创建一个交换文件

时间：2006-11-05 来源：0217

#!/bin/bash

# 创建一个交换文件.

ROOT_UID=0         # Root 用户的 $UID 是 0.

E_WRONG_USER=65    # 不是 root?

FILE=/swap

BLOCKSIZE=1024

MINBLOCKS=40

SUCCESS=0

# 这个脚本必须用root来运行.

if [ "$UID" -ne "$ROOT_UID" ]

then

echo; echo "You must be root to run this script."; echo

exit $E_WRONG_USER

fi

blocks=${1:-$MINBLOCKS}          # 如果命令行没有指定,

                                 #+ 则设置为默认的40块.

# 上面这句等同如：

# --------------------------------------------------

# if [ -n "$1" ]

# then

#   blocks=$1

# else

#   blocks=$MINBLOCKS

# fi

# --------------------------------------------------

if [ "$blocks" -lt $MINBLOCKS ]

then

blocks=$MINBLOCKS              # 最少要有 40 个块长.

fi

echo "Creating swap file of size $blocks blocks (KB)."

dd if=/dev/zero of=$FILE bs=$BLOCKSIZE count=$blocks # 把零写入文件.

mkswap $FILE $blocks             # 将此文件建为交换文件(或称交换分区).

swapon $FILE                     # 激活交换文件.

echo "Swap file created and activated."

exit $SUCCESS

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