Using ruby in UNIX shell

Question

I have this program in ruby. I won't explain the whole process, but it gave me in the end a string. I'd like to use this string in my shell. For now, I can generate it with ruby mysoft.rb I'd like to use the result's string in a command, for exemple, when I commit with git, with something like this

git commit -m "$generated_string"

I would that the file was install on the computer and be usable by him. With a single command, he could have the generated string, from any directory, like a "normal" command like "ls" for exemple.

I have no idea how to do that ? Should I do a Gem ? Or something else. I'm new in Ruby, so, pretty confused. Thanks a lot.

maerics · Accepted Answer · 2011-07-28 21:50:53Z

2

You are looking for shell command substitution; the syntax depends on which shell you are using. For example, if using bash or csh:

$ git commit -m `ruby mysoft.rb`

The following syntax does the same thing but in bash only:

$ git commit -m $(ruby mysoft.rb)

answered Jul 28, 2011 at 21:50

maerics

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3 Comments

Simon Over a year ago

Not exactly what I'm looking for in fact. I need something that would "install" the file on the computer, and the user could use it with a single command

maerics Over a year ago

@Simon: update your question with more details of what you are trying to do.

glenn jackman Over a year ago

The $() syntax is not just bash only. I believe all modern shells have it and it is recommended by many over the backticks

Casper · Accepted Answer · 2011-07-28 23:58:27Z

2

Change the first line of your program to this:

#!/usr/bin/env ruby

This line tells the shell that ruby should be used to execute this script by default.

Before you can run the script however you need to add the executable bit to the file:

> chmod gou+x mysoft.rb

Now you can type on the command line directly:

> ./mysoft.rb

And ruby will run your program.

If you want to make the command globally available on your machine, for example with the name mysoft, then you need to do this:

> sudo cp mysoft.rb /usr/bin/mysoft

This will install the program in the bin directory of the system. After this whenever you type mysoft anywhere on the machine, your program will run.

answered Jul 28, 2011 at 23:58

Casper

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1 Comment

the Tin Man Over a year ago

For a single user it isn't necessary to copy the file to /usr/bin. Add the file's directory to the path and it will accomplish the same thing. For executables only I use I install them in ~/bin. For system-wide use by all users /usr/local/bin is preferred.

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