Advanced Bash−Scripting Guide

Advanced Bash−Scripting Guide
Example 13−6. Creating a filesystem in a file
SIZE=1000000 # 1 meg
head −c $SIZE < /dev/zero > file # Set up file of designated size.
losetup /dev/loop0 file
# Set it up as loopback device.
mke2fs /dev/loop0
# Create filesystem.
mount −o loop /dev/loop0 /mnt # Mount it.
# Thanks, S.C.
mkswap
Creates a swap partition or file. The swap area must subsequently be enabled with swapon.
swapon, swapoff
Enable / disable swap partitition or file. These commands usually take effect at bootup and shutdown.
mke2fs
Create a Linux ext2 filesystem. This command must be invoked as root.
Example 13−7. Adding a new hard drive
#!/bin/bash
# Adding a second hard drive to system.
# Software configuration. Assumes hardware already mounted.
# From an article by the author of this document.
# in issue #38 of "Linux Gazette", http://www.linuxgazette.com.
ROOT_UID=0
E_NOTROOT=67
# This script must be run as root.
# Non−root exit error.
if [ "$UID" −ne "$ROOT_UID" ]
then
echo "Must be root to run this script."
exit $E_NOTROOT
fi
# Use with extreme caution!
# If something goes wrong, you may wipe out your current filesystem.
NEWDISK=/dev/hdb
# Assumes /dev/hdb vacant. Check!
MOUNTPOINT=/mnt/newdisk # Or choose another mount point.
fdisk $NEWDISK
mke2fs −cv $NEWDISK1 # Check for bad blocks & verbose output.
# Note: /dev/hdb1, *not* /dev/hdb!
mkdir $MOUNTPOINT
chmod 777 $MOUNTPOINT # Makes new drive accessible to all users.
# Now, test...
# mount −t ext2 /dev/hdb1 /mnt/newdisk
# Try creating a directory.
# If it works, umount it, and proceed.
# Final step:
# Add the following line to /etc/fstab.
# /dev/hdb1 /mnt/newdisk ext2 defaults 1 1
Chapter 13. System and Administrative Commands 229