210 lines
6.5 KiB
Bash
210 lines
6.5 KiB
Bash
#!/bin/bash
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# SPDX-Version: 3.0
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# SPDX-CreationInfo: 2025-10-11; WEIDNER, Marc S.; <msw@coresecret.dev>
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# SPDX-ExternalRef: GIT https://git.coresecret.dev/msw/CISS.debian.live.builder.git
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# SPDX-FileContributor: WEIDNER, Marc S.; Centurion Intelligence Consulting Agency
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# SPDX-FileCopyrightText: 2024-2025; WEIDNER, Marc S.; <msw@coresecret.dev>
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# SPDX-FileType: SOURCE
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# SPDX-License-Identifier: EUPL-1.2 OR LicenseRef-CCLA-1.0
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# SPDX-LicenseComment: This file is part of the CISS.debian.installer.secure framework.
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# SPDX-PackageName: CISS.debian.live.builder
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# SPDX-Security-Contact: security@coresecret.eu
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set -Ceuo pipefail
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printf "\e[95m++++ ++++ ++++ ++++ ++++ ++++ ++ 🧪 '%s' starting ... \e[0m\n" "${0}"
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[[ -r /root/ciss_xdg_tmp.sh ]] && . /root/ciss_xdg_tmp.sh
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export DEBIAN_FRONTEND="noninteractive" INITRD="No"
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apt-get install -y --no-install-recommends kexec-tools busybox-static
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install -d -m 0755 /boot/ciss-memwipe
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install -d -m 0755 /usr/local/sbin
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install -d -m 0755 /etc/systemd/system
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install -d -m 0755 /etc/default
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### Pick a kernel to kexec into: use the latest installed vmlinuz. -------------------------------------------------------------
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# shellcheck disable=SC2012,SC2155
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declare _kernel="$(cd /boot && ls -1 vmlinuz-* | sed 's|vmlinuz-||' | sort -V | tail -n1)"
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cp -f "/boot/vmlinuz-${_kernel}" /boot/ciss-memwipe/vmlinuz
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### Build minimal initramfs with a busybox and a tiny '/init'. -----------------------------------------------------------------
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declare TMPDIR; TMPDIR="$(mktemp -d)"
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trap 'rm -rf "${TMPDIR}"' EXIT
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mkdir -p "${TMPDIR}"/{bin,dev,proc,sys,wipe}
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cp -f /bin/busybox.static "${TMPDIR}/bin/busybox"
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cat << 'EOF' >| "${TMPDIR}/init"
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#!/bin/busybox sh
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### Minimal init to wipe RAM, then power off.
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### Parses cmdline: ciss_wipe_passes=2 ciss_wipe_mode=zero+random ciss_dd_bs=64M ciss_tmpfs_pct=95
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set -eu
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get_arg() { # $1=key ; echoes value or empty
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for tok in $(cat /proc/cmdline); do
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case "${tok}" in
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$1=*) echo "${tok#*=}"; return 0;;
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esac
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done
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echo ""
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}
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mount -t devtmpfs devtmpfs /dev 2>/dev/null || true
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[ -e /dev/console ] || mknod -m 600 /dev/console c 5 1
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[ -e /dev/null ] || mknod -m 666 /dev/null c 1 3
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[ -e /dev/urandom ] || mknod -m 444 /dev/urandom c 1 9
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mount -t proc proc /proc
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mount -t sysfs sysfs /sys
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PASSES="$(get_arg ciss_wipe_passes)"; [ -n "${PASSES}" ] || PASSES=2
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MODE="$(get_arg ciss_wipe_mode)"; [ -n "${MODE}" ] || MODE="zero+random"
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BS="$(get_arg ciss_dd_bs)"; [ -n "${BS}" ] || BS=64M
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PCT="$(get_arg ciss_tmpfs_pct)"; [ -n "${PCT}" ] || PCT=95
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echo 1 > /proc/sys/kernel/printk 2>/dev/null || true
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MEM_KB="$(awk '/MemTotal:/ {print $2}' /proc/meminfo)"
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SIZE_KB=$(( MEM_KB * PCT / 100 ))
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mount -t tmpfs -o "size=${SIZE_KB}k,nodev,nosuid,noexec,mode=0700" tmpfs /wipe
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wipe_pass() {
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pattern="$1"
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if [ "${pattern}" = "zero" ]; then
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src="/dev/zero"
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else
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src="/dev/urandom"
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fi
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i=0
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while :; do
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busybox dd if="${src}" of="/wipe/block_${i}" bs="${BS}" status=none || break
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i=$((i+1))
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done
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sync
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echo 3 > /proc/sys/vm/drop_caches 2>/dev/null || true
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rm -f /wipe/block_* 2>/dev/null || true
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sync
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}
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DO_ZERO=0; DO_RANDOM=0
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case "${MODE}" in
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zero) DO_ZERO=1 ;;
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random) DO_RANDOM=1 ;;
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zero+random|random+zero) DO_ZERO=1; DO_RANDOM=1 ;;
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*) DO_ZERO=1 ;;
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esac
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p=1
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while [ ${p} -le "${PASSES}" ]; do
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[ ${DO_ZERO} -eq 1 ] && wipe_pass zero
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[ ${DO_RANDOM} -eq 1 ] && wipe_pass random
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p=$((p+1))
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done
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sync
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busybox poweroff -f || echo o >| /proc/sysrq-trigger
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EOF
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chmod +x "${TMPDIR}/init"
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( cd "${TMPDIR}" && find . -print0 | cpio --null -ov --format=newc ) | gzip -9 > /boot/ciss-memwipe/initrd.img
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cat << 'EOF' >| /etc/default/ciss-memwipe
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### CISS Memory Wipe defaults
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CISS_WIPE_PASSES=2 # number of passes
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CISS_WIPE_MODE="zero+random" # zero | random | zero+random
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CISS_WIPE_DD_BS="64M" # dd block size
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CISS_WIPE_TMPFS_PCT=95 # percentage of MemTotal to allocate
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EOF
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cat << 'EOF' >| /usr/local/sbin/ciss-memwipe
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#!/bin/bash
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# Prepare and execute kexec-based memory wipe.
