hush: explain why "pipe; exit $?" doesn't show correct exitcode

git-svn-id: svn://busybox.net/trunk/busybox@18507 69ca8d6d-28ef-0310-b511-8ec308f3f277

1 files changed, 5 insertions, 0 deletions

diff --git a/shell/README b/shell/README
index 32ad67380..bcd84dcad 100644
--- a/shell/README
+++ b/shell/README
@@ -1,5 +1,10 @@
 Various bits of what is known about busybox shells, in no particular order.
 
+2007-04-22
+hush: "sleep 1 | exit 3; echo $?" prints 0 because $? is substituted
+_before_ pipe gets executed!! run_list_real() already has "pipe;echo"
+parsed and handed to it for execution, so it sees "pipe"; "echo 0".
+
 2007-04-21
 hush: removed setsid() and made job control sort-of-sometimes-work.
 Ctrl-C in "rm -i" works now except for SH_STANDALONE case.