Redirect a filehandle from a currently running process.

[zim@host ~]$ ./printlines.pl 
Output line 1
Output line 2
Output line 3
Output line 4

[zim@host ~]$ yes 'Y'|gdb -ex 'p close(1)' -ex 'p creat("/tmp/output.txt",0600)' -ex 'q' -p 22503
GNU gdb Fedora (6.8-23.fc9)
Copyright (C) 2008 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-redhat-linux-gnu".
Attaching to process 22503
Reading symbols from /usr/bin/perl...(no debugging symbols found)...done.
Reading symbols from /usr/lib64/perl5/5.10.0/x86_64-linux-thread-multi/CORE/libperl.so...(no debugging symbols found)...done.
Loaded symbols for /usr/lib64/perl5/5.10.0/x86_64-linux-thread-multi/CORE/libperl.so
Reading symbols from /lib64/libresolv.so.2...(no debugging symbols found)...done.
Loaded symbols for /lib64/libresolv.so.2
Reading symbols from /lib64/libnsl.so.1...(no debugging symbols found)...done.
Loaded symbols for /lib64/libnsl.so.1
Reading symbols from /lib64/libdl.so.2...
(no debugging symbols found)...done.
Loaded symbols for /lib64/libdl.so.2
Reading symbols from /lib64/libm.so.6...(no debugging symbols found)...done.
Loaded symbols for /lib64/libm.so.6
Reading symbols from /lib64/libcrypt.so.1...(no debugging symbols found)...done.
Loaded symbols for /lib64/libcrypt.so.1
Reading symbols from /lib64/libutil.so.1...(no debugging symbols found)...done.
Loaded symbols for /lib64/libutil.so.1
Reading symbols from /lib64/libpthread.so.0...
(no debugging symbols found)...done.
[Thread debugging using libthread_db enabled]
[New Thread 0x7ff25bd046f0 (LWP 22503)]
Loaded symbols for /lib64/libpthread.so.0
Reading symbols from /lib64/libc.so.6...(no debugging symbols found)...done.
Loaded symbols for /lib64/libc.so.6
Reading symbols from /lib64/ld-linux-x86-64.so.2...(no debugging symbols found)...done.
Loaded symbols for /lib64/ld-linux-x86-64.so.2
(no debugging symbols found)
0x00000039f1ca6390 in __nanosleep_nocancel () from /lib64/libc.so.6
$1 = 0
$2 = 1
The program is running.  Quit anyway (and detach it)? (y or n) [answered Y; input not from terminal]
Detaching from program: /usr/bin/perl, process 22503

[zim@host ~]$ cat /tmp/output.txt 
Output line 5
Output line 6
Output line 7
Output line 8
Output line 9
Output line 10