Is dd able to overwrite parts of a file? I have a 1TB big file (disk-image from a damaged drive) and a 1.3MB small file (beginning of a disk-file). Using the contents of the small file, I want to overwrite portions of the big file. That is, I want to insert/overwrite the first 1.3MB of the 1TB-image using the small file. Using small temporary files for testing I was unable to overwrite parts of the files. Rather, dd overwrote the files completely. This is not what I want. Is dd able to do this?

If you use the `conv=notrunc` argument, you can replace just the first however many bytes.
e.g. `dd conv=notrunc if=small.img of=large.img`


root@debian:~/ddtest# dd if=/dev/zero of=file1.img bs=1M count=10
10+0 records in
10+0 records out
10485760 bytes (10 MB) copied, 1.14556 s, 9.2 MB/s
root@debian:~/ddtest# dd if=/dev/urandom of=file2.img bs=1M count=1
1+0 records in
1+0 records out
1048576 bytes (1.0 MB) copied, 0.207185 s, 5.1 MB/s
root@debian:~/ddtest# head file1.img

<< Blank space here as it's all Zeroes >>

root@debian:~/ddtest# dd conv=notrunc if=file2.img of=file1.img
2048+0 records in
2048+0 records out
1048576 bytes (1.0 MB) copied, 0.00468016 s, 224 MB/s
root@debian:~/ddtest# head file1.img
^vyے! E91 << SNIP Random garbage >>
root@debian:~/ddtest#