制作iso镜像(供yum源使用)


使用cp命令即可，# cp /dev/sr0 /data/centos6.iso  生成的镜像iso可以用来引导系统的

  查看内容iso内文件 # mount -t iso9660 /data/centos6.iso  /mnt/iso

  也可以使用# dd if=/dev/sr0 of=/data/centos6.iso 来生成iso镜像，同样可以用来引导系统



针对centos6 中将iso镜像分成两个，为了方便以后使用yum源时不缺包，可以将两个iso镜像合并

1.创建文件夹 mkdir /data/iso

2.将镜像中的所有文件拷贝至该目录下，对于相同的文件覆盖即可

3.使用mkisofs 来创建合集的iso镜像文件 

  #mkisofs -r -o centos6.iso  /data/iso


注意:使用mkisofs创建的合集iso镜像不能用来引导系统，只可作为yum源使用


若想要创建可以引导的合集iso镜像文件，可以使用mkdvdiso 来创建

http://wiki.centos.org 在该网站中搜索mkdvdiso ，mkdvdiso是用来创建引导iso镜像的shell脚本

给出准确网址:https://wiki.centos.org/zh/TipsAndTricks/DtoDVDMedia?highlight=%28mkdvdiso%29

mkdvdiso 脚本:


#!/bin/bash


# by Chris Kloiber <ckloiber@redhat.com>

# Mods under CentOS by Phil Schaffner <pschaff2@verizon.net>


# A quick hack that will create a bootable DVD iso of a Red Hat Linux

# Distribution. Feed it either a directory containing the downloaded

# iso files of a distribution, or point it at a directory containing

# the "RedHat", "isolinux", and "images" directories.


# This version only works with "isolinux" based Red Hat Linux versions.


# Lots of disk space required to work, 3X the distribution size at least.


# GPL version 2 applies. No warranties, yadda, yadda. Have fun.


# Modified to add sanity checks and fix CentOS4 syntax errors


# TODO:

#   Add checks for available disk space on devices holding output and

#       temp files.

#   Add optional 3rd parameter to specify location of temp directory.

#   Create .discinfo if not present.


OS_VER=\

$((test -e /etc/fedora-release && rpm -qf /etc/fedora-release --qf "FC%{VERSION}") \

|| (test -e /etc/redhat-release && rpm -qf /etc/redhat-release --qf "EL%{VERSION}") \

|| echo OS_unknown)


case "$OS_VER" in

  EL[45]*|FC?)

        IMPLANT=/usr/lib/anaconda-runtime/implantisomd5

        if [ ! -f $IMPLANT ]; then

            echo "Error: $IMPLANT Not Found!"

            echo "Please install anaconda-runtime and try again."

            exit 1

        fi

        ;;

  EL6*|FC1?)

        IMPLANT=/usr/bin/implantisomd5

        if [ ! -f $IMPLANT ]; then

            echo "Error: $IMPLANT Not Found!"

            echo "Please install isomd5sum and try again."

            exit 1

        fi

        ;;

  OS_unknown)

        echo "Unknown OS."

        exit 1

        ;;

  *)

        echo "Fix this script for $OS_VER"

        exit 1

esac


if [ $# -lt 2 ]; then

        echo "Usage: `basename $0` source /destination/DVD.iso"

        echo ""

        echo "        The 'source' can be either a directory containing a single"

        echo "        set of isos, or an exploded tree like an ftp site."

        exit 1

fi


DVD_DIR=`dirname $2`

DVD_FILE=`basename $2`


echo "DVD directory is $DVD_DIR"

echo "ISO file is $DVD_FILE"


if [ "$DVD_DIR" = "." ]; then

    echo "Destinaton Directory $DVD_DIR does not exist"

    exit 1

else

    if [ ! -d "/$DVD_DIR" ]; then

        echo "Destinaton Directory $DVD_DIR must be an absolute path"

        exit 1

    else

        if [ "$DVD_FILE" = "" ] || [ -d "$DVD_DIR/$DVD_FILE" ]; then

            echo "Null ISO file name."

