How can I retrieve the output of my comand when using rake sh?

Question

I am running a command using sh and need to read the output of that command. e.g.

sh "whoami"

But sh only seems to return true rather than a string containing the output of the whoami command. Does anyone know of a solution?

Answer 1

Just use backquotes to execute the statement:

output = `whoami`

The result will be in the 'output' variable.

Answer 2

There are several ways:

output = `whoami`

#or

output = %x[whoami]

# or using 'system' but in case of errors it's gonna return false

output = system "whoami"

Answer 3

i wasn't sure how to get those other methods to fail on error, so i went with redirection:

sh "mysql --verbose #{connection_options} < #{sql_file} > #{sql_file_output_file}" do |ok, status|
  ok or fail "mysql file failed [#{sql_file}"
end