[dannyshafer]

The bash/zsh preamble re-execs any interactive shell attached to a terminal as atuin pty-proxy, which drops the command passed to bash -ic or zsh -ic and leaves the user at a prompt. Skip the re-exec when BASH_EXECUTION_STRING or ZSH_EXECUTION_STRING is set.

Fixes #4412

Edit by @taylordotfish: I added support for detecting bash -i <file> and zsh -i <file> too. There are some caveats as it isn't possible to check for this with 100% accuracy. In particular, these cases will continue to have incorrect behavior:

• Zsh:

  • If the basename of <file> is zsh or -zsh, we will incorrectly spawn a proxy (though this can depend on whether the shell is a login shell).
  • If Zsh is spawned with a custom argv[0], we will, in general, not spawn a proxy even though we should. However, before this PR, we would actually try to execute argv[0] which would simply kill the shell, so this is an improvement. (Note that if argv[0] happens to be a valid executable, we will still incorrectly execute it as before.)
  • If Zsh is an older version that doesn't set ZSH_ARGZERO, we can't detect when we're reading from a file and will always spawn a proxy.

• Bash:

  • If <file> is bash or -bash, we will incorrectly spawn a proxy (though can depend on whether the shell is a login shell).
  • If Bash is invoked via a relative path (./bin/bash) and the shell has changed CWD before the proxy check is run, we will not spawn a proxy even though we should.
  • If Bash is spawned with a custom argv[0], we will, in general, not spawn a proxy even though we should.
  • If Bash is started as a login shell but the user's shell in /etc/passwd isn't Bash, we will not spawn a proxy even though we should. However, before this PR, we would incorrectly execute that non-Bash program, so this is an improvement. However, if the /etc/passwd shell is a different installation of Bash, we will still incorrectly spawn that other Bash as before.
  • If Bash is older than version 5.2, we can't detect when we're reading from a file and will always spawn a proxy.

Checks

• I am happy for maintainers to push small adjustments to this PR, to speed up the review cycle
• I have checked that there are no existing pull requests for the same thing

[greptile-apps]

Confidence Score: 5/5

[Medium impact] The PR appears safe to merge; no actionable new issues were found.

Summary

Prevents Bash and Zsh from replacing command or file invocations with a PTY proxy.

• Bash and Zsh run supplied commands and files before the proxy takes over.

_{Reviews (3) · Last reviewed commit: "Fix tests on older Bash" · Reviewed by Greptile}

[taylordotfish]

Thanks for the PR! I'm trying to see if we can also detect bash -i <file> too, since that has the same problem. Unfortunately, it doesn't appear to be as easy to detect whether a file was passed.

[taylordotfish]

/merge

[atuin-bot]

Landed as 658b539. GitHub shows this merged once it reaches main.