Bug 21059 – install.sh: posix_terminal returns false on Linux Mint 20

As originally discussed at https://forum.dlang.org/post/[email protected] I just upgraded a machine to Linux Mint 20 on a fresh install and tried to run the install script. It fails with main: line 178: USERPROFILE: unbound variable This line should only be called on Windows, which I found strange. It turns out that this is driven by ``` posix_terminal() { # If this script is run on Windows cmd by passing it as argument to bash.exe, # the shell level will be 1. If it is run from a POSIX terminal, it will be > 1. if [ "$SHLVL" = 1 ]; then false else true fi } ``` Running `echo $SHLVL` prints `1` Running ``` bash echo $SHLVL ``` prints `2` Running `echo $SHELL` prints `/bin/bash` The issue seems to be related to an update to Ubuntu 16: https://askubuntu.com/questions/856532/why-is-shlvl-initially-2-in-ubuntu-16-10-but-not-earlier-versions

Comments on the forum from Bastiaan Veelo suggested that the issue is not related to a specific version of Ubuntu, but may be due to how bash is (or is not) called. This also is an issue for using docker. https://github.com/dlang/installer/commit/e084815001390538bbd6fe5be7c2d4d81ee681b7#commitcomment-40487617

Confirmed: $ curl -fsS https://dlang.org/install.sh | bash -s dmd main: line 178: USERPROFILE: unbound variable Workaround: $ wget https://dlang.org/install.sh $ chmod +x install.sh $ ./install.sh $ source ~/dlang/dmd-2.093.0/activate $ dmd --version DMD64 D Compiler v2.093.0 Copyright (C) 1999-2020 by The D Language Foundation, All Rights Reserved written by Walter Bright So the pipe into bash does not seem to increment $SHLVL.

@veelo created dlang/installer pull request #463 "Fixes issue 21059: installer fails when piped on Posix." fixing this issue: - Fixes issue 21059. The assumption that $SHLVL increases when the script is run does not always hold. $SHLVL does not increase if the script is piped into bash, thereby failing to detect Posix. If the default terminal shell is not bash, $SHLVL might also be 1 on Posix. https://github.com/dlang/installer/pull/463

dlang/installer pull request #463 "Fixes issue 21059: installer fails when piped on Posix." was merged into stable: - 719ebf6f472b2b2d58b56fef2aebbf530cc5bcf3 by Bastiaan Veelo: Fixes issue 21059. The assumption that $SHLVL increases when the script is run does not always hold. $SHLVL does not increase if the script is piped into bash, thereby failing to detect Posix. If the default terminal shell is not bash, $SHLVL might also be 1 on Posix. https://github.com/dlang/installer/pull/463