cttyhack: document the need to setsid

function                                             old     new   delta
packed_usage                                       26988   27057     +69

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

1 files changed, 13 insertions, 2 deletions

diff --git a/shell/Config.in b/shell/Config.in
index 3b1650615..36a931715 100644
--- a/shell/Config.in
+++ b/shell/Config.in
@@ -354,9 +354,20 @@ config CTTYHACK
           It analyzes stdin with various ioctls, trying to determine whether
           it is a /dev/ttyN or /dev/ttySN (virtual terminal or serial line).
           If it detects one, it closes stdin/out/err and reopens that device.
-          Then it executes given program. Usage example for /etc/inittab
-          (for busybox init):
+          Then it executes given program. Opening the device will make
+          that device a controlling tty. This may require cttyhack
+          to be a session leader.
+
+          Example for /etc/inittab (for busybox init):
 
           ::respawn:/bin/cttyhack /bin/sh
 
+          Giving controlling tty to shell running with PID 1:
+
+          $ exec cttyhack sh
+
+          Starting an interative shell from boot shell script:
+
+          setsid cttyhack sh
+
 endmenu