The Linux Newbie Guide

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The dd command is a compact yet powerful conversion tool commonly used for both text and storage device transformations

Common parameters for text conversion include:

"if" (input file): Read from the specified input file.
"0f" (output file): Write to the specified output file.
"conv=lcase": Convert uppercase to lowercase.
"conv=ucase": Convert lowercase to uppercase.

Examples:

$ dd if=file of=file_up conv=ucase ←Converts content from file "file" to uppercase and stores it in file "file_up"

Another important feature of dd is converting block devices and files. This operation typically requires superuser privileges and poses risks. If not used carefully, it can result in data loss on the hard disk. For this reason, dd is sometimes referred to as a "data destroyer." However, dangerous tools often have dual purposes; dd is also commonly used for disaster recovery. For converting block devices, common parameters include:

"ibs" :Read block size (default is 512 bytes).
"obs" :Write block size (default is 512 bytes).
"bs" :Read and write block size (overrides "ibs" and "obs" if specified).
"count" :Process N blocks of "ibs".
"skip" :Skip input before processing.
"seek" : Skip output before processing.

Examples:

# dd if=CentOS-6.5-x86_64-bin-DVD1.iso of=/dev/sdc ←Create a bootable disk from an ISO file.
# dd if=/dev/sda of=/dev/sdb ←Copy hard drive (/dev/sda --> /dev/sdb)
# dd if=/dev/zero of=512M-image bs=512M count=1 ←Generate a 512M-sized file

For more information on dd operations and examples, please refer to the provided link.