source: bootscripts/lfs/init.d/mountvirtfs

#!/bin/sh
########################################################################
# Begin mountvirtfs
#
# Description : Ensure proc, sysfs, run, and dev are mounted
#
# Authors     : Gerard Beekmans - gerard@linuxfromscratch.org
#               DJ Lucas - dj@linuxfromscratch.org
# Update      : Bruce Dubbs - bdubbs@linuxfromscratch.org
#               Xi Ruoyao - xry111@xry111.site
#
# Version     : LFS 12.0
#
########################################################################

### BEGIN INIT INFO
# Provides:            mountvirtfs
# Required-Start:      $first
# Should-Start:
# Required-Stop:
# Should-Stop:
# Default-Start:       S
# Default-Stop:
# Short-Description:   Mounts various special fs needed at start
# Description:         Mounts /sys and /proc virtual (kernel) filesystems.
#                      Mounts /run (tmpfs) and /dev (devtmpfs).
#                      This is done only if they are not already mounted.
#                      with the kernel config proposed in the book, dev
#                      should be automatically mounted by the kernel.
# X-LFS-Provided-By:   LFS
### END INIT INFO

. /lib/lsb/init-functions

case "${1}" in
   start)
      # Make sure /run is available before logging any messages
      if ! mountpoint /run >/dev/null; then
         mount /run || failed=1
      fi

      mkdir -p   /run/lock 
      chmod 1777 /run/lock

      log_info_msg "Mounting virtual file systems: ${INFO}/run"

      if ! mountpoint /proc >/dev/null; then
         log_info_msg2 " ${INFO}/proc"
         mount -o nosuid,noexec,nodev /proc || failed=1
      fi

      if ! mountpoint /sys >/dev/null; then
         log_info_msg2 " ${INFO}/sys"
         mount -o nosuid,noexec,nodev /sys || failed=1
      fi

      if ! mountpoint /dev >/dev/null; then
         log_info_msg2 " ${INFO}/dev"
         mount -o mode=0755,nosuid /dev  || failed=1
      fi

      mkdir -p /dev/shm
      log_info_msg2 " ${INFO}/dev/shm"
      mount -o nosuid,nodev /dev/shm || failed=1

      mkdir -p /sys/fs/cgroup
      log_info_msg2 " ${INFO}/sys/fs/cgroup"
      mount -o nosuid,noexec,nodev /sys/fs/cgroup || failed=1

      (exit ${failed})
      evaluate_retval
      if [ "${failed}" = 1 ]; then
         exit 1
      fi

      log_info_msg "Create symlinks in /dev targeting /proc: ${INFO}/dev/stdin"
      ln -sf /proc/self/fd/0 /dev/stdin  || failed=1

      log_info_msg2 " ${INFO}/dev/stdout"
      ln -sf /proc/self/fd/1 /dev/stdout || failed=1

      log_info_msg2 " ${INFO}/dev/stderr"
      ln -sf /proc/self/fd/2 /dev/stderr || failed=1

      log_info_msg2 " ${INFO}/dev/fd"
      ln -sf /proc/self/fd   /dev/fd     || failed=1

      if [ -e /proc/kcore ]; then
         log_info_msg2 " ${INFO}/dev/core"
         ln -sf /proc/kcore  /dev/core   || failed=1
      fi

      (exit ${failed})
      evaluate_retval
      exit $failed
      ;;

   *)
      echo "Usage: ${0} {start}"
      exit 1
      ;;
esac

# End mountvirtfs