$found_any_matches" != true ]; then
    printf 'Found no matches.\n'
    exit 2
fi

read -r -e -n1 -p 'Do you want to continue? (y)es, (n)o, (i)nteractive: ' yes_no_i
if [[ "$yes_no_i" == [iI] ]]; then
    interactive=true
elif [[ "$yes_no_i" != [yY] ]]; then
    exit 0
fi

b='\e[1m'
n='\e[m'

files=()
for file_pattern in "$@"; do
    files_lines="$(grep -Rl --include "$file_pattern" "$pattern_to_look_for" .)"
    while IFS= read -r line; do
        files+=("$line")
    done <<<"$files_lines"
done

for file in "${files[@]}"; do
    # do replace
    if [ "$interactive" == true ]; then
        printf "Change occurences in ${b}${file}${n}? (y)es, (n)o, (s)how: "
        read -r -e -n1 yes_no_show
        if [[ "$yes_no_show" == [sS] ]]; then
            grep -Hn --color "$pattern_to_look_for" "$file"
            printf "Change occurences in ${b}${file}${n}? [yY/nN]: "
            read -r -e -n1 yes_no
            if [[ "$yes_no" != [yY] ]]; then
                continue
            fi
        elif [[ "$yes_no_show" != [yY] ]]; then
            continue
        fi
    fi

    sed --follow-symlinks -i "s@${pattern_to_look_for}@${string_to_replace_with}@g" "$file" # GNU
    #sed -i '' "s@${pattern_to_look_for}@${string_to_replace_with}@g" "$file"  # Mac BSD sed
    grep -FHn --color --include "$file_pattern" "$string_to_replace_with" "$file"
done