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# 14 Using the dcli Utility

The `dcli` utility executes commands across a group of servers on Oracle Big Data Appliance and returns the output. You use `dcli` in Chapter 7.

This chapter contains the following sections:

- Overview of the dcli Utility

- dcli Syntax

- dcli Return Values

- dcli Examples

## 14.1 Overview of the dcli Utility

The `dcli` utility executes commands on multiple Oracle Big Data Appliance servers using the administrative (eth0) interface to make the connections. You can run the utility from any server.

### 14.1.1 Setting Up Passwordless SSH

The `dcli` utility requires a passwordless Secure Shell (SSH) between the local server and all target servers. You run the `dcli` utility on the local server, and the commands specified in `dcli` execute on the target servers.

Two scripts facilitate the use of SSH on Oracle Big Data Appliance: `setup-root-ssh` and `remove-root-ssh`. These scripts accept two options that are also used by `dcli`:

- `-C`: Targets all the servers in a Hadoop cluster

- `-g`: Targets a user-defined set of servers

See Table 14-1 for details about these options.

Note:

The Mammoth and Mammoth Reconfiguration utilities require remote `root` access. However, Oracle Big Data Appliance does not require it for normal operation.

To set up passwordless SSH for root:

1. Connect to an Oracle Big Data Appliance server using PuTTY or a similar utility. Select an SSH connection type.

2. Log in as `root`.

3. Set up passwordless SSH for `root` across the rack:

       setup-root-ssh

   You see the message "ssh key added" from each server.

4. You can now run any `ssh` command on any server in the rack without entering a password. In addition to `dcli` commands, you can use `scp` to copy files between servers.

5. To remove passwordless SSH from `root`:

       remove-root-ssh

See Also:

Full parameter descriptions of `setup-root-ssh` and `remove-root-ssh`.

### 14.1.2 Basic Use of dcli

This topic identifies some basic options to the `dcli` command. For a complete list of options, see Table 14-1.

#### 14.1.2.1 Getting Help

To see the `dcli` help page, enter the `dcli` command with the `-h` or `--help` options. You can see a description of the commands by entering the `dcli` command with no options.

#### 14.1.2.2 Identifying the Target Servers

You can identify the servers where you want the commands to run either in the command line or in a file. For a list of default target servers, use the `-t` option. To change the target servers for the current command, use the `-c` or `-g` options described in Table 14-1.

You can manually create files with groups of servers to manage together. For example, you might manage servers 5 to 18 together, because they have no special functions like servers 1 to 4.

#### 14.1.2.3 Specifying the Commands

You typically specify a command for execution on the target servers on the command line. However, you can also create a command file for a series of commands that you often use together or for commands with complex syntax. See the `-x` option in Table 14-1.

You can also copy files to the target servers without executing them by using the `-f` option.

#### 14.1.2.4 Controlling the Output Levels

You can request more information with the `-v` option or less information with the `-n` option. You can also limit the number of returned lines with the `--maxlines` option, or replace matching strings with the `-r` option.

Following are examples of various output levels using a simple example: the Linux `date` command.

Note:

The output from only one server (node07) is shown. The syntax in these examples executes the `date` command on all servers.

This is the default output, which lists the server followed by the date.

    # dcli date
    bda1node07-adm.example.com: Tue Feb 14 10:22:31 PST 2012

The minimal output returns `OK` for completed execution:

    # dcli -n date
    OK: ['bda1node07.example.com']

Verbose output provides extensive information about the settings under which the command ran:

    dcli -v dateoptions.nodes: Noneoptions.destfile: Noneoptions.file: Noneoptions.group: dcserversoptions.maxLines: 100000options.listNegatives: Falseoptions.pushKey: Falseoptions.regexp: Noneoptions.sshOptions: Noneoptions.scpOptions: Noneoptions.dropKey: Falseoptions.serializeOps: Falseoptions.userID: rootoptions.verbosity 1options.vmstatOps Noneoptions.execfile: Noneargv: ['/opt/oracle/bda/bin/dcli', '-g', 'dcservers', '-v', 'date']Success connecting to nodes: ['bda1node07.example.com']...entering thread for bda1node07.example.com:execute: /usr/bin/ssh -l root bda1node07.example.com ' date' ...exiting thread for bda1node07.example.com status: 0bda1node07.example.com: Tue Feb 14 10:24:43 PST 2012]

## 14.2 dcli Syntax

    dcli [option] [command]

Parameters

option

  An option described in Table 14-1. You can omit all options to run a command on all servers in the current rack.

command

  Any command that runs from the operating system prompt. If the command contains punctuation marks or special characters, then enclose the command in double quotation marks.

