Module: Kernel

Defined in:
lib/qbash.rb

Overview

Execute one bash command.

Author

Yegor Bugayenko (yegor256@gmail.com)

Copyright

Copyright © 2024-2025 Yegor Bugayenko

License

MIT

Instance Method Summary collapse

Instance Method Details

#qbash(cmd, stdin: '', env: {}, log: Loog::NULL, accept: [0], both: false, level: Logger::DEBUG) ⇒ String

Execute a single bash command.

For example:

year = qbash('date +%Y')

If exit code is not zero, an exception will be raised.

To escape arguments, use Shellwords.escape() method.

Stderr automatically merges with stdout.

Read this <a href=“github.com/yegor256/qbash”>README</a> file for more details.

Parameters:

  • cmd (String) —

    The command to run, for example echo “Hello, world!”

  • stdin (String) (defaults to: '') —

    The stdin to provide to the command

  • env (Hash) (defaults to: {}) —

    Hash of environment variables

  • log (Loog|IO) (defaults to: Loog::NULL) —

    Logging facility with .debug() method (or $stdout, or nil if should go to /dev/null)

  • accept (Array) (defaults to: [0]) —

    List of accepted exit codes (accepts all if the list is nil)

  • both (Boolean) (defaults to: false) —

    If set to TRUE, the function returns an array (stdout, code)

  • level (Integer) (defaults to: Logger::DEBUG) —

    Logging level (use Logger::DEBUG, Logger::INFO, Logger::WARN, or Logger::ERROR)

Returns:

  • (String) —

    Everything that was printed to the stdout by the command



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# File 'lib/qbash.rb', line 58

def qbash(cmd, stdin: '', env: {}, log: Loog::NULL, accept: [0], both: false, level: Logger::DEBUG)
  env.each { |k, v| raise "env[#{k}] is nil" if v.nil? }
  cmd = cmd.reject { |a| a.nil? || (a.is_a?(String) && a.empty?) }.join(' ') if cmd.is_a?(Array)
  mtd =
    case level
    when Logger::DEBUG
      :debug
    when Logger::INFO
      :info
    when Logger::WARN
      :warn
    when Logger::ERROR
      :error
    else
      raise "Unknown log level #{level}"
    end
  if log.nil?
    # nothing to print
  elsif log.respond_to?(mtd)
    log.__send__(mtd, "+ #{cmd}")
  else
    log.print("+ #{cmd}\n")
  end
  buf = ''
  e = 1
  start = Time.now
  Open3.popen2e(env, "/bin/bash -c #{Shellwords.escape(cmd)}") do |sin, sout, thr|
    sin.write(stdin)
    sin.close
    until sout.eof?
      begin
        ln = sout.gets
      rescue IOError => e
        ln = Backtrace.new(e).to_s
      end
      if log.nil?
        # no logging
      elsif log.respond_to?(mtd)
        log.__send__(mtd, ln)
      else
        log.print("#{ln}\n")
      end
      buf += ln
    end
    e = thr.value.to_i
    if !accept.nil? && !accept.include?(e)
      raise "The command '#{cmd}' failed with exit code ##{e} in #{start.ago}\n#{buf}"
    end
  end
  return [buf, e] if both
  buf
end