目录路径中的Bash变量空间

Question

How can I remove a white space when I use a variable in a directory path. For example, I'm trying to do

alias test='echo /david/$1'

and when I try

test hhh

this produces

/david/ hhh

with a white space before the variable. It seems very simple but I can't find a solution.

Answer 1

alias doesn't do parameter expansion. At all. Use a function instead.

test (){
  echo "/david/$1"
}

Answer 2

man bash :

There is no mechanism for using arguments in the replacement text. If arguments are needed, a shell function should be used (see FUNCTIONS below). [...] For almost every purpose, aliases are superseded by shell functions.

As a part of alias expansion a space is added at the end of the expanded string (otherwise no argument could be added, like alias ll='ls -l' . So ll -a would be expanded to ls -la which would be wrong). So I see no solution to this problem anything else then to use function as Ignacio proposed.

Anyway using test as function or alias is not the best thing to do as it is a bash built-in command (if no aliased or named a function). You can check how a mnemonic will be interpreted using the type bash built-in.

I defined an alias and a function called test :

$ type test
type test
test is aliased to `echo /xxx/'

$ type -a test
type -a test
test is aliased to `echo /xxx/'
test is a function
test () 
{ 
    echo "/yyy/$1"
}
test is a shell builtin
test is /usr/bin/test