Why does a range search ":[range]/pattern/action" not work the same way as ":[range]g/pattern/action"?

Question

Can someone explain why range search :[range]/pattern/action does not work the same way as :[range]g/pattern/action?

Also :'a,'b/pattern/action gives a warning that the range is 'backward', even though 'a is less than 'b

Answer 1

In :[range]/pattern/action, the /pattern/ part is actually part of the range.

See :help cmdline-ranges, which includes a full explanation of ranges, including this detail:

The / and ? may be preceded with another address. The search starts from there.

So if you have 5/foo/ it means the first line matching "foo" after line 5, or 'b/bar/ means the first line matching "bar" after mark 'b.

So :'a,'b/pattern/p means print lines from mark 'a to the first line matching /pattern/ after mark 'b.

Note how this is very different from :'a,'bg/pattern/p, where the /pattern/ is not part of the range, but instead it's an argument to the :g command. The :'a,'bg/pattern/p command will print only lines matching /pattern/ inside the range going from line where mark 'a is, to the line where mark 'b is (inclusive.)

Answer 2

"Slash" is not a command for command-line mode. It's a line address. Hence :'a,'b/pattern/ is the same as :'a,/pattern/ That's why.