swap-fix

#!/bin/bash
#
# swap-fix - fix references of swap partition in fstab, initramfs, etc
#
#    Copyright (C) 2013 Rodrigo Silva (MestreLion) <linux@rodrigosilva.com>
#
#    This program is free software: you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation, either version 3 of the License, or
#    (at your option) any later version.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with this program. See <http://www.gnu.org/licenses/gpl.html>

label=SWAP
fstab=/etc/fstab
resume=/etc/initramfs-tools/conf.d/resume

myname="${0##*/}"
verbose=1

fatal()   { [[ "$1" ]] && echo "$myname: error: $1" >&2 ; exit ${2:-1} ; }
message() { ((verbose)) && printf "%s\n" "$1"; }
argerr()  { printf "%s: %s\n" "$myname" "${1:-error}" >&2 ; usage 1 ; }
missing() { argerr "missing ${2:+$2 }argument${1:+ from $1}." ; }
invalid() { argerr "invalid option: $1" ; }

usage() {
	cat <<-USAGE
	Usage: $myname [options]
	USAGE
	if [[ "$1" ]] ; then
		cat >&2 <<- USAGE
		Try '$myname --help' for more information.
		USAGE
		exit 1
	fi
	cat <<-USAGE

	Add a $swaplabel label to your swap partition, and updates references
	in $fstab and $resume to use LABEL instead of UUID.

	Both files are only modified if necessary. $fstab is backed up prior
	to edit, and $resume is created if it does not exist.

	Refuses to run if none or multiple swap partitions are found on the
	system. Multiple swap entries in $fstab are removed.

	Options:
	  -h|--help     - show this page.
	  -q|--quiet    - supress informative messages, only output errors.

	  --label LABEL - set swap partition label to LABEL (default $label)

	Copyright (C) 2013 Rodrigo Silva (MestreLion) <linux@rodrigosilva.com>
	License: GPLv3 or later. See <http://www.gnu.org/licenses/gpl.html>
	USAGE
	exit 0
}

# Option handling
files=()
for arg in "$@"; do [[ "$arg" == "-h" || "$arg" == "--help" ]] && usage ; done
while (( $# )); do
	case "$1" in
	-q|--quiet    ) verbose=1                      ;;
	--label=*     ) label="${1#*=}"                ;;
	--label       ) shift ; label="$1"             ;;
	*             ) invalid "$1"                   ;;
	esac
	shift
done

[[ "$(id -u)" -eq 0 ]] || fatal "$myname must be run as root"

[[ "$label" ]] || missing "--label" "LABEL"

uuid=( $(blkid -t TYPE=swap -s UUID -o value) )

(( "${#uuid[@]}" < 1 )) && fatal "no swap partitions found. Use 'mkswap' to create one"
(( "${#uuid[@]}" > 1 )) && fatal "multiple swap partitions found, too complex for me"

dev=$(blkid -U "$uuid")
devlabel=$(swaplabel "$dev" | grep 'LABEL:' | cut -d' ' -f2)

message "Found swap partition: $dev (UUID=$uuid${devlabel:+, label=$devlabel})"

if [[ "$devlabel" != "$label" ]]; then
	message "Labeling swap partition $label"
	swaplabel --label "$label" "$dev"
fi

if [[ $(awk -v label="$label" '$3 == "swap" && $1 ~ "^LABEL=" label "$" {print}' "$fstab") ]]; then
	message "no changes necessary in $fstab"
elif [[ -z $(awk '$3 == "swap" && $1 !~ /^#/{print}' "$fstab") ]]; then
	message "updating $fstab, adding reference to swap"
	cp "$fstab"{,.swapfix.bak}
	echo "LABEL=$label none swap sw 0 0" >> "$fstab"
else
	message "updating $fstab, replacing swap reference to LABEL=$label"
	cp "$fstab"{,.swapfix.bak}
	awk -v label="$label" \
		'$3 == "swap" && $1 !~ /^#/ {
			if (swap) next
			swap=1
			len=length($1)-1
			sub($1, sprintf("%*s", -len, "LABEL=" label))
		} 1' "$fstab".swapfix.bak > "$fstab"
fi

if [[ -f "$resume" ]] && grep -q "^RESUME=LABEL=$label" "$resume"; then
	message "no changes necessary in $resume"
else
	message "updating $resume"
	echo "RESUME=LABEL=$label" > "$resume"
fi

swapon -a