Module: Babushka::ShellHelpers

Includes:
LogHelpers
Included in:
Asset, Asset, BugReporter, DepDefiner, DepDefiner, GitRepo, GitRepo, PathChecker, PkgHelper, Renderable, Resource, RunHelpers, Source, SystemProfile, SystemProfile, Task
Defined in:
lib/babushka/helpers/shell_helpers.rb

Class Method Summary collapse

Methods included from LogHelpers

debug, deprecated!, log, log_block, log_error, log_ok, log_stderr, log_warn, removed!

Class Method Details

.cmd_dir(cmd_name) ⇒ Object

Return the directory from which the specified command would run if invoked via the PATH. If the command doesn’t appear in the PATH, nil is returned.

For example, on a stock OS X machine:

cmd_dir('ruby')     #=> "/usr/bin"
cmd_dir('babushka') #=> nil

This is a direct implementation because the behaviour and output of ‘which` and `type` vary across different platforms and shells. It’s also faster to not shell out.



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# File 'lib/babushka/helpers/shell_helpers.rb', line 184

def cmd_dir cmd_name
  ENV['PATH'].split(':').detect {|path|
    File.executable? File.join(path, cmd_name.to_s)
  }
end

.current_username ⇒ Object 



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# File 'lib/babushka/helpers/shell_helpers.rb', line 216

def current_username
  require 'etc'
  Etc.getpwuid(Process.euid).name
end

.log_shell(message, *cmd, &block) ⇒ Object

Run a shell command, logging before and after using #log_block, and using a spinner while the command runs. The first argument, message, is the message to print before running the command, and the remaining arguments are identical to those of #shell.

As an example, suppose we called #log_shell as follows:

log_shell('Sleeping for a bit', 'sleep 10')

While the command runs, the log would show

Sleeping for a bit... (without a newline)

The command runs with a /-| spinner that animates each time a line of output is emitted by the command. Once the command terminates, the log would be completed to show

Sleeping for a bit... done.



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# File 'lib/babushka/helpers/shell_helpers.rb', line 205

def log_shell message, *cmd, &block
  opts = cmd.extract_options!
  LogHelpers.log_block message do
    shell(*cmd.dup.push(opts.merge(:spinner => true)), &block)
  end
end

.login_shell(cmd, opts = {}, &block) ⇒ Object

Run cmd in a separate interactive shell. This is useful for running commands that depend on something shell-related that was changed during this run, like changing the user’s shell. It’s also useful for running commands that are only valid on an interactive shell, like rvm-related commands.



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# File 'lib/babushka/helpers/shell_helpers.rb', line 106

def  cmd, opts = {}, &block
  if shell('echo $SHELL').p.basename == 'zsh'
    shell "zsh -i -c '#{cmd}'", opts, &block
  else
    shell "bash -l -c '#{cmd}'", opts, &block
  end
end

.raw_shell(*cmd) ⇒ Object

This method is a shortcut for accessing the results of a shell command without using a block. The method itself returns the shell object that is yielded to the block by #shell. As an example, this shell command:

shell('grep rails Gemfile') {|shell| shell.stdout }.empty?

can be simplified to this:

raw_shell('grep rails Gemfile').stdout.empty?



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# File 'lib/babushka/helpers/shell_helpers.rb', line 97

def raw_shell *cmd
  shell(*cmd) {|s| s }
end

.shell(*cmd, &block) ⇒ Object

Run cmd.

If the command succeeds (i.e. returns 0), its output will be returned with a trailing newline stripped, if there was one. If the command fails (i.e. returns a non-zero value), nil will be returned.

If a block is given, it will be yielded once the command has run, with a Babushka::Shell object as its sole argument. Details of the shell command are contained in this object - see the methods cmd, ok?, result, stdout, and stderr.

Several options can be provided to alter #shell’s behaviour.

<tt>:sudo => true</tt> runs the the command as root. If the command
  contains piping or redirection, a 'sudo su' variant will be used
  instead so that the pipe receiver or redirect targets are also
  included in the sudo.
<tt>:as => 'user'</tt> causes sudo to run as the specified user instead
  of root.
<tt>:sudo => 'user'</tt> is a shortcut that has the same effect as
  <tt>:sudo => true, :as => 'user'</tt>
<tt>:cd</tt> specifies the directory in which the command should run.
  If the path doesn't exist or isn't a directory, an error is raised
  unless the <tt>:create</tt> option is also set.
  To achieve the directory change, the command is rewritten to change
  directory first: `cd #{dir} && #{cmd}`.
<tt>:create</tt> causes the directory specified by the <tt>:cd</tt>
  option to be created if it doesn't already exist.
<tt>:input</tt> can be used to supply input for the shell command. It
  be any object that can be written to an IO with <tt>io << obj</tt>.
  When passed, it will be written to the command's stdin pipe before
  any output is read.
<tt>:spinner => true</tt> When this option is passed, a /-\| spinner
  is printed to stdout, and advanced whenever a line is read on the
  command's stdout or stderr pipes. This is useful for monitoring the
  progress of a long-running command, like a build or an installer.



