Here is the list of experiments I performed that shows that <Bar> is treated as literal <Bar> in some commands but it is treated as | in the :command command.
I am trying to understand why or what in the documentation dictates that <Bar> should be treated as | in the :command command.
Case 1: :! and <Bar>
Enter this command-line mode command in Vim:
:!uname <Bar> grep iWe get this error:
/bin/bash: Bar: No such file or directoryThis error occurred because the following shell command was invoked: uname < Bar > grep i and there is no file named Bar to redirect the standard input of uname to.
We see that the string <Bar> was literally sent to the shell.
Case 2: :echo and <Bar>
Enter this command-line mode command in Vim:
:echo 'hi'<Bar> echo 'bye'We get this error:
E121: Undefined variable: BarE15: Invalid expression: 'hi'<Bar> echo 'bye'Once again <Bar> was literally used as argument in the :echo command.
Case 3: :command, :! and <Bar>
Enter these command-line mode commands in Vim:
:command! A !uname <Bar> grep i:AI get this output:
DarwinYou may get Linux in your output.
The argument <Bar> was interpreted as |.
Case 4: :command, :echo and <Bar>
Enter these command-line mode commands in Vim:
:command! A echo 'hi'<Bar> echo 'bye':AWe get this output:
hibyePress ENTER or type command to continueAgain, the argument <Bar> was interpreted as |.
Question
Why is <Bar> treated as 5-character literal argument in case of :!, :echo, etc. but it is treated as | in :command? I searched the documentation but I can't seem to find anything.
The documentation does mention that <Bar> can be treated as | in the :map and some other commands, but it never mentions anything about it being treated as | in the :command command.
Here are some excerpts from the documentation that one can find by entering :helpgrep <Bar>:
This talks about usage of
<Bar>in the:mapcommand. See:help :bar.There is one exception: When the 'b' flag is present in 'cpoptions', with the":map" and ":abbr" commands and friends CTRL-V needs to be used instead of'\'. You can also use "<Bar>" instead. See also |map_bar|.This talks about the usage of many keycodes including
<Bar>in:mapcommand and a few other commands but no mention of the:commandcommand. See:help keycodes.*key-notation* *key-codes* *keycodes* These names for keys are used in the documentation. They can also be used with the ":map" command (insert the key name by pressing CTRL-K and then the key you want the name for). ...<Bslash> backslash \ 92 *backslash* *<Bslash>*<Bar> vertical bar | 124 *<Bar>*<Del> delete 127 ... For mapping, abbreviation and menu commands you can then copy-paste the examples and use them directly. Or type them literally, including the '<' and'>' characters. This does NOT work for other commands, like ":set" and":autocmd"!This one also talks about usage of
<Bar>in the:mapcommand. See:help map-bar.*map_bar* *map-bar* Since the '|' character is used to separate a map command from the next command, you will have to do something special to include a '|' in {rhs}. There are three methods: use works when example ~<Bar> '<' is not in 'cpoptions' :map _l :!ls <Bar> more^M \| 'b' is not in 'cpoptions' :map _l :!ls \| more^M ^V| always, in Vim and Vi :map _l :!ls ^V| more^M (here ^V stands for CTRL-V; to get one CTRL-V you have to type it twice; you cannot use the <> notation "<C-V>" here).Again, this talks about the
:mapcommand only. See:help usr_40.SPECIAL CHARACTERS The ":map" command can be followed by another command. A | character separates the two commands. This also means that a | character can't be used inside a map command. To include one, use <Bar> (five characters). Example:> :map <F8> :write <Bar> !checkin %:S<CR>
How can we explain the treatment of <Bar> as | in the :command command then?
