What does "cd &" mean?
7. How to create directory and switch to it using single command. As you might already know, the && operator is used for executing multiple commands, and $_ expands to the last argument of the previous command.
Quickly, if you want, you can create a directory and also move to that directory by using a single command. To do this, run the following command:
$ mkdir [dir-name] && cd $_
For those coming from Udacity's Version Control with Git, HowToForge offers a great explanation, here.
$_
expands to the last argument to the previous simple command* or to previous command if it had no arguments.
mkdir my-new-project && cd $_
^ Here you have a command made of two simple commands. The last argument to the first one is my-new-project
so $_
in the second simple command will expand to my-new-project
.
To give another example:
echo a b; echo $_
#Will output:
#a b
#b
In any case, mkdir some_dir && cd $_
is a very common combo. If you get tired of typing it, I think it's a good idea to make it a function:
mkdircd() {
#Make path for each argument and cd into the last path
mkdir -p "$@" && cd "$_"
}
*
The bash manual defines a simple command as "a sequence of optional variable assignments followed by blank-separated words and redirections, and terminated by a control operator. " where control operator refers to one of || & && ; ;; ( ) | |& <newline>
.
In practice$_
works like I've described but only with ||
, &&
, ;
, or newline as the control operator.