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|
# dd(1)
Copy data `block-wise`.
```
dd [opts]
if=<path> input file to read (stdin in case not specified)
of=<path> oputput file to write
status=progress show progress while copying
bs=<bytes> block size
count=<n> copy only <n> blocks
skip=<n> skip <n> blocks in input (seek input)
seek=<n> skip <n> blocks in oputput (seek output)
conv=<conv>
notrunc dont truncate output file
excl fail if output already exists
nocreat fail if output does not exists
```
## Example: bootstick
```bash
dd bs=4M if=<iso> of=<blkdev> oflag=sync status=progress
```
## Example: patch file in place
```bash
# Create a 1024 bytes file filled with zeros.
dd if=/dev/zero of=disk bs=512 count=2
# Overwrite 4 bytes starting at byte 0.
printf "aaaa" | dd of=disk bs=1 seek=0 conv=notrunc
# Overwrite 4 bytes starting at byte 512.
printf "bbbb" | dd of=disk bs=1 seek=512 conv=notrunc
hexdump disk
# 0000000 6161 6161 0000 0000 0000 0000 0000 0000
# 0000010 0000 0000 0000 0000 0000 0000 0000 0000
# *
# 0000200 6262 6262 0000 0000 0000 0000 0000 0000
# 0000210 0000 0000 0000 0000 0000 0000 0000 0000
# *
# 0000400
```
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