#!/usr/bin/php -q
<?

system("ls");

?>

output
[sono.jalin@www conf]$ ./test.php
sh: 1/ls: No such file or directory

[sono.jalin@www conf]$

list modules :
[sono.jalin@www conf]$ php -m
Running PHP 4.2.3
Zend Engine v1.2.0, Copyright (c) 1998-2002 Zend Technologies

[PHP Modules]
yp
xml
wddx
sysvshm
sysvsem
standard
sockets
shmop
session
pspell
posix
pcre
openssl
ncurses
iconv
gmp
gettext
ftp
exif
domxml
dio
dbx
dba
curl
ctype
calendar
bz2
bcmath
zlib
session mm
mysql
snmp
pdf
gd

[Zend Modules]

information compile php-4.2.3
include 
# Patch to get around a dumb assumption that size_t is always 4 bytes
Patch0: php-4.2.1-64bit-iconv.patch
# Argh! openldap 2.1.x changed it's API! This is needed only for openldap 2.1.x and higher
Patch1: php-4.2.1-ldap-TSRM.patch
# Patch to tweak the default php.ini to something a little more unix like
Patch2: php-4.2.1-php.ini-dist.patch
# Patch to pass in -DUCD_COMPATIBLE to the net-snmp package
Patch3: php-4.2.1-snmp.patch
# Patch to prevent zts being compiled in
Patch7: php-4.2.2-disable-zts.patch

all patch based redhat patch

no gdb backtrace since this php is not core dump or something :)

note : 
php-4.2.2 under my system is working perfectly with command system(), passthru, etc

thx
onOs