If you wish to execute a command in all running Containers, you can use the following script:
[codesyntax lang="bash"]

for i in `cat /proc/vz/veinfo | awk '{print $1}'|egrep -v '^0$'`; \

do echo "Container $i"; vzctl exec $i <command>; done

[/codesyntax]

where <command> is the command to be executed in all the running Containers. For example:

[codesyntax lang="bash"]
for i in `cat /proc/vz/veinfo | awk '{print $1}'|egrep -v '^0$'`; \

do echo "Container $i"; vzctl exec $i uptime; done
[/codesyntax]

Container 1
2:26pm up 6 days, 1:28, 0 users, load average: 0.00, 0.00, 0.00
Container 101
2:26pm up 6 days, 1:39, 0 users, load average: 0.00, 0.00, 0.00

Source: http://download.swsoft.com/virtuozzo/virtuozzo4.0/docs/en/lin/VzLinuxUG/260.htm

1. Login on openvz node and use ps command to find the PID
[codesyntax lang="bash"]

ssh root@openvz-node
ps auxwwwf

[/codesyntax]

2. After finding PID execute following commands
[codesyntax lang="bash"]

PID=12345
for i in `vzlist -a | grep running | awk '{print $1}'`; do echo $i; ps $* -p $(grep -l "^envID:[[:space:]]*$i\$" /proc/[0-9]*/status | sed -e 's=/proc/\([0-9]*\)/.*=\1=') | grep $PID; done

[/codesyntax]

1. Logon on the machine and execute the following command:

[codesyntax lang="bash"]

cat /proc/vz/veinfo | awk '{print "ID: "$1 " - IP: "$4}'

[/codesyntax]