The Duplicate Line command works fine if I’m on a single line and don’t have anything selected. However when I try to duplicate a selection instead of placing the selected text on a new line it places it at the end of the selection. For instance if I have the following selected:
duplicate this line
and this one as well
it will produce:
duplicate this line
and this one as wellduplicate this line
and this one as well
anyway around this? it’s extremely annoying 
If you select the newline at the end of the second line it’ll act as you ask. Doing an Expand Selection to Line before a Duplicate is one way to do this.
ok cool. why wouldn’t you always do expand to line? it seems like that’s the expected behavior…shouldn’t that just be part of the command?
You can chain the two commands together with a macro and bind the macro to a keybinding if you want.
You can do that but now if I want to run the command twice it’ll grab the next line down.
Original (I’ll select and duplicate the top two lines):
it { should respond_to(:password_digest) }
it { should respond_to(:email) }
it { should be_valid }
After 1st run (This is correct so far):
it { should respond_to(:password_digest) }
it { should respond_to(:email) }
it { should respond_to(:password_digest) }
it { should respond_to(:email) }
it { should be_valid }
After 2nd run (This is not correct. Because we’re expanding the selection to line every time it grabbed the next line down and duplicated it too)
it { should respond_to(:password_digest) }
it { should respond_to(:email) }
it { should respond_to(:password_digest) }
it { should respond_to(:email) }
it { should be_valid }
it { should respond_to(:password_digest) }
it { should respond_to(:email) }
it { should be_valid }
Sorry for the necro but this seemed the most relevant thread about this topic.
Fixed this annoying behavior with this macro:
[
{"command": "expand_selection", "args": {"to": "line"}},
{"command": "duplicate_line"}
]
I saved it in Packages/User/duplicate-lines.sublime-macro.
And then on the keymap file:
{ "keys": ["super+alt+down"], "command": "run_macro_file", "args": {"file": "res://Packages/User/duplicate-lines.sublime-macro"} }