(R)?ex the friendly automation framework



The Rex-1.9.0 release is now available on CPAN, and it adds a new feature flag to force writing UTF-8 encoded files, documents configuration options, and fixes bugs.


The Rex-1.8.2 release is now available on CPAN, fixing a bug related to task hooks.


The Rex-1.8.1 release is now available on CPAN, improving release automation, packaging, and documentation.


The Rex-1.8.0 release is now available on CPAN, adding initial support to manage Void Linux systems.


The Rex-1.7.1 release is now available on CPAN, fixing a Windows testing issue, and updating some docs.



Need Help?

Rex is a pure open source project, you can find community support in the following places:

Professional support is also available.

» Home » Docs » FAQ


Here we will maintain a list of frequently asked questions with their answers.

Is it called (R)?ex or Rex?

Rex stands for Remote execution. Since automating tasks locally are just as fine as doing the same remotely, (R)?ex is simply a stylized form of (Remote)? execution. Both refers to the same thing: the friendly automation framework.

Why does the run command not format the output?

The run command - called in array context - will return an array.

If you want to print the output to your terminal you have to call it in a scalar context.

my $output = run "df -h";
⁠say $output;

How can I get the current server from within a task?

my $current_server = connection->server;

How can I pass parameters to a task?

⁠task 'mytask', sub {
⁠    my $parameters       = shift;
⁠    my $parameter1_value = $parameters->{parameter1};
⁠    my $parameter2_value = $parameters->{parameter2};

Then you can run mytask from CLI like this:

rex -H hostname mytask --parameter1=value1 --parameter2=value2

How can I run a block of code with one command?

You can use the ShellBlock module. This module can be installed by running:

$ rexify --use Rex::Misc::ShellBlock

Then, you can run your shell code remotely as:

use Rex::Misc::ShellBlock;
⁠task "myexec", sub {
⁠    shell_block <<EOF;    echo "hi"EOF

See the linked documentation page for how to use this module with Perl, Python, or other languages.

How can I run a local script on the remote?

If you have a local script 'files/script', you can run it on the remote using the ShellBlock module referred to in the FAQ above. After you install as pointed out above, you can run the script remotely with the command:

use Rex::Misc::ShellBlock;
⁠task "myexec", sub {
⁠    shell_block template('files/script');

How do I run a local script on the remote under a different user?

Given the same scenario as above, but with the additional requirement to run the script as a different user, the solution looks like below:

use Rex::Misc::ShellBlock;
⁠task "myexec", sub {
⁠    sudo {
⁠        command => sub {
⁠            shell_block template('files/script');
⁠        },
⁠        user => 'root'
⁠    };

How do I check the exit status of a remotely run command?

Rex assigns the exit code from the remote invocation of run or shell_block statements to the $? variable.

How do I use Rex's built-in logger for ERROR/WARN/INFO/DEBUG messages?

Rex::Logger::info("some message"); # for INFO  (green)Rex::Logger::info( "some message", "warn" );  # for WARN  (yellow)Rex::Logger::info( "some message", "error" ); # for ERROR (red)

How do I load all my custom modules easily?

There are plenty of CPAN modules providing this kind of functionality. For a comprehensive list and overview from some time ago, please read Neil Bowers' article about CPAN modules that (can) load other modules.

Since Rex is just Perl, simply use one of them, like Module::Find or Module::Pluggable.

This might affect when modules are loaded (e.g. at compilation time or at runtime), and/or in which order the modules are loaded. If you run into any troubles because of this, please make sure to specify the dependencies of the custom modules correctly.

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