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 -O2 -g -pipe
-Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector
--param=ssp-buffer-size=4 -m64 -mtune=generic
uname output: Linux fiber.upc.intranet 2.6.20-1.2320.fc5 #1 SMP Tue Jun 12
18:50:49 EDT 2007 x86_64 x86_64 x86_64 GNU/Linux
Machine Type: x86_64-redhat-linux-gnu
Bash Version: 3.1
Patch Level: 17
Release Status: release
Note: Configuration Information is irrelevant -- same bug in all
versions(3.1-4.0 inclusive)/OSes(linux,tru64)/machines(alpha,i686,x86_64).
Description:
{trap "/external/program" DEBUG} breaks pipelining in some ways. When
trap is set:
1. A | B pipeline sometimes(*) does not run(**) second part and hungs
forever.
sometimes SIGINT(Ctrl+C) revives it, and second part starts.
(*) in my observation it depends on time, 'A' takes to complete --
"small" tasks does not triggers that behaviour.
(**) trap for the "B" part is called, but not the command "B" itself
2. A & B breaks job control
3. (may be not a bug) "$_" no longer contains last arg.
Repeat-By:
[1] ./bash --norc
bash-4.0$ trap /bin/true DEBUG
bash-4.0$ du -xk .. | sort
#either works or hungs until Ctrl+C, depending on size of du's directory
#ps shows 'du', but no 'sort'
[2] ./bash --norc
bash-4.0$ trap /bin/true DEBUG
bash-4.0$ /bin/true & /bin/true
[2] 16217
[2]+ Done /bin/true
bash-4.0$ jobs
[1] Done jobs
bash-4.0$ jobs
[1] Done jobs
