How to run one script from another, and capture the output

[John Smith]

I have the following hypothetical script that requires arguments to run.
The command line execution looks like this:

'ruby distance_traveled.rb 60 2.5'

The output would be the following:

'You have traveled a distance of 150 miles.'


How would I run the above execution from inside another script, and
capture the output above (the 150 miles portion at least)?

Thanks in advance!

 

[fkocherga]

I have the following hypothetical script that requires arguments to = run.
The command line execution looks like this:
=20
'ruby distance_traveled.rb 60 2.5'
=20
The output would be the following:
=20
'You have traveled a distance of 150 miles.'
=20
=20
How would I run the above execution from inside another script, and
capture the output above (the 150 miles portion at least)?
=20
Thanks in advance!
--=20
Posted via http://www.ruby-forum.com/.
=20

I've faced an exactly same problem when was testing command line =
utilities, by capturing an output and comparing it with expected one. =
Here is a gem for it:

http://github.com/fkocherga/cmd_line_test=20

You may look on running and capturing code there.=20

 

[Gary Wright]

I have the following hypothetical script that requires arguments to = run.
The command line execution looks like this:
=20
'ruby distance_traveled.rb 60 2.5'
=20
The output would be the following:
=20
'You have traveled a distance of 150 miles.'
=20
=20
How would I run the above execution from inside another script, and
capture the output above (the 150 miles portion at least)?

output =3D `ruby distance_traveled.rb 60 2.5`

The backticks cause the standard output of the command to be captured =
and stored in a Ruby string.


Gary Wright

 

[John Smith]

output = `ruby distance_traveled.rb 60 2.5`

The backticks cause the standard output of the command to be captured
and stored in a Ruby string.


Gary Wright

Thanks so much for that!

One more quick question. If distance_traveled.rb sits in a different
directory than the current script that's calling it, how would I specify
it? For example, say it is in ~project/lib/distance_traveled.rb

Thanks again!

 

[Phillip Gawlowski]

One more quick question. If distance_traveled.rb sits in a different
directory than the current script that's calling it, how would I specify
it? For example, say it is in ~project/lib/distance_traveled.rb

output = `ruby ~project/lib/distance_traveled.rb 60 2.5`

Or perform string interpolation, if you don't want to hardcode anything:
path = "~/project/lib/"
script = "script.rb"
args = "my args"

output = `#{path}#{script} #{args}`

<warning type="security implications in accepting user input" />

 

[Gary Wright]

One more quick question. If distance_traveled.rb sits in a different=20=

directory than the current script that's calling it, how would I = specify=20
it? For example, say it is in ~project/lib/distance_traveled.rb

The command is parsed by the shell so ~project/lib/distance_traveled.rb =
should work or a relative or absolute path of course.

Gary Wright

 

[John Smith]

The command is parsed by the shell so ~project/lib/distance_traveled.rb
should work or a relative or absolute path of course.

Gary Wright

Thanks for the help!

However, I should also add that in the above example,
distance_traveled.rb requires other .rb files sitting in the same lib
directory.

I have no problem running distance_traveled.rb from inside lib. However,
from another directory, when I try to run the program using relative
path (ie. 'ruby ../../lib/distance_traveled.rb'), I get
"distance_traveled.rb:1:in `require': no such file to load -- ", in
reference to the other .rb file(s) in the lib directory.

Any suggestions for this issue? Thanks again!

 

[Gary Wright]

=20
However, I should also add that in the above example,=20
distance_traveled.rb requires other .rb files sitting in the same lib=20=

directory.
=20
I have no problem running distance_traveled.rb from inside lib. = However,=20
from another directory, when I try to run the program using relative=20=

path (ie. 'ruby ../../lib/distance_traveled.rb'), I get=20
"distance_traveled.rb:1:in `require': no such file to load -- ", in=20
reference to the other .rb file(s) in the lib directory.
=20
Any suggestions for this issue? Thanks again!

If the files aren't in standard library locations, you'll want to make =
sure that you name them relative to the source file using something =
like:

require File.join(File.expand_path(File.dirname(__FILE__)), 'otherfile')

This ensures that the require method sees a fully qualified path to =
'otherfile' where 'otherfile' is found relative to the directory =
containing the source file instead of relative to the current working =
directory of the process.


Gary Wright