mkinitrd.sh

   1 #!/bin/sh
   2 #
   3 # mkinitrd.sh: Shell script to make an initial initrd image
   4 # by Jose V Beneyto, sepen at crux dot nu
   5
   6 msgUsage() {
   7   echo "Usage: $APPNAME <options>"
   8   echo "Where options are:"
   9   echo "  --name=NAME   Name for the result image (default: initrd.gz)"
  10   echo "  --size=SIZE   Size expecified in bytes (default: 4096)"
  11   echo "  --type=TYPE   Filesystem type for the image (default: ext2)"
  12   echo "Example:"
  13   echo "  $APPNAME --name=myinitrd.gz --size=8192"
  14   exit 0
  15 }
  16
  17 msgError() {
  18   echo "Error, $@" 2>&1
  19   exit 1
  20 }
  21
  22 checkRoot() {
  23   [ "$(id -u)" != "0" ] && msgError "you need to be root to do this."
  24 }
  25
  26 parseArgs() {
  27   [ $# -lt 1 ] && msgUsage
  28   for arg in $@; do
  29     case $arg in
  30       --name=*) IMG_NAME=${arg##*=} ;;
  31       --size=*) IMG_SIZE=${arg##*=} ;;
  32       --type=*) IMG_TYPE=${arg##*=} ;;
  33       *) msgUsage ;;
  34     esac
  35   done
  36 }
  37
  38 main() {
  39   rm -rf $TMP_PATH $MNT_PATH
  40   install -d $TMP_PATH $MNT_PATH
  41   pushd $TMP_PATH && \
  42   rm -f initrd
  43   dd if=/dev/zero of=initrd bs=1024 count=$IMG_SIZE && \
  44   mkfs.$IMG_TYPE -F -m 0 -b 1024 initrd $IMG_SIZE && \
  45   mount -v -o loop -t $IMG_TYPE initrd $MNT_PATH && \
  46   rm -rf $MNT_PATH/lost+found && \
  47   install -d -m 0755 $MNT_PATH/{mnt,media,etc,dev,sys,proc,lib,usr,var/{log,lock,run},tmp} && \
  48   mknod $MNT_PATH/dev/console c 5 1 && chmod 666 $MNT_PATH/dev/console && \
  49   mknod $MNT_PATH/dev/null c 1 3 && chmod 666 $MNT_PATH/dev/null && \
  50   mknod $MNT_PATH/dev/tty c 5 0 && chmod 666 $MNT_PATH/dev/tty && \
  51   mkdir $MNT_PATH/dev/rd && mknod $MNT_PATH/dev/rd/0 b 1 0
  52   mknod $MNT_PATH/dev/ram0 b 1 0 && chmod 600 $MNT_PATH/dev/ram0
  53   for i in 0 1 2 3 4 5 6 7; do
  54     mknod $MNT_PATH/dev/tty$i c 4 $i && chmod 666 $MNT_PATH/dev/tty$i
  55   done && \
  56   umount -v $MNT_PATH && \
  57   gzip -v initrd && \
  58   popd && \
  59   mv $TMP_PATH/initrd.gz $IMG_NAME
  60 }
  61
  62 APPNAME="$(basename $0)"
  63
  64 TMP_PATH="$(cd $(dirname $APPNAME); pwd)/.tmp"
  65 MNT_PATH="$(cd $(dirname $APPNAME); pwd)/.mnt"
  66
  67 IMG_SIZE=4096       # default image size = 4MB
  68 IMG_TYPE=ext2       # default filesystem type = ext2
  69
  70 export PATH=$PATH:/sbin:/usr/sbin
  71
  72 checkRoot
  73 parseArgs $@ && \
  74 main || msgError "$APPNAME failed"
  75
  76 umount -v $MNT_PATH
  77 rm -rf $TMP_PATH $MNT_PATH
  78
  79 # End of file