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In the terminal, one way to reference home is by using ~/. I don't understand how this works, because the output of file ~/ is:

/home/admin/: directory

and just running ~/ results in:

-bash: /home/admin/: Is a directory

so what's converting ~/ into /home/admin?

~/ also appears to work in /bin/dash, so I also know it's not bash specific.

Eliah Kagan
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user8292439
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2 Answers2

15

This is tilde expansion.

Tilde expansion is required by POSIX (see that first linked page) and appears in all modern Bourne-style shells. That includes the popular shells bash, ksh93, and zsh, but also more minimalist shells like mksh, dash, and busybox ash.

In practice, different POSIX-compatible shells sometimes differ in the precise details of tilde expansion, both in the unspecified case that HOME would be used but is unset or empty, and to permit ~ notation to be used for other purposes than expanding users' home directories. For example, tilde expansion in bash also provides a shorthand for accessing the values of the PWD and OLDPWD variables, with ~- and ~+, respectively.

However, in the typical cases, it works about the same across Bourne-style shells. These are typical cases (but note that this way of separating them is not official, it's just my way of presenting the material):

  • ~ or ~/ by itself expands to your home directory.
  • ~/ followed by more path components expands to a path starting at your home directory.
  • ~username or ~username/ by itself expands to the home directory of the user whose username is username.
  • ~username/ followed by more path components expands to a path starting at the home directory of the user whose username is username.
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Eliah Kagan
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    It also appears in non-Bourne style shells like tcsh. – jamesqf Apr 24 '18 at 16:59
  • May be also worth noting that username indicates not just actual human but also system users, and may come from database other than just passwd. See https://unix.stackexchange.com/q/423962/85039 – Sergiy Kolodyazhnyy May 03 '18 at 15:43
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~ is 'shorthand' for $HOME

~ is a 'shorthand' way to write $HOME in other words your home directory. It works in shells (e.g. bash) and is called 'tilde expansion'.

If you add a trailing slash you imply that you are talking about a directory.

Examples:

$ ls -d ~/
/home/sudodus/
$ ls -d ~
/home/sudodus
$ ls -d $HOME
/home/sudodus

$ sudo -i
[sudo] lösenord för sudodus: 
# ls -d ~/
/root/
# ls -d ~
/root
# exit
logout

$ ls xournal.png
xournal.png

$ LANG=C ls xournal.png/
ls: cannot access 'xournal.png/': Not a directory
sudodus
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