5mo ago

correct way to `echo | sudo tee`

Can someone explain why this would make the command wait forever? What is tee waiting for?

 bash

    
echo "test" | sudo tee newfile

What would be a scriptable workaround for such cases?

Edit: this command would not terminate in zsh. This works fine in bash tho.

17 comments

Can’t reproduce.

16:22:48:~/tmp$ echo foo | sudo tee newfile [sudo] Passwort für bleistift2: foo 16:23:02:~/tmp$ ls -l newfile -rw-r--r-- 1 root root 4 Feb 23 16:22 newfile
- I just switched over to bash and it worked lol. It just didn't return for me in zsh...
  
  I use zsh and it works fine for me fwiw. Same with zsh --no-rcs (which doesn't load zshrc). Maybe you have some weird setting enabled?
  
  My initial guess was that sudo would eat up the echo’d foo as the password. Maybe sudo works differently when invoked via zsh?
  
  It works here in zsh, did you mistype the closing quote? Although that alters my prompt.
Maybe it's silently prompting you for your password?
I'm gonna take a couple of stabs in the dark.
According to this Stack Overflow answer using tee can prevent the prompt from drawing which makes it appear that a script has not terminated. The answerer's workaround is to put a very short sleep command after the tee command.
If this is what happened to you maybe the reason the script works in bash but not in zsh is because you have different prompts configured in those two shells.
Another idea is to replace tee with sponge from moreutils. The difference is that sponge waits for the end of stdin before it starts writing which can avoid problems in some situations.
- Nice one, didn't know about moreutils. I indeed used p10k on top of zsh. New zsh instance without sourcing anything zsh --no-rcs managed to write to file without issues. Thanks
Why does newfile need sudo to be created?
You need it to be owned by root?
- yeah indeed. I'm setting up a container with these instructions for ROS2. There you'll have to add a repository to the apt sources list.
  
  ROS
  Fly you fools!
Are you saying it waits forever, or you read somewhere it will wait forever and you want clarification?
Guessing that file doesn't exist already is the problem, and you don't even need to use tee in this example.
- what I was saying was that echo "text" | sudo tee newfile would hang and never return and needs to be interrupted. I just noticed this does not happen in bash but I was testing in zsh.
  Guessing that file doesn't exist already is the problem, and you don't even need to use tee in this example.
  you've missed the point here I'm afraid. But I'll blame it on my for not explaining properly what I was intending to do.
  
  ZSH is bash-compliant, but will not always behave like bash in all situations.
  Add sh -c before echo and see if that works

17 comments