How can I split a set of bytes into separate parts

ramonun · 04-30-2023, 07:03 AM

Code:

$ du -b 1GB.bin
1048576000      1GB.bin

$ split --verbose -b 120M 1GB.bin && du -b *xa*
125829120       xaa
125829120       xab
125829120       xac
125829120       xad
125829120       xae
125829120       xaf
125829120       xag
125829120       xah
41943040        xai

How can I split or divide the 1048576000 bytes above, or even bigger: 2GiB = 2147483648 bytes or 3GiB = 3221225472 bytes and so on, but without having to use the split utility, so that the result is exactly as above (per part is 120 MiB = 125829120 bytes, except for the last part, 40 MiB = 41943040 bytes) ?.

MadeInGermany · 04-30-2023, 08:09 AM

split without split?
You can use dd and a lot of shell code, but why?

ramonun · 04-30-2023, 08:15 AM

Quote:

Originally Posted by MadeInGermany

split without split?. You can use dd and a lot of shell code, but why?

The file hosting where I put the files allows for multipart uploads without having to split files. And would you like to give me an example of using dd based on my post above? Thank You.

rtmistler · 04-30-2023, 09:34 AM

Quote:

Originally Posted by ramonun

The file hosting where I put the files allows for multipart uploads without having to split files. And would you like to give me an example of using dd based on my post above? Thank You.

It's all in the dd manual page.
count, skip, and bs arguments.

pan64 · 04-30-2023, 10:34 AM

you can use a lot of tools like perl, python, dd, whatever, to count/copy XX bytes. But why do you want to reinvent split?

teckk · 04-30-2023, 10:53 AM

Simple Example:

Code:

touch myfile

for i in {1..100000}; do
    echo "$i" >> myfile
done

ls -l myfile
-rw-r--r-- 1 me me 588895 Apr 30 10:41 myfile

dd if=myfile of=myfile2 bs=10k count=1
dd if=myfile of=myfile3 bs=10k skip=1 count=1
dd if=myfile of=myfile4 bs=10k skip=2 count=1

Look at myfile2 3 and 4

ramonun · 04-30-2023, 10:54 AM

Quote:

Originally Posted by pan64

you can use a lot of tools like perl, python, dd, whatever, to count/copy XX bytes. But why do you want to reinvent split?

Read my reply here please.

pan64 · 04-30-2023, 11:39 AM

Quote:

Originally Posted by ramonun

Read my reply here please.

that is not an answer. At least I don't understand. However, you can still use a lot of different tools instead of split.
https://stackoverflow.com/questions/...file-in-python

rtmistler · 04-30-2023, 01:40 PM

Quote:

Originally Posted by ramonun

Read my reply here please.

Read my reply here please.

You asked about dd, I've cited the argument options you can use.

Given the demonstrable, and good split command you've shown, this should not be too difficult.

Further, one can use a very small, text file and experiment to ensure they know how to use the command arguments to attain their desired result.

Edit: also look at what user teckk posted, a dd example