switch between alias definitions I'm trying to use `alias` command to switch between two definitions (trying to use Rust's `cargo` and Crystal's compiler `crystal` from command line). I have the following in my `~/.bash_profile`: alias c=crystal alias cargo="unalias c; alias c=cargo" alias crystal="unalias c; alias c=crystal" However, when I try to run something like > > c macro.rs in macOS terminal I get > bash: alias: macro.rs: not found What may be the problem here?

Let's see what's happening here:


$ set -x
$ c file
+ unalias c
+ alias c=crystal file
bash: alias: file: not found
$ set +x


So, `c file` is expanded to `unalias c; alias c=crystal file` (via an intermediate expansion to `crystal file`).

`alias c=crystal file` doesn't make sense. What I think you might have wanted is for `crystal file` to be executed.

You might want to rename the aliases that switches the meanings of `c`:


alias usecrystal="alias c=crystal"
alias usecargo="alias c=cargo"


Alternatively, you may protect the command from alias expansion:


alias c="\crystal"
alias crystal="alias c=\crystal"
alias cargo="alias c=\cargo"


Or use `command` (which IMHO looks better):


alias c="command crystal"
alias crystal='alias c="command crystal"'
alias cargo='alias c="command cargo"'


The `command` command also protects from alias expansion.