October 14, 1998 BARRIER 1

### NAME

barrier - syncronize a process on a number of machines.

### SYNOPSIS

barrier [-q] [-v] [-h barrier_host] [-k key] [-p port] -s cluster_size

### DESCRIPTION

The barrier command can be used to syncronize execution of various commands. When a barrier is set, it is not released until all the nodes or processes have met the barrier condition. This can be a handy way to make sure slower machines, perform certain tasks before doing something on faster machines that relies on them. The following options are available:

-q
  Turns quiet off, so barrier notifications are sent to the user.

-v
  Prints the version of ClusterIt to the stdout, and exits.

-h
  Specifies a host, which is running barrierd, to connect to for barrier syncronization. Overrides the ```BARRIER_HOST` environment variable.

-k
  Specifies a unique key to syncronize with. A barrier will only synchronize with other barriers that share the same key. Defaults to the string 'barrier'.

-p
  Specifies a port number of a remote barrier daemon to connect to. Defaults to 1933, and overrides the ```BARRIER_PORT` environment variable.

-s
  Sets the size of the cluster. A barrier condition is met, when the number of barrier clients connected to the remote daemon, sharing the same unique key, is equal to this number.

### ENVIRONMENT

barrier utilizes the following environment variables.

```BARRIER_PORT`
  Sets the default remote port to connect to.

```BARRIER_HOST`
  Sets the default remote host to connect to.

### DIAGNOSTICS

Exit status is 0 on successful syncronization. Exit status will be set to 1 if the connection is lost, or the server rejects your connection.

### SEE ALSO

barrierd(1), dsh(1),

### HISTORY

The barrier command appeared in clusterit 1.1.

### AUTHOR

Barrier was written by Tim Rightnour.