            exit 1

        fi

    fi

fi


which mkisofs >&/dev/null

if [ "$?" != 0 ]; then

    echo "mkisofs Not Found"

    echo "yum install mkisofs"

fi


which createrepo >&/dev/null

if [ "$?" != 0 ]; then

    echo "createrepo Not Found"

    echo "yum install createrepo"

fi


if [ -f $2 ]; then

    echo "DVD ISO destination $2 already exists. Remove first to recreate."

    exit 1

fi


# Make sure there is enough free space to hold the DVD image on the filesystem

# where the home directory resides, otherwise change ~/mkrhdvd to point to

# a filesystem with sufficient free space.


cleanup() {

    [ ${LOOP:=/tmp/loop} = "/" ] && echo "LOOP mount point = \/, dying!" && exit

    [ -d $LOOP ] && rm -rf $LOOP 

    [ ${DVD:=~/mkrhdvd} = "/" ] && echo "DVD data location is \/, dying!" && exit

    [ -d $DVD ] && rm -rf $DVD 

}


cleanup

mkdir -p $LOOP

mkdir -p $DVD


ls $1/*.iso &>/dev/null

if [ "$?" = 0 ]; then


    echo "Found ISO CD images..."


    CDS=`expr 0`

    DISKS="1"


    [ -w / ] || {   # Very portable, but perhaps not perfect, test for superuser.

        echo "Only 'root' may use this script for loopback mounts" 1>&2

        exit 1

    }


    for f in `ls $1/*.iso`; do

        mount -o loop $f $LOOP

        cp -av $LOOP/* $DVD

        if [ -f $LOOP/.discinfo ]; then

            cp -av $LOOP/.discinfo $DVD

            CDS=`expr $CDS + 1`

            if [ $CDS != 1 ] ; then

                DISKS=`echo ${DISKS},${CDS}`

            fi

        fi

        umount $LOOP

    done

else

    if [ -f $1/isolinux/isolinux.bin ]; then


        echo "Found FTP-like tree..."


        if [ -e $1/.discinfo ]; then

            cp -av $1/.discinfo $DVD

        else

# How does one construct a legal .discinfo file if none is found?

            echo "Error: No .discinfo file found in $1"

            cleanup

            exit 1

        fi

        cp -av $1/* $DVD

    else

        echo "Error: No CD images nor FTP-like tree found in $1"

        cleanup

        exit 1

    fi

fi


if [ -e $DVD/.discinfo ]; then

    awk '{ if ( NR == 4 ) { print disks } else { print ; } }' disks="ALL" $DVD/.discinfo > $DVD/.discinfo.new

    mv $DVD/.discinfo.new $DVD/.discinfo

else

    echo  "Error: No .discinfo file found in $DVD"

    cleanup

    exit 1

fi


rm -rf $DVD/isolinux/boot.cat

find $DVD -name TRANS.TBL | xargs rm -f


cd $DVD

createrepo -g repodata/comps.xml ./

mkisofs -J -R -v -T -o $2 -b isolinux/isolinux.bin -c isolinux/boot.cat -no-emul-boot -boot-load-size 8 -boot-info-table $DVD

if [ "$?" = 0 ]; then


    echo ""

    echo "Image complete, create md5sum..."


#  $IMPLANT --force $2

# Don't like forced mediacheck? Try this instead.

    $IMPLANT --supported-iso --force $2


    echo "Start cleanup..."


    cleanup


    echo ""

    echo "Process Complete!"

    echo "Wrote DVD ISO image to $DVD_DIR/$DVD_FILE"

    echo ""

else

    echo "ERROR: Image creation failed, start cleanup..."


    cleanup


    echo ""

    echo "Failed to create ISO image $DVD_DIR/$DVD_FILE"

    echo ""

fi


使用方法: # mkdvdiso.sh source /destination/DVD.iso


顺便想起来点东西:在linux系统中拷贝文件至USB设备中时，在cp命令执行完成以后记住要执行几次sync命令。

因为拷贝的过程分程是: 磁盘 --> 内存的cache区域 --> 内存的buffer区域 --> 系统会找个合适的时机将内容再拷贝至USB,所以可以执行几次sync 来将buffer中的数据写入USB

其实在/etc/fstab配置文件中,系统为了提高效率，默认的defaults中的选项不就是async的吗(man 5 fstab 配置文件帮助！你值得拥有)