Other meanings of `~` (besides `home directory`) in bash

azurvii · 01-30-2011, 11:37 PM

I don't think I'm a newbie anymore, but still sorry that if this is too basic to ask. I failed to find the answer using Google or LQ search. Since the `~` is shown in most PS1 variable, or just could not attract the attention from search engines simply because it's a symbol. And all pages I found introducing bash variables are telling that `~` is your home directory.

But I just came across expressions like

Quote:

~bin
~username

Those are definitely not as simple as `~/` means.

I tried

Code:

echo ~bin
/bin

and

Code:

echo ~backup/
/var/backups/

Can anyone tell me what's going on with `~`?

Big thanks

Dark_Helmet · 01-31-2011, 12:10 AM

No, nothing else. All it means is "home directory."

When you use it like so:

Code:

$ ls -l ~/

It means to list the contents of the home directory for the current user (you).

When you use it like this:

Code:

$ ls -l ~bin

It means to list the contents of the home directory of the user named "bin". This is just a shorthand to refer to another user's home directory.

If you execute this command:

Code:

cat /etc/passwd

I'm certain you will see entries for a user named "bin" and a user named "backup" -- special system accounts. You'll also see their home directories specified in the /etc/passwd output. It should be obvious from the output, but take a look at man passwd if you can't quite figure out the format of the passwd file.

azurvii · 01-31-2011, 12:21 AM

Ah, that makes sense.
And so i think this should work (if i'm in the sudoers

)

Code:

cd ~Dark_Helmet
sudo touch thanks.txt

Dark_Helmet · 01-31-2011, 12:25 AM

Indeed it would

You're quite welcome!