Debian post install script issues

[Jmennius]

• Electron-Builder Version: 26.0.0-alpha.7

• Node Version: 22.11.0

• Electron Version: ^33.2.0
• Electron Type (current, beta, nightly): current

• Target: x86_64, Debian package

When installing a package I see the following: /var/lib/dpkg/info/<package-name>.postinst: 30: [[: not found.
Essentially, the postisnt from fpm uses /bin/sh shebang, which is not bash by default on most Debian systems (Ubuntu as well).
So the script is running in the POSIX shell (or in compat mode at the very least), so some things do not work as expected.

At least for Debian packages:

1. the shebang does not have any effect, it's just a comment, fpm will put the code from after-install.tpl inside a function.
2. bash test builtin does not work because the shell is not bash.
3. another bashism is type which is apparently and optional part of POSIX (or rather an extension)

[mmaietta]

Fantastic callout/discovery and details. Would you be willing to open a PR with the /bin/sh-supported command?

[Jmennius]

Fantastic callout/discovery and details. Would you be willing to open a PR with the /bin/sh-supported command?

In general, yes, but I'm kind of not sure when I would be able to :)