如何通过 ssh 执行 Bash 别名

Question

Here's what I'm trying to do:

ssh andy@<ip_address> "cat .bash_aliases; sayhello"

Here's what happens:

alias sayhello="echo hello"
bash: sayhello: command not found

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To be more specific about my problem I'm trying to invoke the command
"sudo etherwake -i eth0 <mac_address>" over ssh -- this executes (I think) on my local computer, giving a sudo: unable to resolve host [blabla] error. It seems like any commands that are not standard bash commands are parsed by my local machine.

If that's what's happening, how do I get around it? If not, what is the explanation?

Answer 1

In general this is not a good idea to use aliases in scripts.

Yet I can suggest one way to do it, but bare in mind how unsafe it is.

• It relies on eval ,
• It reads remote files into the shell context.

Here we go.

ssh remote_host "shopt -s expand_aliases ; source ~/.bash_aliases ; eval sayhello"

Explanation:

1. By default alias expansion is enabled only for interactive shells. To turn it on use shopt -s command.

2. You will need to source the aliases into your shell context anyway.

3. Now you are set to use your aliases via the eval command.

Answer 2

Well, it's a pretty messed up hack, but it works:

$ ssh xxx.xxx.158.40 'source aliases; alias'

alias emacs='emacs -nw'
alias l.='ls -d .*'
alias ll='ls -l'
alias sayhello='echo hello'
alias vi='vim'
alias which='alias | /usr/bin/which --tty-only --read-alias --show-dot --show-tilde'

$ ssh xxx.xxx.158.40 'source aliases; $( alias sayhello | sed -e "s/.$//" -e "s/.*=.//" )'

hello

This also works:

ssh xxx.xxx.158.40 "source aliases; \$( alias sayhello | cut -d\' -f2 )"

Answer 3

@ajreal gave a simple solutions in the above comments -- just put what you want to happen in a file, then execute the file.

So I created a file on the host called sayhello.sh (containing only the line echo Hello ), then on my local machine used

ssh andy@<ip_address> "sh sayhello.sh"