一个命令中bash中反引号失败的默认值

Question

I am trying to come up with a mechanism to assign a default value to a variable when a command fails. I can't seem to combine them with || or inserting $() inside the 2nd line.

How do I convert this to one command?

MY_COMMAND=$(which somefile)
MY_COMMAND=${MY_COMMAND:-"/usr/local/dev/branch/somefile"}

Answer 1

The following should work in Bash:

MY_VARIABLE="$(which thing || echo 'default')"

As this is using a subshell ( $() syntax), there should be a complete command on each side of the || or symbol. So the second part should echo something.

On the opposite, ${} is used in parameter substitution , and the variable names can't be nested.