# Description

rcmd (remote command) is a command line utility written in Ruby for executing the same command on
multiple systems through ssh.  This is done by assigning a host to a
thread and creating the ssh sessions in those threads.

## Features

- Command line switch for setting number of threads to be used at a time. (Default is 4)
- A comma seperated list of hosts piped from another command can be used as the node list.
- Username can be specified.  (Default is root.  Requires valid ssh-key in ~/.ssh)
- Output shows which host the output is from
- Stdout can be suppressed, only allowing for stderr to be shown

## Installation
rcmd is available as a gem and kan be installed with `gem install rcmd`


# Usage Examples

## Help Screen

```bash
Usage: rcmd [options]
    -u, --username username          Username for SSH connections
    -n, --nodes x,y,z                Comma seperated list of nodes. use '-' for a space seperated list piped from another command
    -r, --regexp regex               Use Regex to build host list (ruby regexp)
    -t, --threads threads            Number of threads to run
    -c, --command <command>          Quoted string containing the command to be run
    -q, --quiet                      Suppress stdout of commands.  stderr will still be displayed
    -v, --version                    Print what version of the command is in use
    -D, --debug                      Print debug information
```

## Specifying nodes manually
Specifying a comma seperated list of hosts and timing the total execution time.
```bash 
daibhidh@darkstar:~/$ time rcmd -n node1,node2,node3,node4 -c 'cat /etc/redhat-release'
node2 :: Red Hat Enterprise Linux ComputeNode release 6.8 (Santiago)
node1 :: Red Hat Enterprise Linux ComputeNode release 6.8 (Santiago)
node4 :: Red Hat Enterprise Linux ComputeNode release 6.9 (Santiago)
node3 :: Red Hat Enterprise Linux ComputeNode release 6.9 (Santiago)


real	0m2.749s
user	0m0.272s
sys	    0m0.050s
```

## Piping list of nodes
Using the hammer cli to get a list of hosts from a RedHat Satellite and providing it to rcmd as the node list.
```bash
daibhidh@darkstar:~/$ hammer --output base host list --organization org | awk '/Name:/ {print $2}' | rcmd -n - -c 'cat /etc/redhat-release'
node1.example.com :: Red Hat Enterprise Linux ComputeNode release 6.8 (Santiago)
node3.example.com :: Red Hat Enterprise Linux ComputeNode release 6.9 (Santiago)
node2.example.com :: Red Hat Enterprise Linux ComputeNode release 6.8 (Santiago)
node4.example.com :: Red Hat Enterprise Linux ComputeNode release 6.9 (Santiago)
```

## Using regex to build node list
```bash
daibhidh@darkstar:~/$ rcmd -r 'node([1-9]|1[1-2])$' -c 'hostname -f'
node2 :: node2.example.com
node1 :: node1.example.com
node4 :: node4.example.com
node3 :: node3.example.com
node5 :: node5.example.com
node6 :: node6.example.com
node8 :: node8.example.com
node7 :: node7.example.com
node11 :: CONNECT ERROR :: Unable to connect to host!
node9 :: node9.example.com
node12 :: node12.example.com
```

# Development

If you are wanting to modify the code by all means do so.  If you clone this repository you can then run `bundle install` to install the dependencies needed.  Tests are performed with *rspec* and can be run with *rake*. 

Available Rake tasks are:

```bash
rake build            # Build rcmd-1.5.5.gem into the pkg directory
rake clean            # Remove any temporary products
rake clobber          # Remove any generated files
rake clobber_rdoc     # Remove RDoc HTML files
rake console          # Open an IRB console with this gem loaded
rake install          # Build and install rcmd-1.5.5.gem into system gems
rake install:local    # Build and install rcmd-1.5.5.gem into system gems without network access
rake rdoc             # Build RDoc HTML files
rake reinstall        # Remove, build, and install gem
rake release[remote]  # Create tag v1.5.5 and build and push rcmd-1.5.5.gem to Rubygems
rake rerdoc           # Rebuild RDoc HTML files
rake spec             # Run RSpec code examples
```