Mixing string formatting with system exec

Ruby
1

noob question…

why does this line produce the following result?

%x("%s %s" % [’/usr/bin/touch’, ‘/tmp/test’])

error:
sh: line 0: fg: no job control

i don’t necessarily need to use string formatting or substitution here,
just curious about the result.

thanks.

2

On 26.09.2010 21:26, Nate St.Germain wrote:

just curious about the result.

thanks.

%x is backticks and the contents between brackets are passed unmodified
to the shell:

Robert@babelfish ~
$ ruby19 -e ‘p %x[ls a]’
ls: cannot access a: No such file or directory
“”

Robert@babelfish ~
$ ruby19 -e ‘p %x[“ls a”]’
sh: ls a: command not found
“”

You are essentially doing the same as this:

irb(main):002:0> system ‘"%s %s" % [’/usr/bin/touch’, ‘/tmp/test’]’
sh: line 0: fg: no job control
=> false

You get the same if you call bash as sh directly:

Robert@babelfish ~
$ /bin/sh -c ‘"%s %s"’
/bin/sh: line 0: fg: no job control

Kind regards

robert

3

Robert K. wrote:

%x is backticks and the contents between brackets are passed unmodified
to the shell:

ahh, got it. thanks, robert.