Re: Substring Expansion does not work as intended

[Greg Wooledge]

On Wed, Aug 20, 2014 at 03:05:48PM +0200, eckard.brauer@gmx.de wrote:
>       "If offset evaluates to a number less than zero, the value is used as 
> an offset from the end of the value of parameter."
> 
> Repeat-By:
>       x="abcdef"; echo "${x:-2}"
>       Expected: ef
>       Got:      abcdef

This is a result of the collision of two different syntaxes.  Bash is
using the ${parameter:-word} ("Use Default Values") syntax here.

There are two ways to work around this:

${x: -2}
${x:(-2)}

Either one of these avoids the :- syntax ambiguity.  I prefer the
parentheses myself.