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# File 'lib/babushka/helpers/shell_helpers.rb', line 43

def shell *cmd, &block
  shell!(*cmd, &block)
rescue Shell::ShellCommandFailed => e
  if cmd.extract_options[:log]
    # Don't log the error if the command already logged
  elsif e.stdout.empty? && e.stderr.empty?
    LogHelpers.log "$ #{e.cmd.join(' ')}".colorize('grey') + ' ' + "#{Logging::CrossChar} shell command failed".colorize('red')
  else
    LogHelpers.log "$ #{e.cmd.join(' ')}", :closing_status => 'shell command failed' do
      LogHelpers.log_error(e.stderr.empty? ? e.stdout : e.stderr)
    end
  end
end

.shell!(*cmd, &block) ⇒ Object

Run cmd via #shell, raising an exception if it doesn’t exit with success.



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# File 'lib/babushka/helpers/shell_helpers.rb', line 71

def shell! *cmd, &block
  opts = cmd.extract_options!
  cmd = cmd.first if cmd.map(&:class) == [Array]

  if opts[:cd]
    if !opts[:cd].p.exists?
      if opts[:create]
        opts[:cd].p.mkdir
      else
        raise Errno::ENOENT, opts[:cd]
      end
    elsif !opts[:cd].p.dir?
      raise Errno::ENOTDIR, opts[:cd]
    end
  end
  shell_method = (opts[:as] || opts[:sudo]) ? :sudo : :shell_cmd
  send shell_method, *cmd.dup.push(opts), &block
end

.shell?(*cmd) ⇒ Boolean

Run cmd, returning true if its exit code was 0.

This is useful to run shell commands whose output isn’t important, but whose exit code is. Unlike #shell, which logs the output of shell commands that exit with non-zero status, #shell? runs silently.

The idea is that #shell is for when you’re interested in the command’s output, and #shell? is for when you’re interested in the exit status.

Returns:

  • (Boolean) 


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# File 'lib/babushka/helpers/shell_helpers.rb', line 65

def shell? *cmd
  shell(*cmd) {|s| s.stdout.chomp if s.ok? }
end

.shell_cmd(*cmd, &block) ⇒ Object 



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# File 'lib/babushka/helpers/shell_helpers.rb', line 212

def shell_cmd *cmd, &block
  Shell.new(*cmd).run(&block)
end

.sudo(*cmd, &block) ⇒ Object

Run cmd via ‘sudo`, bypassing it if possible (i.e. if we’re running as root already, or as the user that was requested).

The return behaviour and block handling of #sudo are identical to that of #shell. In fact, #sudo constructs a sudo command, and then uses #shell internally to run the command.

All the options that can be passed to #shell are valid for #sudo as well. The :sudo and :as options can be ommitted, though, which will cause the command to be run as root. Hence, this sudo call:

sudo('ls')

is equivalent to these two shell calls:

shell('ls', :sudo => true)
shell('ls', :as => 'root')

In the same manner, this sudo call:

sudo('ls', :as => 'ben')

is equivalent to these two shell calls:

shell('ls', :sudo => 'ben')
shell('ls', :as => 'ben')



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# File 'lib/babushka/helpers/shell_helpers.rb', line 134

def sudo *cmd, &block
  opts = cmd.extract_options!
  env = cmd.first.is_a?(Hash) ? cmd.shift : {}

  if cmd.map(&:class) != [String]
    raise ArgumentError, "#sudo commands have to be passed as a single string, not splatted strings or an array, since the `sudo` is composed from strings."
  end

  raw_as = opts[:as] || opts[:sudo] || 'root'
  as = raw_as == true ? 'root' : raw_as
  cmd = cmd.last

  sudo_cmd = if current_username == as
    cmd # Don't sudo if we're already running as the specified user.
  elsif opts[:su] || cmd[' |'] || cmd[' >']
    "sudo su - #{as} -c \"#{cmd.gsub('"', '\"')}\""
  else
    "sudo -u #{as} #{cmd}"
  end

  shell [env, sudo_cmd], opts.discard(:as, :sudo, :su), &block
end

.which(cmd_name) ⇒ Object

This method returns the full path to the specified command in the PATH, if that command appears anywhere in the PATH. If it doesn’t, nil is returned.

For example, on a stock OS X machine:

which('ruby')     #=> "/usr/bin/ruby"
which('babushka') #=> nil

This is roughly equivalent to using ‘which` or `type` on the shell. However, because those commands’ behaviour and output vary across platforms and shells, we instead use the logic in #cmd_dir.



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# File 'lib/babushka/helpers/shell_helpers.rb', line 168

def which cmd_name
  matching_dir = cmd_dir(cmd_name)
  File.join(matching_dir, cmd_name.to_s) unless matching_dir.nil?
end