--- layout: "docs" page_title: "Commands: Exec" sidebar_current: "docs-commands-exec" description: |- The exec command provides a mechanism for remote execution. For example, this can be used to run the `uptime` command across all machines providing the `web` service. --- # Consul Exec Command: `consul exec` The `exec` command provides a mechanism for remote execution. For example, this can be used to run the `uptime` command across all machines providing the `web` service. Remote execution works by specifying a job, which is stored in the KV store. Agents are informed about the new job using the [event system](/docs/commands/event.html), which propagates messages via the [gossip protocol](/docs/internals/gossip.html). As a result, delivery is best-effort, and there is **no guarantee** of execution. While events are purely gossip driven, remote execution relies on the KV store as a message broker. As a result, the `exec` command will not be able to properly function during a Consul outage. **Verbose output warning:** use care to make sure that your command does not produce a large volume of output. Writes to the KV store for this output go through the Consul servers and the Raft consesnus algorithm, so having a large number of nodes in the cluster flow a large amount of data through the KV store could make the cluster unavailable. ## Usage Usage: `consul exec [options] [-|command...]` The only required option is a command to execute. This is either given as trailing arguments, or by specifying '-'; stdin will be read to completion as a script to evaluate. The list of available flags are: * `-http-addr` - Address to the HTTP server of the agent you want to contact to send this command. If this isn't specified, the command will contact "127.0.0.1:8500" which is the default HTTP address of a Consul agent. * `-datacenter` - Datacenter to query. Defaults to that of agent. In version 0.4, that is the only supported value. * `-prefix` - Key prefix in the KV store to use for storing request data. Defaults to "_rexec". * `-node` - Regular expression to filter nodes which should evaluate the event. * `-service` - Regular expression to filter to only nodes with matching services. * `-tag` - Regular expression to filter to only nodes with a service that has a matching tag. This must be used with `-service`. As an example, you may do "-service mysql -tag slave". * `-wait` - Specifies the period of time in which no agent's respond before considering the job finished. This is basically the quiescent time required to assume completion. This period is not a hard deadline, and the command will wait longer depending on various heuristics. * `-wait-repl` - Period to wait after writing the job specification for replication. This is a heuristic value and enables agents to do a stale read of the job. Defaults to 200msec. * `-verbose` - Enables verbose output. * `-token` - The ACL token to use during requests. This token must have access to the prefix in the KV store as well as exec "write" access for the _rexec event. Defaults to that of the agent.