Configuration Information [Automatically generated, do not change]:
Machine: x86_64
OS: linux-gnu
Compiler: gcc
Compilation CFLAGS: -DPROGRAM='bash' -DCONF_HOSTTYPE='x86_64'
-DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='x86_64-redhat-linux-gnu'
-DCONF_VENDOR='redhat'
+-DLOCALEDIR='/usr/share/locale' -DPACKAGE='bash' -DSHELL
-DHAVE_CONFIG_H -I. -I. -I./include -I./lib -D_GNU_SOURCE
-DRECYCLES_PIDS -O2 -g -pipe -Wall
+-Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector
--param=ssp-buffer-size=4 -m64 -mtune=generic
uname output: Linux spoyarek.pnq.redhat.com
2.6.34-0.16.rc2.git0.fc14.x86_64 #1 SMP Tue Mar 23 02:02:52 UTC 2010
x86_64 x86_64 x86_64 GNU/Linux
Machine Type: x86_64-redhat-linux-gnu
Bash Version: 4.1
Patch Level: 2
Release Status: release
Description:
When output of trap is piped to another command, say, less or
cat -, it shows only ignored signals.
Repeat-By:
$ trap '' SIGINT
$ trap 'echo hello' SIGHUP
$ trap 'echo foobar' SIGTERM
$ trap | cat -
trap -- '' SIGINT
Expected Result:
$ trap | cat -
trap -- '' SIGINT
trap -- 'echo hello' SIGHUP
trap -- 'echo foobar' SIGTERM
Fix:
I've not looked at how this can be fixed yet, but it looks
like bash is forking for the trap builtin, which inherits the
ignored signals, hence showing only them as active traps
into the pipe. The other signals are not inherited and hence
do not show up at all.
The fix would probably involve either preparing a trap list
before forking for the first pipe process or not fork at all
in case a trap builtin is called. In either case I suspect the
fix will be quite hacky.
As an aside, the same behaviour can be seen on ksh as well as
csh. Only zsh seems to show the trap list correctly to the
pipeline.
Regards,
Siddhesh
--
Siddhesh Poyarekar
http://siddhesh.in
