Ensure that /bin/sh is indeed bash, or change the /bin/sh scripts to live without bashisms about nix-installer

[Hoverbear]

Thanks for raising this! The next version of the installer lowers this from an error to a warning so the situation will be a bit better! Still, labelling this as a bug.

[dnkmmr69420]

also use #!/usr/bin/env bash not #!/bin/bash

[Hoverbear]

The installer does not use #!/bin/bash anywhere, and the relevant scripts also don't use a hashbang, please open a new issue if you have something unrelated, thanks!

[Hoverbear]

I was thinking about this issue more and I think that skipping the self-test is not what we want, for shells that are links to other shells, we may want to avoid editing the shell profile all together.

I'd not want to place a user in a situation where we leave them with a broken sh and simply skip the self-test on sh.

That being said, the culprit of this issue is like stemming from /etc/profile.d/logic.sh as stated in the error message. The nix-installer does not edit that file, so unless the error message is reporting the wrong error, I do not think this issue is caused by the installer, but by an already broken sh config?

[metaminimalist]

Greetings from the same debian 11 machine which raised the error :)

/etc/profile.d/logic.sh is a bash script:

#!/bin/bash

function extend_path_for_swipl {
   local SWIPL="/usr/local/logic/swipl"
   local BIN="${SWIPL}/bin"
   if [[ -d "${BIN}" ]]; then
      export PATH="${BIN}:${PATH}"
      export SWIPL_HOME="$SWIPL"
   fi
}

extend_path_for_swipl
unset extend_path_for_swipl

so I guess defining a "function" in it is legal.
It is not a debian thing, but stems from an installation of SWI prolog, it can be found here: https://www.swi-prolog.org/Download.html

No error would have occurred if not something had started /bin/sh -> /bin/dash.

This machine is like all my boxes somewhat modified to run /bin/zsh as the login shell for all accounts but root and postgres which run /bin/zsh-static. Most of the /bin/zsh accounts have a local zsh profile with command line completion for the task of the account.

So I can be pretty sure that I/my accounts/my machine did not start /bin/sh (which at the time pointed to /bin/dash).

The start of /bin/sh (which pointed to /bin/dash) may have happened from here

nix-installer/nix-installer.sh

Line 1 in 34d0b7e

#!/bin/sh

or maybe by the elevation to root `nix-installer` needs to run as `root`, attempting to escalate now via `sudo`...
Other candidates would be running things with sudo like curl $URL | sudo sh, by cron - IIRC all these stubbornly use /bin/sh regardless of the users login shell set in /etc/passwd.

I did not find any such things in the code, but then I am not firm enough in rust to guess what is in the sudo cstring.

[Hoverbear]

It's my assumption that /etc/profile.d/logic.sh existed (and thus sh was broken) before the nix install ever occured, so it being broken during self test makes sense since it was already broken.

Is this correct?

[metaminimalist]

This ist definitely correct, I installed SWI Prolog in last winter after xmas, and nix in July.

[metaminimalist]

So I spent a little bit of my sunday on that debian11 machine which triggered this issue:

• uninstalled nix
• uninstalled SWI Prolog
• made sure that there are no remnants in /etc and user profiles
• reverted to dash as /bin/sh
• kept /bin/zsh and /bin/zsh-static as login shells
• did a system upgrade to the latest packages for debian 11
• rebooted

After that the installer worked as intended :)

Conclusion:

• it works with /bin/sh -> dash on unmodified systems
• it works with /bin/sh -> bash even on modified systems
• it does not work with /bin/sh -> dash on modified systems and leaves a non-functioning nix install

("modified" means that this machine has eight foreign repositories configured, and heavily personalized shell profiles. The SWI prolog installation was only a software package, and any of the installation could have written to /etc/profile.d/)

Maybe you should threat this like the test for Apple's ksh93 which I found in the installer.

I consider this thing "worksforme" now, but the mileage or stamina of others will vary.

[Hoverbear]

If the user has a broken sh before the install, it seems like the self test reporting that sh is broken is expected, so I am not sure this is a bug or is in need of fixing. SWI prolog shipping a broken profile.d for dash is neither the installers problem nor responsibility.

I really appreciate your report and help debugging the issue! It's good Nix is working for you now.