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set -euo pipefail
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. /etc/default/ciss-memwipe || true
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KERNEL="/boot/ciss-memwipe/vmlinuz"
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INITRD="/boot/ciss-memwipe/initrd.img"
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append_common="quiet loglevel=1 ciss_wipe_passes=${CISS_WIPE_PASSES:-2} ciss_wipe_mode=${CISS_WIPE_MODE:-zero+random} ciss_dd_bs=${CISS_WIPE_DD_BS:-64M} ciss_tmpfs_pct=${CISS_WIPE_TMPFS_PCT:-95}"
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prepare() {
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# Try to allow kexec if not locked down
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if [ -w /proc/sys/kernel/kexec_load_disabled ] && [ "$(cat /proc/sys/kernel/kexec_load_disabled)" = "1" ]; then
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echo 0 > /proc/sys/kernel/kexec_load_disabled || true
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fi
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# Load wipe kernel
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if command -v kexec >/dev/null 2>&1 && [ -s "${KERNEL}" ] && [ -s "${INITRD}" ]; then
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kexec -l "${KERNEL}" --initrd="${INITRD}" --append="${append_common}" || true
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fi
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}
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fallback_inplace() {
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# Last-resort: wipe in-place via tmpfs and then power off
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mount -t tmpfs -o "size=95%,nodev,nosuid,noexec,mode=0700" tmpfs /run/wipe 2>/dev/null || mkdir -p /run/wipe
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i=0
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while :; do
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dd if=/dev/zero of="/run/wipe/blk_${i}" bs="${CISS_WIPE_DD_BS:-64M}" status=none || break
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i=$((i+1))
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done
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sync; echo 3 > /proc/sys/vm/drop_caches 2>/dev/null || true
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rm -f /run/wipe/blk_* 2>/dev/null || true
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sync
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systemctl poweroff -f || poweroff -f || echo o > /proc/sysrq-trigger
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}
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execute() {
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sync; echo 3 > /proc/sys/vm/drop_caches 2>/dev/null || true
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# Prefer systemd's path if possible
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if command -v systemctl >/dev/null 2>&1 && systemctl --quiet is-system-running; then
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# If kexec image was loaded, systemctl kexec will use it
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systemctl kexec || kexec -e || fallback_inplace
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else
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kexec -e || fallback_inplace
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fi
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}
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case "${1:-}" in
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prepare) prepare ;;
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execute) execute ;;
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*) echo "Usage: $0 {prepare|execute}" >&2; exit 2 ;;
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esac
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EOF
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chmod 0755 /usr/local/sbin/ciss-memwipe
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### Systemd service: load at boot, execute on shutdown
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cat << 'EOF' >| /etc/systemd/system/ciss-memwipe.service
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[Unit]
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Description=CISS: preload and execute kexec-based RAM wipe on shutdown
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DefaultDependencies=no
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# Ensure we run late enough on shutdown, but early enough to take over
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Before=shutdown.target
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After=local-fs.target network.target multi-user.target
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[Service]
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Type=oneshot
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RemainAfterExit=yes
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ExecStart=/usr/local/sbin/ciss-memwipe prepare
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# ExecStop runs during shutdown: jump into wipe kernel
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ExecStop=/usr/local/sbin/ciss-memwipe execute
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TimeoutStartSec=20s
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TimeoutStopSec=infinity
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[Install]
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WantedBy=multi-user.target
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EOF
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systemctl enable ciss-memwipe.service
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printf "\e[92m++++ ++++ ++++ ++++ ++++ ++++ ++ ✅ '%s' applied successfully. \e[0m\n" "${0}"
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exit 0
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# vim: number et ts=2 sw=2 sts=2 ai tw=128 ft=sh
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