使用Ruby和命令行工具在ubuntu中更改目录

Question

#!/home/user/.rvm/rubies/ruby-2.0.0-p353/bin/ruby

 case ARGV[0]
        when "apache"
                exec('cd /etc/apach2')
                exec('sudo nano httpd.conf')

        #...
 end

I am trying to make a quick command line tool that will change directories for me with one word.. so from the command line (in ubuntu 12). It tells me it cant cd.. But I try the command myself and it will work just fine.

Answer 1

Ruby's Dir class is your friend for this, check-out the chdir method:

Dir.chdir('/path/to/change/to')

will change Ruby's concept of the current working directory for the time the code is running. Any sub-shells would consider that their starting directory.

You can also pass chdir a block, and all code in that block will assume the new directory, which will then revert to the old one when the block exits:

Dir.chdir('/path/to/change/to') do
  # do some stuff
end

Answer 2

OK, so I did this and it works (I'm on OS X but should be the same):

ARGV[0]
  when "testme"
    system('cd ripple')
    system('ls -al')

    #...
end

calling system('cd ... does not change move you to that directory in the current shell you are executing your .rb file in. So it would make more sense to do:

system('sudo nano /etc/....

all on one line

I tested it with back ticks and it didn't work at all for me.

I tested with exec() and got the expected result, it runs one line and that's it. So exec() could work if you only have one command to run or you chain them all together with &&

exec('ls /etc && sudo nano /etc/....

I would read this: http://rubyquicktips.com/post/5862861056/execute-shell-commands