Common operations of DD command under linux - the road to dream building

DD command introduction

ddcommand is LINUXa command-line tool for data transformation and processing. ddStands for " data copy ," which reads data from one device or file and writes it to another. ddCommands can be used for a variety of purposes, including the following:

• Disk backup and cloning

• Data Recovery

• blank file creation

• Password cracking

Features of the DD command

• Flexibility: Can be used for a variety of data processing and transformation operations, including backup and clone disks, data recovery, disk wiping, blank file creation, and more.

• Reliability: Using the underlying block device interface to read and write data, the data can be completely copied to ensure data consistency and integrity.

• Efficiency: Various caching mechanisms can be used to improve data transmission speed and make data replication more efficient.

• Sensitivity: Different block sizes and cache sizes can be used and adjusted as needed to accommodate different hardware and data transfer requirements.

• Versatility: It can run on different operating systems and hardware platforms, and has strong versatility.

DD Command Common Parameters

ddThe command can copy a file in blocks of a specified size, and perform specified transformations while copying.

parameter	note
if=文件名	Input file name, defaults to standard input. That is, specify the source file. <if=input file>
of=文件名	The output file name, the default is standard output. That is, specify the destination file. <of=output file>
ibs=bytes	Read bytes bytes at a time, that is, specify a block size of bytes bytes
obs=bytes	Output bytes bytes at a time, that is, specify a block size of bytes bytes
bs=bytes	Also set the block size of read/output to bytes bytes
cbs=bytes	Convert bytes bytes at a time, that is, specify the conversion buffer size
skip=blocks	Skip blocks blocks from the beginning of the input file before starting copying
seek=blocks	Skip blocks blocks from the beginning of the output file before starting copying
status=progress	Display progress information, such as the number of bytes copied per second and the progress percentage, etc.

Example of using the DD command

# 复制文件内容

dd if=input.txt of=output.txt bs=1024

将input.txt文件复制到output.txt文件中，块大小为1024字节

# 将一个磁盘的内容复制到另一个磁盘中

dd if=/dev/sda of=/dev/sdb bs=4096

将/dev/sda磁盘的内容复制到/dev/sdb磁盘中，块大小为4096字节

# 将一个磁盘的内容复制到一个文件中

dd if=/dev/sda of=image.img bs=4096 count=1000 status=progress

将/dev/sda磁盘的前1000个块复制到image.img文件中，块大小为4096字节，并显示进度信息

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# 创建空文件

dd if=/dev/zero of=newfile bs=1M count=10

创建一个名为newfile的文件，大小为10MB，其中每个块的大小为1MB

# 磁盘克隆

dd if=/dev/sda of=/dev/sdb bs=4096 conv=noerror,sync

将/dev/sda磁盘的内容复制到/dev/sdb磁盘中，块大小为4096字节。conv=noerror,sync表示在复制过程中忽略读取错误，并将输出同步到磁盘中

#  数据恢复

dd if=/dev/sda1 of=/mnt/usbdrive/recovered_data.img bs=4096 conv=noerror,sync

将/dev/sda1分区的内容复制到/mnt/usbdrive/recovered_data.img文件中，块大小为4096字节。conv=noerror,sync表示在复制过程中忽略读取错误，并将输出同步到磁盘中

#  密码破解

dd if=/dev/sda | john --stdin

将/dev/sda磁盘的内容传递给john密码破解工具，用于破解磁盘中的密码




ddrescue命令：用于数据恢复，可以在损坏的磁盘上执行数据恢复操作