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Mixing exec redirection with explicit redirection, unexpected results
From: |
root |
Subject: |
Mixing exec redirection with explicit redirection, unexpected results |
Date: |
Tue, 8 Dec 2009 16:39:21 -0500 |
Configuration Information [Automatically generated, do not change]:
Machine: i686
OS: linux-gnu
Compiler: gcc
Compilation CFLAGS: -DPROGRAM='bash' -DCONF_HOSTTYPE='i686'
-DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='i686-redhat-linux-gnu'
-DCONF_VENDOR='redhat' -DLOCALEDIR='/usr/share/locale' -DPACKAGE='bash' -DSHELL
-DHAVE_CONFIG_H -DRECYCLES_PIDS -I. -I. -I./include -I./lib -D_GNU_SOURCE
-D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -O2 -g -pipe -Wall
-Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector
--param=ssp-buffer-size=4 -m32 -march=i386 -mtune=generic
-fasynchronous-unwind-tables
uname output: Linux enterprise.herffjones.hj-int 2.6.18-128.el5 #1 SMP Wed Dec
17 11:42:39 EST 2008 i686 i686 i386 GNU/Linux
Machine Type: i686-redhat-linux-gnu
Bash Version: 3.2
Patch Level: 25
Release Status: release
Description:
When I use the 'exec' built-in to redirect standard output
for a script, and then also use explicit redirection on
other commands, pointing both to the same output file,
I get unpredictable (but repeatable) results with the output
out of order.
Repeat-By:
The following script:
#!/bin/bash
>/tmp/foo
exec 1>/tmp/foo
echo a
echo B >>/tmp/foo
echo c
echo D >>/tmp/foo
echo e
echo F >>/tmp/foo
...should produce the following contents in /tmp/foo:
a
B
c
D
e
F
...but instead it produces:
a
c
e
F
Fix:
I am at a loss for how to understand this behavior -- sorry,
I can't suggest a fix. :-(
- Mixing exec redirection with explicit redirection, unexpected results,
root <=