Using an alias inside a function in bash

martindl · 06-08-2011, 09:51 PM

Hi,

I have trouble with using an alias inside a bash function. I would like to ssh into multiple machines by executing:

ssh machine

To achieve this, I put something like the following into my ~/.bashrc:

alias machine='user@machine'

ssh()
{
eval "/usr/bin/ssh $1"
}

When I type

ssh turing

I would expect a prompt for a password. Instead I get

ssh: Could not resolve hostname turing: Name or service not known

which suggests to me that the alias turing does not get expanded. Is it possible to use an alias inside a function? How can I set up my .bashrc so that

ssh machine

does what I want?

Thanks

David the H. · 06-08-2011, 11:55 PM

An alias is a command substitution. But you're trying to use it as a substitution for an argument to another command. It just doesn't work that way, whether in a function or not. In this case a simple variable substitution is what you want to use.

Code:

machine='user@machine'

ssh()
{
command ssh "$1"
}

ssh $machine

Edit: another option is to make the entire function call the alias:

Code:

ssh()
{
command ssh "$1"
}

alias sshmachine='ssh user@machine'

sshmachine

PS: Please use [code][/code] tags around your code, to preserve formatting and to improve readability.

PPS: It's generally recommended to avoid the use of eval whenever possible. In this case it's completely unnecessary, especially since you're giving the complete path to the executable. But if you need to avoid a conflict between the ssh command and the ssh function (or an alias), use the command built-in. I've updated the examples above to demonstrate this.