FAQ: update "sh: can't access tty; job control turned off" section

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 15 insertions, 2 deletions

diff --git a/FAQ.html b/FAQ.html
index 7c5f2c2..1d995c1 100644
--- a/FAQ.html
+++ b/FAQ.html
@@ -617,13 +617,26 @@ int main(int argc, char *argv)
     # in the correct order:
     # 1. make ourself session leader,
     # 2. open /dev/tty1 and thus acquire a ctty,
-    # 3. re-execute the shell, allowing it to notice that it has ctty:
+    # 3. re-execute the shell, allowing it to notice that it has a ctty:
     exec setsid sh -c 'exec sh </dev/tty1 >/dev/tty1 2>&1'
 </pre>
 <p>
+    Note that above example talks about <em>interactive shell with PID 1</em>.
+    Thus, it painstakingly uses "exec ..." to keep you in PID 1.
+    If you have "sh: can't access tty" problem when you run interactive shell
+    from, say, an init shell script (IOW: you boot with init=/some/shell/script.sh,
+    and script.sh runs "sh" at some point in order to allow user to type
+    in commands), then execing will be a wrong thing to do. You will need to drop it:
+<pre>
+    setsid sh -c 'exec sh &lt;/dev/tty1 &gt;/dev/tty1 2&gt;&amp;1'
+    # or using a hack tool:
+    setsid cttyhack sh
+</pre>
+
+<p>
     If you <em>REALLY</em> want your shell
     to run on /dev/console, then you can hack your kernel (if you are into that
-    sortof thing) by changing drivers/char/tty_io.c to change the lines where
+    sort of thing) by changing drivers/char/tty_io.c to change the lines where
     it sets "noctty = 1;" to instead set it to "0".  I recommend you instead
     run your shell on a real console.
 </p>