My tentative patch:

--- a/platform/android/luajit-launcher/assets/android.lua
+++ w/platform/android/luajit-launcher/assets/android.lua
@@ -2642,13 +2642,7 @@ local function run(android_app_state)
 
     os.execute = function(command) -- luacheck: ignore 122
         if command == nil then return -1 end
-        local argv = {}
-        command:gsub("([^ ]+)", function(arg)
-            -- strip quotes around argument, since they are not necessary here
-            arg = arg:gsub('"(.*)"', "%1") -- strip double quotes
-            arg = arg:gsub("'(.*)'", "%1") -- strip single quotes
-            table.insert(argv, arg)
-        end)
+        local argv = {'sh', '-c', command}
         return android.execute(unpack(argv))
     end

--- a/plugins/terminal.koplugin/main.lua
+++ b/plugins/terminal.koplugin/main.lua
@@ -93,29 +93,35 @@ local Terminal = WidgetContainer:extend{
 }
 
 function Terminal:isExecutable(file)
-    if os.execute(string.format("test -x %s", file)) == 0 then -- full path
-        return true
-    elseif os.execute(string.format("which %s 2>/dev/null 1>/dev/null", file)) == 0 then
-        return true
-    end
+    -- check if file is an executable or a command in PATH
+    return os.execute(string.format("test -x %s || command -v %s", file, file)) == 0
 end
 
 -- Try SHELL environment variable and some standard shells
 function Terminal:getDefaultShellExecutable()
     if self.default_shell_executable then return self.default_shell_executable end
 
-    local shell = {"mksh", "ksh", "zsh", "ash", "dash", "sh", "bash"}
-    table.insert(shell, os.getenv("SHELL"))
+    local shell = {
+        -- os.getenv("SHELL"),
+        "pouet",
+        "bash",
+        "sh",
+        "dash",
+        "ash",
+        "zsh",
+        "ksh",
+        "mksh",
+    }
 
-    while #shell >= 1  do
-        if self:isExecutable(shell[#shell]) then
-            self.default_shell_executable = shell[#shell]
+    for i, file in ipairs(shell) do
+        if self:isExecutable(file) then
+            self.default_shell_executable = file
             break
-        else
-            shell[#shell] = nil
         end
     end
 
+    logger.info('Terminal:default shell', self.default_shell_executable)
+
     return self.default_shell_executable
 end
 

I am not quite fond with your patch

1. it calls the 'test -x' command with `sh -c`. (This could be done easier)

If our os.execute implementation for android is to be compatible with all current use cases, that's the only way (e.g. when using cmd … >redirection).

2. it depends on the shell built in `command`.

It's a POSIX shell builtin, so any compatible shell must support it.

The getDefaultShellExecutable method looks good.

Another thing that does not really make sense to me: sh in the middle of the list, which platform is going to have dash, or zsh, but not sh?

Also, I forgot to uncomment the os.getenv("SHELL") option, and to remove my pouet test. :P

ipairs will stop at the first entry if $SHELL is undefined (nil). Though it occurs to me the current code may have a similar issue since string.format will balk on nil.The current code doesn't have such an issue because table.insert(t, nil) at the end does nothing.

The most straightforward solution is probably

    local shell = {
        os.getenv("SHELL") or "",


if file ~= "" and self:isExecutable(file) then

but there might be a more elegant solution.

Edit: the current code is the more elegant solution.

So this works on the emulator, a Kobo Sage and a Android Pixel (Android S).

ping @benoit-pierre Does this PR fix your issue on Marshmallow?

No, still the same issue:

19:27:32.229  2785:2799       ProcessManager  W  waitpid on failed exec failed: No child processes
19:27:32.231  2785:2799                  art  F  art/runtime/java_vm_ext.cc:410] JNI DETECTED ERROR IN APPLICATION: JNI GetObjectClass called with pending exception java.io.IOException: Error running exec(). Command: [test, -x, bash] Working Directory: null Environment: null

Thanks, I will look into that tomorrow.
I feel (but have not found any docu on that), that bionic fork does something with the environment of the forked process.

No, still the same issue:

19:27:32.229  2785:2799       ProcessManager  W  waitpid on failed exec failed: No child processes
19:27:32.231  2785:2799                  art  F  art/runtime/java_vm_ext.cc:410] JNI DETECTED ERROR IN APPLICATION: JNI GetObjectClass called with pending exception java.io.IOException: Error running exec(). Command: [test, -x, bash] Working Directory: null Environment: null

Btw could you Post a langer Part of the crash.log, pleas?

Here's the full log.

Thanks @benoit-pierre ;
You were almost right with your changed os.execute (mind the additional exit $?, to get the exit value of the command and not of the shell there).

It might be the main cause, that android does not have a system shell running -> os.execute() returns nil.

Before changing luajit-launcher, could you please test, if it works on Marshmallow now?

@benoit-pierre So much questions! I Just politely asked If this Works ... I expected an answer