196

In Bash, # is used to comment the following. How do I make a comment on the Windows command line?

Peter Mortensen
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Tim
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    Possible duplicate of [Which comment style should I use in batch files?](http://stackoverflow.com/questions/12407800/which-comment-style-should-i-use-in-batch-files) – Michael Freidgeim Jan 27 '16 at 01:30
  • For block comments see http://stackoverflow.com/questions/8526946/commenting-multiple-lines-in-dos-batch-file – AjV Jsy Apr 01 '16 at 08:49
  • Possible duplicate of [How to "comment-out" (add comment) in a batch/cmd?](https://stackoverflow.com/questions/11269338/how-to-comment-out-add-comment-in-a-batch-cmd) – jonrsharpe Jan 14 '19 at 20:04

8 Answers8

257

The command you're looking for is rem, short for "remark".

There is also a shorthand version :: that some people use, and this sort of looks like # if you squint a bit and look at it sideways. I originally preferred that variant since I'm a bash-aholic and I'm still trying to forget the painful days of BASIC :-)

Unfortunately, there are situations where :: stuffs up the command line processor (such as within complex if or for statements) so I generally use rem nowadays. In any case, it's a hack, suborning the label infrastructure to make it look like a comment when it really isn't. For example, try replacing rem with :: in the following example and see how it works out:

if 1==1 (
    rem comment line 1
    echo 1 equals 1
    rem comment line 2
)

You should also keep in mind that rem is a command, so you can't just bang it at the end of a line like the # in bash. It has to go where a command would go. For example, the first line below outputs all hello rem a comment but the second outputs the single word hello:

echo hello rem a comment.
echo hello& rem a comment.

The second is two separate commands separated by &, and with no spaces before the & because echo will output those as well. That's not necessarily important for screen output but, if you're redirecting to a file, it may:

echo hello >file          - includes the space.
echo hello>file           - no space.
paxdiablo
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    I knew of REM but was not aware of the `::` syntax. Is it not widely known? – JAB Jun 08 '10 at 15:35
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    Well, I know there's one person that knew of it. And now there's two :-) Maybe I can claim that I doubled the amount of knowledge in the world. FWIW, Rob van der Woude's site is a truly excellent one for batch file (and other) chicanery: http://www.robvanderwoude.com/batchfiles.php – paxdiablo Jun 08 '10 at 23:55
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    [Which comment style should I use in batch files?](http://stackoverflow.com/q/12407800/395857) gives more details about `::`. – Franck Dernoncourt Feb 23 '16 at 01:50
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    To avoid the comment from appearing in the output you can prefix `REM` with an `@`: `@REM Some comment` – Marcono1234 Jul 06 '21 at 15:20
  • @david-rogers [answer](https://stackoverflow.com/a/29853831/5478086) seems more appropriate since it allows comments in the command line. – Herman Autore Jul 21 '22 at 15:24
  • @Herman: Though I already had the use of `&` in the answer (as `rem` is a command), I've expanded on the explanation. – paxdiablo Jul 21 '22 at 23:33
33

Sometimes, it is convenient to add a comment to a command line. For that, you can use "&REM misc comment text" or, now that I know about it, "&:: misc comment text". For example:

REM SET Token="4C6F72656D20697073756D20646F6C6F" &REM This token is for localhost
SET Token="722073697420616D65742C20636F6E73" &REM This token is for production

This makes it easy to keep track of multiple sets of values when doing exploration, tests of concept, etc. This approach works because '&' introduces a new command on the same line.

David Rogers
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31

A comment is produced using the REM command which is short for "Remark".

REM Comment here...
Robin Day
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20

It's "REM".

Example:

REM This is a comment
Peter Mortensen
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masfenix
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19
: this is one way to comment

As a result:

:: this will also work
:; so will this
:! and this
: ***** and so on ***** :
: // even this \\ :

Above styles work outside codeblocks, otherwise:

REM is another way to comment.
Zimba
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9

Lines starting with "rem" (from the word remarks) are comments:

rem comment here
echo "hello"
PeterMmm
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1

Powershell

For powershell, use #:

PS C:\> echo foo # This is a comment
foo
Tom Hale
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0

  1. A single colon without a space after it is enough

  2. Just don't leave comments at the last line in block

Finally, this works:

if 1==1 (
    :comment line 1
    echo 1 equals 1
)
Alexander Gavriliuk
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