Bash: warning: command substitution: ignored null byte in input

Questions : Bash: How to force not to ignore null bytes

2022-09-18T18:41:18+00:00 2022-09-18T18:41:18+00:00

746

I want to put exactly anycodings_null \xc0Ib\xff\xff\x7f\x00\x00\xd5N_\xff\xff\x7f\x00\x00 anycodings_null as a command parameter, but unfortunetly anycodings_null bash is ignoring null-bytes:

warning: command substitution: ignored null byte in input

How can I force bash not to ignore those anycodings_null null bytes?

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Total Answers 0

Jake

Guest

  • #1

Jake Asks: How do I ignore "command substitution: ignored null byte in input"?
I have this Linux shell command:

Code:

echo $(python3 -c 'print("Test"+"\0"+"M"*18)') | nc -u [IP] [PORT]

My intention is to pipe the output of the print statement to the netcat command. The netcat command creates a socket to some service that essentially returns an stdout of the string passed in.

The problem here is that when I try to run this command, I get this message: -bash: warning: command substitution: ignored null byte in input; and my null byte \0 gets ignored. But I don't want the null byte to be ignored.

How do I tell the system to NOT ignored my null byte and take in the input exactly as I've specified.

I have done some Google searches but honestly speaking they haven't helped much. Also, any link to some great article is much appreciated.


EDIT

Using printf worked.

Ordinarily passing python3 -c 'print("Test"+"\0"+"M"*18)' also worked. Valued @cas explanation. I guess I might be sticking to printf given it's faster (though speed isn't particularly a concern in my case).

Thanks to all those who contributed .

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Bash: warning: command substitution: ignored null byte in input

[![nextconfig.json

Bash: warning: command substitution: ignored null byte in input

Bash: warning: command substitution: ignored null byte in input

Bash: warning: command substitution: ignored null byte in input

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