Bashでrm -rf *コマンドが実行される前に警告するプロンプトを実装する

$ tmpdird # 新規ディレクトリへ移動

$ ls
total 0
166351711236005864 drwxrwxrwx 1 yuis yuis 4096 Jul 10 21:59 ..
 23080948093026057 drwxrwxrwx 1 yuis yuis 4096 Jul 10 21:59 .

$ genfiles 3 # ファイルを生成

$ ls
total 0
166351711236005864 drwxrwxrwx 1 yuis yuis 4096 Jul 10 21:59 ..
  8444249304069546 -rwxrwxrwx 1 yuis yuis    2 Jul 10 21:59 3.txt
 23080948093026057 drwxrwxrwx 1 yuis yuis 4096 Jul 10 21:59 .
 51509920740553578 -rwxrwxrwx 1 yuis yuis    2 Jul 10 21:59 2.txt
 36310271996515302 -rwxrwxrwx 1 yuis yuis    2 Jul 10 21:59 1.txt

$ rm -rf * # 全ファイルを削除 > 確認プロンプト > n
W: It seems You are attempting to run kind of dangerous command. Continue? [y/n]
n

$ ls # ファイルが消されていないことを確認
total 0
166351711236005864 drwxrwxrwx 1 yuis yuis 4096 Jul 10 21:59 ..
  8444249304069546 -rwxrwxrwx 1 yuis yuis    2 Jul 10 21:59 3.txt
 23080948093026057 drwxrwxrwx 1 yuis yuis 4096 Jul 10 21:59 .
 51509920740553578 -rwxrwxrwx 1 yuis yuis    2 Jul 10 21:59 2.txt
 36310271996515302 -rwxrwxrwx 1 yuis yuis    2 Jul 10 21:59 1.txt

$ rm -rf * # 全ファイルを削除 > 確認プロンプト > y
W: It seems You are attempting to run kind of dangerous command. Continue? [y/n]
y

$ ls # ファイルが消されてることを確認
total 0
166351711236005864 drwxrwxrwx 1 yuis yuis 4096 Jul 10 21:59 ..
 23080948093026057 drwxrwxrwx 1 yuis yuis 4096 Jul 10 21:59 .

ok(){

  : <<< '
  yes or no prompt
  e.g. printf "The file alredy exist here. Override it? " ; ok && echo y || echo n
  '

  read -n 1 -r ; [[ $REPLY =~ ^[Yy]$ ]] && { echo ; return 0 ; } || { echo ; return 1 ; }

}

red=
\e[1;31m'
grn=
\e[1;32m'
yel=
\e[1;33m'
blu=
\e[1;34m'
mag=
\e[1;35m'
cyn=
\e[1;36m'
end=
\e[0m'

warn(){
  printf "${yel}W: ${*}\n${end}" >&2
}

##

shopt -s extdebug

preexec_invoke_exec () {
    [ -n "$COMP_LINE" ] && return  # do nothing if completing
    [ "$BASH_COMMAND" = "$PROMPT_COMMAND" ] && return # don't cause a preexec for $PROMPT_COMMAND
    local this_command=`HISTTIMEFORMAT= history 1 | sed -e "s/^[ ]*[0-9]*[ ]*//"`;

    # So that you don't get locked accidentally
    if [ "shopt -u extdebug" == "$this_command" ]; then
        return 0
    fi

        # // filtering

    # Modify $this_command and then execute it
    # eval "${this_command}"

    # echo "${this_command}"


    if [[ "${this_command}" =~ ^(somethingdangercommand$|somethingdangercommand[[:space:]]) ]]; then warn "It seems You are attempting to run kind of dangerous command. Continue? [y/n]" ; ok && eval "${this_command}" || return
  elif [[ "${this_command}" =~ ^(anotherSomethingdangercommand$|anotherSomethingdangercommand[[:space:]]) ]]; then warn "It seems You are attempting to run kind of dangerous command. Continue? [y/n]" ; ok && eval "${this_command}" || return
elif [[ "${this_command}" =~ ^(rm[[:space:]][-rf]{3}$|rm[[:space:]][-rf]{3}[[:space:]]) ]]; then warn "It seems You are attempting to run kind of dangerous command. Continue? [y/n]" ; ok && eval "${this_command}" || return
  else eval "${this_command}"
    fi

        # // filtering

    return 1 # This prevent executing of original command
}

trap 'preexec_invoke_exec' DEBUG

# disable/turn off history expansion `!` altogether
set +H