Send output from `split` utility to stdout

Question

From this question, I found the split utilty, which takes a file and splits it into evenly sized chunks. By default, it outputs these chunks to new files, but I'd like to get it to output them to stdout, separated by a newline (or an arbitrary delimiter). Is this possible?

I tried cat testfile.txt | split -b 128 - /dev/stdout

which fails with the error split: /dev/stdoutaa: Permission denied.

Looking at the help text, it seems this tells split to use /dev/stdout as a prefix for the filename, not to write to /dev/stdout itself. It does not indicate any option to write directly to a single file with a delimiter. Is there a way I can trick split into doing this, or is there a different utility that accomplishes the behavior I want?

Answer 1

It's not clear exactly what you want to do, but perhaps the --filter option to split will help out:

   --filter=COMMAND
          write to shell COMMAND; file name is $FILE

Maybe you can use that directly. For example, this will read a file 10 bytes at a time, passing each chunk through the tr command:

split -b 10 --filter "tr [:lower:] [:upper:]" afile

If you really want to emit a stream on stdout that has separators between chunks, you could do something like:

split -b 10 --filter 'dd 2> /dev/null; echo ---sep---' afile

If afile is a file in my current directory that looks like:

the quick brown fox jumped over the lazy dog.

Then the above command will result in:

the quick ---sep---
brown fox ---sep---
jumped ove---sep---
r the lazy---sep---
 dog.
---sep---

Answer 2

From info page : `--filter=COMMAND' With this option, rather than simply writing to each output file, write through a pipe to the specified shell COMMAND for each output file. COMMAND should use the $FILE environment variable, which is set to a different output file name for each invocation of the command.

split -b 128 --filter='cat ; echo ' inputfile

Answer 3

Here is one way of doing it. You will get each 128 character into variable "var".

You may use your preferred delimiter to print or use it for further processing.

#!/bin/bash

cat yourTextFile | while read -r -n 128 var  ; do
    printf "\n$var"
done

You may use it as below at command line:

while read -r -n 128 var  ; do printf "\n$var" ; done < yourTextFile