Is there a difference when using variables in a Jenkins project between this:
node index.js ${arg}
and this:
node index.js $arg
Where arg is a parameter for the project.
Update: Interesting to note that it's not Jenkins-specific.
I think this question should remain as others may assume it's something to do with Jenkins.
In the context of your Jenkins project, it is not needed, except as a matter of style.
The braces are useful in those cases where the shell may not be able to determine the end of a variable name. For instance, if your variable is named this, then you would need the braces if your command was
echo "${this}isatest"
Also, you need them when you want to take advantage of Bash's Shell Parameter Expansions.
It's actually a standard shell syntax.
It's easier to manipulate variables / concatenate the contents of variables into other variable names. e.g.
${foo}bar
You can also perform additional string manipulation with the {}:
STRING="This is a string"
echo ${STRING// /_}
http://www.tldp.org/LDP/abs/html/string-manipulation.html
I also find variables with {} to read better but that's a personal preference.
Generic answer here: When do we need curly braces in variables using Bash?