  The backslash (\) is the escape character. Precede the following special characters with a backslash on the command line to prevent interpretation by the shell. The backslash is not needed in a command file. See the `-x` option for information about command files.

  `$` (dollar sign)
  `'` (quotation mark)
  `<` (less than)
  `>` (greater than)
  `( )` (parentheses)

Table 14-1 dcli Options

Option | Description
--- | ---
`-c` `nodes` | Specifies a comma-separated list of Oracle Big Data Appliance servers where the command is executed
`-C` | Uses the list of servers in /opt/oracle/bda/cluster-rack-infiniband as the target. See "Identifying the Target Servers".
`-d` `destfile` | Specifies a target directory or file name for the `-f` option
`-f` `file` | Specifies files to be copied to the user's home directory on the target servers. The files are not executed. See the `-l` option.
`-g` `groupfile` | Specifies a file containing a list of Oracle Big Data Appliance servers where the command is executed. You can use either server names or IP addresses in the file.
`-h`, `--help` | Displays a description of the commands
`-k` | Pushes the `ssh` key to each server's `/root/.ssh/authorized_keys` file. See "Setting Up Passwordless SSH" for an easier alternative.
`-l` `userid` | Identifies the user ID for logging in to another server. The default ID is `root`.
`--maxlines=``maxlines` | Identifies the maximum lines of output displayed from a command executed on multiple servers. The default is 10,000 lines.
`-n` | Abbreviates the output for non-error messages. Only the server name is displayed when a server returns normal output (return code `0`). You cannot use the `-n` and `-r` options together.
`-r` `regexp` | Replaces the output with the server name for lines that match the specified regular expression
`-s` `sshoptions` | Specifies a string of options that are passed to SSH
`--scp=``scpoptions` | Specifies a string of options that are passed to Secure Copy (SCP), when these options are different from sshoptions
`--serial` | Serializes execution over the servers. The default is parallel execution.
`-t` | Lists the target servers
`--unkey` | Drops the keys from the `authorized_key` files of the target servers
`-v` | Displays the verbose version of all messages
`--version` | Displays the `dcli` version number
`--vmstat=VMSTATOPS` | Displays the syntax of the Linux Virtual Memory Statistics utility (`vmstat`). This command returns process, virtual memory, disk, trap, and CPU activity information. To enter a `vmstat` command, enclose its options in quotation marks. For example:
    --vmstat="-a 3 5"
See your Linux documentation for more information about `vmstat`.
`-x` `execfile` | Specifies a command file to be copied to the user's home directory and executed on the target servers. See the `-l` option.

## 14.3 dcli Return Values

- `0`: The command ran successfully on all servers.

- `1`: One or more servers were inaccessible or remote execution returned a nonzero value. A message lists the unresponsive servers. Execution continues on the other servers.

- `2`: A local error prevented the command from executing.

If you interrupt the local `dcli` process, then the remote commands may continue without returning their output or status.

## 14.4 dcli Examples

Following are examples of the `dcli` utility.

This example returns the default list of target servers:

    # dcli -t
    Target nodes: ['bda1node01-adm.example.com', 'bda1node02-adm.example.com', 'bda1node03-adm.example.com', 'bda1node04-adm.example.com', 'bda1node05-adm.example.com', 'bda1node06-adm.example.com', 'bda1node07-adm.example.com', 'bda1node08-adm.example.com', 'bda1node09-adm.example.com']

The next example checks the temperature of all servers:

    # dcli 'ipmitool sunoem cli "show /SYS/T_AMB" | grep value'

    bda1node01-adm.example.com: value = 22.000 degree C
    bda1node02-adm.example.com: value = 22.000 degree C
    bda1node03-adm.example.com: value = 22.000 degree C
    bda1node04-adm.example.com: value = 23.000 degree C
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