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¶ ↑

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
 
Database Options
    -C, --create-config              Create template dbconfig file in ~/.rcmd
    -T, --type server-type           Database query on server type
    -H, --host hostname-pattern      Database query on hostname (sql like query)
    -O, --os operating-system        Database query on Operating System string

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¶ ↑

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

Database backend support¶ ↑

The database backend support is provided by ActiveRecord and thus compatible with databases which are supported by ActiveRecord. Currently the ActiveRecord version is locked to 4.0.0 in the Gemspec due to compatibilty issues with RHEL, CentOS, and Mac OSx to name a few.

To set up the database backend run rcmd with the '-C' switch first. This will create a database configuration file in ~/.rcmd named dbconfig.yml. In this file you can specify the adapter, and various other soptions for the database backend. For the queries to work properly, the :host_field: MUST be set so the command knows what column contains the host name.

Two optional fields exist as well, which are type_field and os_field. While these are meant to represent “Server type (I.e. Web, DB, etc) and Operating System Name/version, you can map these to whatever fields you would like to be able to sort by. If these fields are not specified then using the associated command line options will result in a run time error.

To minimize the size and possible issues with various backend adapters, no adapters are listed/installed when installing this Gem. It is up to you to install the correct adapter for the database you are wanting to connect to.

The '-T' and '-O' options use strict matching in their queries where as the '-H' option uses a 'LIKE' query.

Database backend examples¶ ↑

Hostname query (Match all systems whose hostname starts with node and contains at least two additional charectors): bash daibhidh@darkstar:~/$ rcmd -H 'node%_' -c 'hostname -f' node20 :: node20.example.com node10 :: node10.example.com node12 :: node12.example.com node13 :: node13.example.com node15 :: node15.example.com node16 :: node16.example.com node18 :: node18.example.com node17 :: node17.example.com node11 :: node11.example.com node19 :: node19.example.com node14 :: node14.example.com

Type query (Match all hosts listed as web servers): bash daibhidh@darkstar:~/$ rcmd -T 'web' -c 'hostname -f' node11 :: node11.example.com node19 :: node19.example.com node14 :: node14.example.com

OS query (Match all hosts listed as running slackware): bash daibhidh@darkstar:~/$ rcmd -o 'slackware' -c 'hostname -f' node10 :: node10.example.com node12 :: node12.example.com node18 :: node18.example.com node17 :: node17.example.com node11 :: node11.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:

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