Bash scripting and escaping

Question

I'm having some trouble with this bash script, which I intend to use as a startup script for a web server running nginx+unicorn.

DAEMON='/bin/su - deployer -c "/home/deployer/.rvm/gems/ruby-1.9.3-p125/bin/unicorn -c /home/deployer/apps/myapp/current/config/unicorn.rb -E production -D"'

Error:

/bin/su: invalid option -- 'E'

I need to run the script as the user deployer, but I am uncertain how to pass all my command to /bin/su. I'm sure this is a simple escaping error but after trying several different ways of escaping it but I am just not getting this right. Thanks.

why are you assigning the whole su command chain to a variable? You'll have to use eval "$DAEMON" to get it to work, and everyone hates evaling code, (its a big security risk). Good luck. — shellter
– shellter, Commented Feb 19, 2012 at 18:38
It was the first thing I thought of when I noticed I have to run this init script as the user 'deployer'. Better ways to do it are welcome. — Emil Ahlbäck
– Emil Ahlbäck, Commented Feb 19, 2012 at 19:25
Why is the command in a variable? The implicit suggestion here for a better solution is to not put the command in a variable. See also mywiki.wooledge.org/BashFAQ/050 — tripleee
– tripleee, Commented Feb 19, 2012 at 20:01
@tripleee Ah. I didn't get it. Good idea! In fact, that link right there is what I needed to read all along but never found on my own. Write your comment as an answer and I'll accept it. — Emil Ahlbäck
– Emil Ahlbäck, Commented Feb 20, 2012 at 9:22
@shellter deserves the credit here really. Glad I could help clarify his (?) point, though. — tripleee
– tripleee, Commented Feb 20, 2012 at 13:10

David Costa · Accepted Answer · 2012-02-19 19:35:01Z

2

Try to separate sudo options and command with --

DAEMON='/bin/su - deployer -c -- "/home/deployer/.rvm/gems/ruby-1.9.3-p125/bin/unicorn -c /home/deployer/apps/myapp/current/config/unicorn.rb -E production -D"'

answered Feb 19, 2012 at 19:35

David Costa

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l0b0 · Accepted Answer · 2012-02-20 16:22:08Z

1

There are no variables in the command, so you can simply put it in a function:

daemon() {
    /bin/su - deployer -c "/home/deployer/.rvm/gems/ruby-1.9.3-p125/bin/unicorn -c /home/deployer/apps/myapp/current/config/unicorn.rb -E production -D"
}

answered Feb 20, 2012 at 16:22

l0b0

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