{"id":12125,"date":"2019-03-22T11:17:03","date_gmt":"2019-03-22T11:17:03","guid":{"rendered":"http:\/\/www.appservgrid.com\/paw92\/?p=12125"},"modified":"2019-03-22T11:17:03","modified_gmt":"2019-03-22T11:17:03","slug":"using-dsh-distributed-shell-to-run-linux-commands-across-multiple-machines","status":"publish","type":"post","link":"https:\/\/www.appservgrid.com\/paw92\/index.php\/2019\/03\/22\/using-dsh-distributed-shell-to-run-linux-commands-across-multiple-machines\/","title":{"rendered":"Using DSH (Distributed Shell) to Run Linux Commands Across Multiple Machines"},"content":{"rendered":"

Systems Administrators<\/strong>\u00a0know all too well the importance of being able to monitor and administer numerous machines in a short time, and preferably, with as little running around as possible. Whether it is a small cloud environment, or an enormous server cluster, the ability to centrally manage computers is essential.<\/p>\n

\n

\"DSH<\/a><\/p>\n

DSH Run Commands Across Multiple Servers<\/p>\n<\/div>\n

To partly accomplish this, I am going to show you how to use a nifty little tool called\u00a0DSH<\/strong>\u00a0that allows a user to run commands over multiple machines.<\/p>\n

Read Also<\/strong>:\u00a0Pssh \u2013 Execute Commands on Multiple Remote Linux Servers<\/a><\/p>\n

What is DSH?<\/h3>\n

DSH<\/strong>\u00a0is short for \u201cDistributed Shell<\/strong>\u201d or \u201cDancer\u2019s Shell<\/strong>\u201d it is freely available on most major distributions of\u00a0Linux<\/strong>, but can easily be built from source if your distribution does not offer it in its package repository. You can obtain the source at.<\/p>\n

    \n
  1. http:\/\/www.netfort.gr.jp\/~dancer\/software\/dsh.html.en<\/a><\/li>\n<\/ol>\n

    Install DSH (Distributed Shell) in Linux<\/h3>\n

    We are going to assume a\u00a0Debian<\/strong>\u00a0\/\u00a0Ubuntu<\/strong>\u00a0environment for the scope of this tutorial. If you are using another distribution, please substitute the appropriate commands for your package manager.<\/p>\n

