如何创建交换文件?

如何创建交换文件?

我有 500Gib 硬盘和 2Gib RAM。我有 ubuntu 12.04

当我最初分配磁盘时,我有未分配的空间,因为我有另一个装有 Windows 的磁盘。这个磁盘坏了,所以我必须在这个磁盘上安装 Windows,并且必须擦除交换分区。

现在,由于我处理大量图片、视频等,计算机运行缓慢,我想这是因为我没有交换文件。

我的一个朋友给了我下面的命令,但是计数数字给了我 2Gib 的交换文件,而我想要 4 Gib 的交换文件。

请问您能告诉我要输入哪个数字吗?

sudo dd if=/dev/zero of=/swapfile.swap bs=4096 count=1048576

答案1

要创建 4GB 的交换文件,您可以运行:

sudo dd if=/dev/zero of=swapfile bs=1K count=4M

因此通过使用乘法后缀可以更容易地计算(1K * 4M = 4 GiB)。

然后您需要将该文件转换为交换空间,并启用它,因此:

sudo mkswap swapfile
sudo swapon swapfile

欲了解更多详情,请查看:我如何添加交换?

答案2

创建交换文件的基本步骤如下:建筑维基关于 swap 的文章。我擅自将所有这些步骤浓缩成一个脚本。基本用法:

使用方法非常简单:

sudo ./addswap.sh INTEGER LETTER

要添加 1 GB,您需要执行sudo ./addswap.sh 1 G。要添加 1 MB,您需要执行sudo ./addswap.sh 1 M

脚本

此脚本也可在我的个人 GitHub 仓库

#!/bin/bash
set -e  # bail if anything goes wrong

is_root(){
   if [ "$( id -u )" -ne 0  ] ; then
      return 1
   fi
   return 0
}

get_swap_amount(){
    # Obtain amount of swap in Gigabytes
    awk '/SwapTotal/{printf "%.2f",($2/1048576)}' /proc/meminfo
}

make_swap_file(){ 
   # This is the function that does the job of creatig swap file
   # and enabling it.  All files are timestamped
   printf "Current swap ammount: %f\n" "$(get_swap_amount)"
   printf "Working on creating swap file\n"
   DATE=$(date +%s) # append date of creation to filename
   filename="/swapfile.""$DATE" # File will be /swapfile.$DATE
   dd if=/dev/zero  of="$filename" bs=1"$2" count="$1"
   chmod 600 "$filename"
   mkswap "$filename" && 
   swapon "$filename" && 
   printf "\nCreated and turned on %s\n"  "$filename"
   printf "Current swap ammount: %f" "$(get_swap_amount)"
}


ask_to_enable_on_boot(){
   # Prompt user to enable this new swap file on boot. If user
   # enters y, the swap file will be added to /etc/fstab
   printf "Do you want to turn on this file at boot?[y/n]\n"
   read ANSWER
   case "$ANSWER" in
    [Yy]) printf "\n%s none swap defaults 0 0\n" "$filename"  >> /etc/fstab &&
       printf "\n %s added to /etc/fstab successfuly\n" "$filename"
       exit 0 ;;
    [Nn]) printf "Exiting\n" && exit 0 ;;
    *) printf "Wrong input: %s . Exiting. /etc/fstab not altered\n" "$ANSWER" && exit 1 ;;
   esac

}

bad_arguments(){
     # check if second argument is a character 
     case "$2" in 
         [A-Z]) return 1;;
         *) return 0;;
     esac

    # Check if first argument is a digit. 
    # https://stackoverflow.com/a/3951175/3701431
    case "$1" in
        ''|*[!0-9]*) return 0;;
        *) return 1 ;;
    esac 

}

main(){

    # Check if we're root and if args are OK. If everything is ok, do stuff

    if is_root 
    then
        if [ $# -ne 2   ] ||  bad_arguments "$@"
        then
            printf "%s\n" ">>> ERR: $0: bad or insufficient arguments" > /dev/stderr
            printf "%s\n" ">>> Usage: $0 INTEGER LETTER" > /dev/stderr
            exit 2
        fi
        make_swap_file "$@" && ask_to_enable_on_boot
    else
        printf ">>> ERR: $0 must run as root\n" > /dev/stderr
        exit 1
    fi
}

main "$@"

测试运行

$ sudo ./addswap.sh 1 G                                                                                                                                                                 
[sudo] password for xieerqi: 
Current swap ammount: 4.000000
Working on creating swap file
1+0 records in
1+0 records out
1073741824 bytes (1.1 GB, 1.0 GiB) copied, 6.83322 s, 157 MB/s
Setting up swapspace version 1, size = 1024 MiB (1073737728 bytes)
no label, UUID=8bf1d78d-0a8a-478b-a783-38c5935c362f

Created and turned on /swapfile.1498976162
Current swap ammount: 5.000000Do you want to turn on this file at boot?[y/n]
Y

 /swapfile.1498976162 added to /etc/fstab successfuly
 $ 

答案3

将您的计数乘以 2。

如果
  1048576 个块(每个大小为 4086 字节)= 2GB
,那么
  2097152 个块(每个大小为 4086 字节)= 4GB

对于其他读者来说,上述数值并不准确。它们基于 OP 给出的数值

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