[PATCH] Terminate zgrep gracefully when a pipeline is interrupted by a signal

[Dmitry V. Levin]

zgrep is not terminated gracefully when its grep/sed pipeline is
terminated by a signal.  For example, a command like
zgrep -F .TH /usr/share/man/man1/*.gz |head
works long time after the "head" completion.
Another example, a command like
zgrep unmatched-pattern /usr/share/man/man1/*.gz
cannot be interrupted by sending a SIGQUIT with Ctrl-\ key, it outputs
zgrep: line 221: test: : integer expression expected
and goes on.
* zgrep.in: Terminate gracefully when the grep/sed pipeline is
terminated by a signal.

---
 zgrep.in |    9 +++++++--
 1 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/zgrep.in b/zgrep.in
index a828bbc..e80dae0 100644
--- a/zgrep.in
+++ b/zgrep.in
@@ -213,11 +213,16 @@ do
       r=$(
        exec 4>&1
        (eval "$grep" 4>&-; echo $? >&4) 3>&- | sed "$sed_script" >&3 4>&-
-      ) || r=2
-      exit $r
+      ) && exit $r
+      r=$?
+      test $r -gt 128 -a $r -le 143 && exit $r || exit 2
     fi >&3 5>&-
   )
   r=$?
+  if test $r -gt 128 -a $r -le 143; then
+    kill -$(($r-128)) $$
+    exit $r
+  fi
   test "$gzip_status" -eq 0 || test "$gzip_status" -eq 2 || r=2
   test $res -lt $r && res=$r
 done
-- 
ldv