How does using the tilde work as a shortcut to my home directory?
~
is your home directory.
~foo
is the home directory of user foo
, if such a user exists, or just a directory named ~foo
, if that user doesn't exist.
Hence, in:
scp ~Desktop/Volenteer.png [email protected]:~j0h/b
~Desktop
will expand to home directory of user Desktop
, if such a user exists (and it usually does not), or be just ~Desktop
(a path which usually does not exist either).
In:
scp ~/Desktop/Volenteer.png [email protected]:~/j0h/b
~/j0h
will expand to a directory named j0h
in jay
's home directory, which, again, is unlikely to exist.
It's not ~
and ~/
where the difference occurs, but in ~
and ~foo
.
Additionally, ~
can also be used for directory history navigation:
~-
is the previous working directory (like$OLDPWD
)~+
is the current working directory (like$PWD
)
This is not applicable to scp
, since you don't get to change directories in the middle of an scp
operation.
And if you use pushd
and popd
to maintain a directory stack, ~N
and ~+N
would be the N
th directory in the directory stack, as seen in the output of dirs
. ~-N
would be the N
th directory from the end (counting from zero, in both cases). For example:
$ for i in etc usr var tmp; do pushd /$i; done
/etc ~/.vim
/usr /etc ~/.vim
/var /usr /etc ~/.vim
/tmp /var /usr /etc ~/.vim
$ dirs
/tmp /var /usr /etc ~/.vim
Then, the directories in the stack can be accessed using:
/tmp /var /usr /etc ~/.vim
~0 ~1 ~2 ~3 ~4
~+0 ~+1 ~+2 ~+3 ~+4
~-4 ~-3 ~-2 ~-1 ~-0
~+ ~-
Have a read through of the GNU documentation for Bash Tilde Expansion (as I should have before my first iteration of this answer).
~/Desktop
and ~j0h
are doing fundamentally different things, which explains why ~Desktop
doesn't work:
A plain
~
is substituted for your current$HOME
environment variable, set on login. So~
resolves to/home/oli
for me, and~/Desktop
reads as/home/oli/Desktop
. This is where you see the tilda being used most.~username
resolves to the home of that user, as set in/etc/passwd
. So~oli
resolves to/home/oli
,~j0h
might resolve to/home/j0h
but not neccessarily, your homedir can be anywhere.~not-a-username
doesn't resolve. BecauseDesktop
is not a user,~Desktop
isn't substituted. It is taken literally as a file or path named~Desktop
(which doesn't exist here).
And needless to say, this is all happening remotely (it'd be useless in scp
if it were replaced with local values). This works because Bash won't substitute ~...
if it's preceded by anything but whitespace.
The symbol ~
is used as a shortcut for /home/user
in bash
, so in the case of ~/Desktop/Volenteer.png
it is shorthand for /home/user/Desktop/Volenteer.png
.
So as you can see the /
, as always, shows an new level in the file system hierarchy.