    On Debian \/ Ubuntu<\/h5>\n

    First, let\u2019s install the package via\u00a0apt:<\/strong><\/p>\n

    $ sudo apt-get install dsh<\/pre>\n
    On RHEL \/ CentOS \/ Fedora<\/h5>\n
    This method is for those who are not using\u00a0Debian<\/strong>, and want to compile it from source tar balls. First you need to compile \u201clibdshconfig<\/strong>\u201d and install.<\/p>\n
    # wget http:\/\/www.netfort.gr.jp\/~dancer\/software\/downloads\/libdshconfig-0.20.10.cvs.1.tar.gz\r\n# tar xfz libdshconfig*.tar.gz \r\n# cd libdshconfig-*\r\n# .\/configure ; make\r\n# make install<\/pre>\n
    Then compile\u00a0dsh<\/strong>\u00a0and install.<\/p>\n
    # wget http:\/\/www.netfort.gr.jp\/~dancer\/software\/downloads\/dsh-0.22.0.tar.gz\r\n# tar xfz dsh-0.22.0.tar.gz\r\n# cd dsh-*\r\n# .\/configure ; make \r\n# make install<\/pre>\n
    The main configuration file \u201c\/etc\/dsh\/dsh.conf\u201d<\/strong>\u00a0(For\u00a0Debian<\/strong>) and \u201c\/usr\/local\/etc\/dsh.conf<\/strong>\u201d (for\u00a0Red Hat)<\/strong>\u00a0is pretty straightforward, but since\u00a0rsh<\/strong>\u00a0is an unencrypted protocol, we are going to use\u00a0SSH<\/strong>\u00a0as the remote shell. Using the text editor of your choice, find this line:<\/p>\n
    remoteshell =rsh<\/pre>\n
    And change it to:<\/p>\n
    remoteshell =ssh<\/pre>\n
    There are other options you can pass in here, if you choose to do so, and there are plenty of them to find on the\u00a0dsh man page<\/strong>. For now, we are going to accept the defaults and have a look at the next file,\u00a0\/etc\/dsh\/machines.list<\/strong>\u00a0(for\u00a0Debian<\/strong>).<\/p>\n
    For\u00a0Red Hat<\/strong>\u00a0based systems you need to create a file called \u201cmachines.list<\/strong>\u201d in \u201c\/usr\/local\/etc\/<\/strong>\u201d directory.<\/p>\n
    The syntax here is pretty easy. All one has to do is to enter in a machine\u2019s credentials (Hostname<\/strong>,\u00a0IP Address<\/strong>, or\u00a0FQDN<\/strong>) one per line.<\/p>\n
    Note<\/strong>: When accessing more than one machine simultaneously, it would behove you to set up\u00a0key-based password-less SSH<\/a>\u00a0on all of your machines. Not only does this provide ease of access, but security wise, it hardens your machine as well.<\/p>\n
    My \u201c\/etc\/dsh\/machines.list<\/strong>\u201d or \u201c\/usr\/local\/etc\/machines.list<\/strong>\u201d file says:<\/p>\n
    172.16.25.125\r\n172.16.25.126<\/pre>\n
    Once you have entered in the credentials of the machines you wish to access, let\u2019s run a simple command like `uptime<\/strong>` to all of the machines.<\/p>\n
    $ dsh \u2013aM \u2013c uptime<\/pre>\n
    Sample Output<\/h5>\n
    172.16.25.125<\/strong>: 05:11:58 up 40 days, 51 min, 0 users, load average: 0.00, 0.01, 0.05\r\n172.16.25.126<\/strong>: 05:11:47 up 13 days, 38 min, 0 users, load average: 0.00, 0.01, 0.05<\/pre>\n
    So what did this command do?<\/h3>\n
    Pretty simple. First, we ran\u00a0dsh<\/strong>\u00a0and passed the \u201c\u2013a<\/strong>\u201d option to it, which says to send the \u201cuptime<\/strong>\u201d command to \u201cALL<\/strong>\u201d of the machines listed in \u201c\/etc\/dsh\/machines.list<\/strong>\u201c.<\/p>\n
    Next, we specified the \u201c\u2013M<\/strong>\u201d option, which says to return the \u201cmachine name<\/strong>\u201d (specified in \u201c\/etc\/dsh\/machines.list<\/strong>\u201c) along with the output of the uptime command. (Very useful for sorting when running a command on a number of machines.)<\/p>\n
    The \u201c\u2013c<\/strong>\u201d option stands for \u201ccommand to be executed<\/strong>\u201d in this case, \u201cuptime<\/strong>\u201c.<\/p>\n
    DSH<\/strong>\u00a0can also be configured with groups of machines in the \u201c\/etc\/dsh\/groups\/<\/strong>\u201d file, where is a file with a list of machines in the same format as the \u201c\/etc\/dsh\/machines.list<\/strong>\u201d file. When running\u00a0dsh<\/strong>\u00a0on a group, specify the\u00a0groupname<\/strong>\u00a0after the \u201c-g<\/strong>\u201d option.<\/p>\n
    For\u00a0Red Hat<\/strong>\u00a0based systems you need to create a folder called \u201cgroups<\/strong>\u201d in \u201c\/usr\/local\/etc\/<\/strong>\u201d directory. In that \u201cgroups<\/strong>\u201d directory you create a file called \u201ccluster<\/strong>\u201c.<\/p>\n
    For example, run the \u201cw<\/strong>\u201d command on all machines listed in the \u201ccluster<\/strong>\u201d group file \u201c\/etc\/dsh\/groups\/cluster<\/strong>\u201d or \u201c\/usr\/local\/etc\/groups\/cluster<\/strong>\u201c.<\/p>\n
    $ dsh \u2013M \u2013g cluster \u2013c w<\/pre>\n
    DSH<\/strong>\u00a0provides much more flexibility, and this tutorial only scratches the surface. Aside from executing commands,\u00a0DSH<\/strong>\u00a0can be used to transfer files, install software, add routes, and much more.<\/p>\n
    To a\u00a0Systems Administrator<\/strong>\u00a0tasked with the responsibility of a large network, it is invaluable.<\/p>\n
    Source<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"
    Systems Administrators\u00a0know all too well the importance of being able to monitor and administer numerous machines in a short time, and preferably, with as little running around as possible. Whether it is a small cloud environment, or an enormous server cluster, the ability to centrally manage computers is essential. DSH Run Commands Across Multiple Servers … <\/p>\n
    Continue reading “Using DSH (Distributed Shell) to Run Linux Commands Across Multiple Machines”<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-12125","post","type-post","status-publish","format-standard","hentry","category-linux"],"_links":{"self":[{"href":"https:\/\/www.appservgrid.com\/paw92\/index.php\/wp-json\/wp\/v2\/posts\/12125","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.appservgrid.com\/paw92\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.appservgrid.com\/paw92\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.appservgrid.com\/paw92\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.appservgrid.com\/paw92\/index.php\/wp-json\/wp\/v2\/comments?post=12125"}],"version-history":[{"count":1,"href":"https:\/\/www.appservgrid.com\/paw92\/index.php\/wp-json\/wp\/v2\/posts\/12125\/revisions"}],"predecessor-version":[{"id":12126,"href":"https:\/\/www.appservgrid.com\/paw92\/index.php\/wp-json\/wp\/v2\/posts\/12125\/revisions\/12126"}],"wp:attachment":[{"href":"https:\/\/www.appservgrid.com\/paw92\/index.php\/wp-json\/wp\/v2\/media?parent=12125"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.appservgrid.com\/paw92\/index.php\/wp-json\/wp\/v2\/categories?post=12125"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.appservgrid.com\/paw92\/index.php\/wp-json\/wp\/v2\/tags?post=12125"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}