bin/live-swapfile

   1 #!/bin/sh
   2
   3 # File: live-swapfile - create and use a swap file
   4 # Copyright: (C) 2009 Daniel Baumann <mail@daniel-baumann.ch>
   5 # License: GPL-3+
   6
   7 set -e
   8
   9 # Options
  10 _SWAP_DIRECTORY="${_SWAP_DIRECTORY:-/live/swap}"
  11 _SWAP_FILE="${_SWAP_FILE:-swapfile.img}"
  12
  13 _SWAP_SIZE="${_SWAP_SIZE:-auto}"
  14 _SWAP_FACTOR="${_SWAP_FACTOR:-2}"
  15
  16 _SWAP_PURGE="${_SWAP_PURGE:-true}"
  17 _FORCE="${_FORCE:-true}"
  18
  19 case "${1}" in
  20         add)
  21                 # Reading size of physical memory
  22                 _MEM_TOTAL_KB="$(awk '/^MemTotal: / { print $2 }' /proc/meminfo)"
  23                 _MEM_TOTAL_MB="$(expr ${_MEM_TOTAL_KB} / 1024)"
  24
  25                 echo "Found ${_MEM_TOTAL_MB} MB physical memory."
  26
  27                 # Setting size of new swapfile
  28                 if [ -z "${_SWAP_SIZE}" ] || [ "${_SWAP_SIZE}" = "auto" ]
  29                 then
  30                         _SWAP_SIZE_KB="$(expr ${_MEM_TOTAL_KB} '*' ${_SWAP_FACTOR})"
  31                         _SWAP_SIZE_MB="$(expr ${_SWAP_SIZE_KB} / 1024)"
  32                 else
  33                         _SWAP_SIZE_MB="${_SWAP_SIZE}"
  34                 fi
  35
  36                 echo "Requesting ${_SWAP_SIZE_MB} MB swapfile."
  37
  38                 # Reading size of old swapfile
  39                 if [ -e "${_SWAP_DIRECTORY}/${_SWAP_FILE}" ]
  40                 then
  41                         _SWAP_FILESIZE="$(ls -hl ${_SWAP_DIRECTORY}/${_SWAP_FILE} | awk '{ print $5 }')"
  42
  43                         echo "Found ${_SWAP_FILESIZE} MB swapfile."
  44                 fi
  45
  46                 # Creating new swap file
  47                 if [ "${_SWAP_FILESIZE}" != "${_SWAP_SIZE_MB}M" ]
  48                 then
  49                         if [ "${_FORCE}" = "true" ]
  50                         then
  51                                 # Removing old swapfile
  52                                 rm -f "${_SWAP_DIRECTORY}/${_SWAP_FILE}"
  53
  54                                 echo "Creating ${_SWAP_SIZE_MB} MB swapfile."
  55
  56                                 mkdir -p "${_SWAP_DIRECTORY}"
  57
  58                                 # Unfortunately, swapon does not support files
  59                                 # with holes, therefore we cannot preallocate.
  60                                 dd if=/dev/zero of="${_SWAP_DIRECTORY}/${_SWAP_FILE}"  bs=1024k count="${_SWAP_SIZE_MB}"
  61                         else
  62                                 echo "Exit."
  63                                 return 1
  64                         fi
  65                 fi
  66
  67                 echo "Enabling ${_SWAP_DIRECTORY}/${_SWAP_FILE}."
  68
  69                 mkswap "${_SWAP_DIRECTORY}/${_SWAP_FILE}"
  70                 swapon "${_SWAP_DIRECTORY}/${_SWAP_FILE}"
  71                 ;;
  72
  73         rm|remove)
  74                 if grep -qs "${_SWAP_DIRECTORY}/${_SWAP_FILE}" /proc/swaps
  75                 then
  76                         echo "Disabling ${_SWAP_DIRECTORY}/${_SWAP_FILE}."
  77
  78                         swapoff "${_SWAP_DIRECTORY}/${_SWAP_FILE}"
  79                 fi
  80
  81                 if [ "${_SWAP_PURGE}" = "true" ]
  82                 then
  83                         echo "Removing ${_SWAP_DIRECTORY}/${_SWAP_FILE}."
  84
  85                         rm -f "${_SWAP_DIRECTORY}/${_SWAP_FILE}"
  86
  87                         __DIRECTORY="${_SWAP_DIRECTORY}"
  88                         while [ "${__DIRECTORY}" != "/" ]
  89                         do
  90                                 rmdir --ignore-fail-on-non-empty "${__DIRECTORY}"
  91                                 __DIRECTORY="$(dirname ${__DIRECTORY})"
  92                         done
  93                 fi
  94                 ;;
  95
  96         *)
  97                 echo "Usage: ${0} {add|remove}"
  98                 exit 1
  99                 ;;
 100 esac