• NAME
• DESCRIPTION
• SYNOPSIS
• EXPORTED FUNCTIONS
  • run($command [, $callback], %options)
  • run($command, $arguments, %options)
  • run($command_description, command => $command, %options)
  • can_run($command)
  • sudo

NAME

Rex::Commands::Run - Execute a remote command

DESCRIPTION

With this module you can run a command.

SYNOPSIS

 my $output = run "ls -l";
 sudo "id";

EXPORTED FUNCTIONS

run($command [, $callback], %options)

run($command, $arguments, %options)

This form will execute $command with the given $arguments. $arguments must be an array reference. The arguments will be quoted.

 run "ls", ["-l", "-t", "-r", "-a"];
 run "ls", ["/tmp", "-l"], auto_die => TRUE;

run($command_description, command => $command, %options)

This function will execute the given command and returns the output. In scalar context it returns the raw output as is, and in list context it returns the list of output lines. The exit value of the command is stored in the $? variable.

 task "uptime", "server01", sub {
   say run "uptime";
   run "uptime", sub {
     my ($stdout, $stderr) = @_;
     my $server = Rex::get_current_connection()->{server};
     say "[$server] $stdout\n";
   };
 };

Supported options are:

  cwd             => $path
    sets the working directory of the executed command to $path
  only_if         => $condition_command
    executes the command only if $condition_command completes successfully
  unless          => $condition_command
    executes the command unless $condition_command completes successfully
  only_notified   => TRUE
    queues the command, to be executed upon notification (see below)
  env             => { var1 => $value1, ..., varN => $valueN }
    sets environment variables in the environment of the command
  timeout         => value
    sets the timeout for the command to be run
  auto_die        => TRUE
    die if the command returns with a non-zero exit code
    it can be set globally via the exec_autodie feature flag
  command         => $command_to_run
    if set, run tries to execute the specified command and the first argument
    becomes an identifier for the run block (e.g. to be triggered with notify)
  creates         => $file_to_create
    tries to create $file_to_create upon execution
    skips execution if the file already exists
  continuous_read => $callback
    calls $callback subroutine reference for each line of the command's output,
    passing the line as an argument

Examples:

If you only want to run a command in special cases, you can queue the command and notify it when you want to run it.

 task "prepare", sub {
   run "extract-something",
     command     => "tar -C /foo -xzf /tmp/foo.tgz",
     only_notified => TRUE;

   # some code ...

   notify "run", "extract-something";  # now the command gets executed
 };

If you only want to run a command if another command succeeds or fails, you can use only_if or unless option.

 run "some-command",
   only_if => "ps -ef | grep -q httpd";   # only run if httpd is running

 run "some-other-command",
   unless => "ps -ef | grep -q httpd";    # only run if httpd is not running

If you want to set custom environment variables you can do it like this:

 run "my_command",

    env => {
     env_var_1 => "the value for 1",
     env_var_2 => "the value for 2",
   };

If you want to end the command upon receiving a certain output: run "my_command", end_if_matched => qr/PATTERN/;

can_run($command)

This function checks if a command is in the path or is available. You can specify multiple commands, the first command found will be returned.

 task "uptime", sub {
   if( my $cmd = can_run("uptime", "downtime") ) {
     say run $cmd;
   }
 };

sudo

Run a single command, a code block, or all commands with sudo. You need perl to be available on the remote systems to use sudo.

Depending on your remote sudo configuration, you may need to define a sudo password with sudo_password first:

 sudo_password 'my_sudo_password'; # hardcoding

Or alternatively, since Rexfile is plain perl, you can read the password from terminal at the start:

 use Term::ReadKey;
 
 print 'I need sudo password: ';
 ReadMode('noecho');
 sudo_password ReadLine(0);
 ReadMode('restore');

Similarly, it is also possible to read it from a secret file, database, etc.

You can turn sudo on globally with:

 sudo TRUE; # run _everything_ with sudo

To run only a specific command with sudo, use :

 say sudo 'id';                # passing a remote command directly
 say sudo { command => 'id' }; # passing anonymous hashref
 
 say sudo { command => 'id', user => 'different' }; # run a single command with sudo as different user
 
 # running a single command with sudo as different user, and `cd` to another directory too
 say sudo { command => 'id', user => 'different', cwd => '/home/different' };

Passing an anonymous coderef to sudo allows for running the commands in the sub with sudo:

 sudo sub {
     service 'nginx' => 'restart';
     say run 'id';
 };

Note that some users receive the error sudo: sorry, you must have a tty to run sudo. In this case you have to disable requiretty for this user. You can do this in your sudoers file with the following code:

   Defaults:$username !requiretty

                    cpanm Rex::Commands::Run

                    perl -MCPAN -e shell
                    install Rex::Commands::Run