So far you have learned how to repeat the last change with the dot command (`.`), to replay actions with macros (`q`), and to store texts in the registers (`"`).
By the way, you may have heard of the term "Ex Commands" before. In this guide, I refer them as command-line commands, but both Ex commands and command-line commands are the same. They are the commands that start with a colon (`:`). In the last chapter, you learned about the substitute command. It was an example of an Ex command. They are called Ex because they originally came from the Ex text editor. I will continue to refer to them as command-line commands in this guide. For a full list of Ex commands, check out `:h ex-cmd-index`.
The `pattern` matches all lines containing that pattern, similar to the pattern in the substitute command. The `command` can be any command-line command. The global command works by executing `command` against each line that matches the `pattern`.
If you have the following expressions:
```
const one = 1;
console.log("one: ", one);
const two = 2;
console.log("two: ", two);
const three = 3;
console.log("three: ", three);
```
To remove all lines containing "console", you can run:
```
:g/console/d
```
Result:
```
const one = 1;
const two = 2;
const three = 3;
```
The global command executes the delete command (`d`) on all lines that match the "console" pattern.
When running the `g` command, Vim makes two scans across the file. On the first run, it scans each line and marks the line that matches the `/console/` pattern. Once all the matching lines are marked, it makes the second run, where it executes the `d` command on the marked lines.
If you want to delete all lines containing "const" instead, run:
The global command uses the same pattern system as the substitute command, so this section will serve as a refresher. Feel free to skip to the next section or read along!
If you have these expressions:
```
const one = 1;
console.log("one: ", one);
const two = 2;
console.log("two: ", two);
const three = 3;
console.log("three: ", three);
```
To delete the lines containing either "one" or "two", run:
```
:g/one\|two/d
```
To delete the lines containing any single digits, run either:
```
:g/[0-9]/d
```
or
```
:g/\d/d
```
If you have the expression:
```
const oneMillion = 1000000;
const oneThousand = 1000;
const one = 1;
```
To match the lines containing between three to six zeroes, run:
-`:1,5g/console/d` matches the string "console" between lines 1 and 5 and deletes them.
-`:,5g/console/d` if there is no address before the comma, then it starts from the current line. It looks for the string "console" between the current line and line 5 and deletes them.
-`:3,g/console/d` if there is no address after the comma, then it ends at the current line. It looks for the string "console" between line 3 and the current line and deletes them.
-`:3g/console/d` if you only pass one address without a comma, it executes the command only on line 3. It looks on line 3 and deletes it if has the string "console".
In addition to numbers, you can also use these symbols as range:
-`.` means the current line. A range of `.,3` means between the current line and line 3.
-`$` means the last line in the file. `3,$` range means between line 3 and the last line.
-`+n` means n lines after the current line. You can use it with `.` or without. `3,+1` or `3,.+1` means between line 3 and the line after the current line.
If you don't give it any range, by default it affects the entire file. This is actually not the norm. Most of Vim's command-line commands run on only the current line if you don't pass it any range. The two notable exceptions are the global (`:g`) and the save (`:w`) commands.
-`/./` is a pattern for "non-empty lines". Recall that the dot (`.`) in regex represents *any character*. It matches the lines with at least one character, so it matches the lines with "const" and "console". It does not match empty lines.
-`normal A;` runs the `:normal` command-line command. `A;` is the normal mode command to insert a ";" at the end of the line.
You can also execute a macro with the global command. A macro is just a normal mode operation, so it is possible to execute a macro with `:normal`. If you have the expressions:
The global command itself is a type of a command-line command, so you can technically run the global command inside a global command.
Given the expressions:
```
const one = 1;
console.log("one: ", one);
const two = 2;
console.log("two: ", two);
const three = 3;
console.log("three: ", three);
```
If you run:
```
:g/console/g/two/d
```
First, `g` will look for the lines containing the pattern "console" and find 3 matches. Then the second `g` will look for the line containing the pattern "two" from those three matches. Finally, it will delete that match.
You can also combine `g` with `v` to find positive and negative patterns. For example:
```
:g/console/v/two/d
```
Instead of looking for the line containing the pattern "two", it will look for the lines *not* containing the pattern "two".
You can change the global command's delimiter like the substitute command. The rules are the same: you can use any single byte character except for alphabets, numbers, `"`, `|`, and `\`.
To delete the lines containing "console":
```
:g@console@d
```
If you are using the substitute command with the global command, you can have two different delimiters:
```
g@one@s+const+let+g
```
Here the global command will look for all lines containing "one". The substitute command will substitute, from those matches, the string "const" with "let".
It spells *"grep"*, the same `grep` from the command line. This is **not** a coincidence. The `g/re/p` command originally came from the Ed Editor, one of the first line text editors. The `grep` command got its name from Ed.
`^` is a pattern for the "beginning of a line". Use `^` to match all lines, including empty lines.
If you need to reverse only a few lines, pass it a range. To reverse the lines between line five to line ten, run:
```
:5,10g/^/m 0
```
To learn more about the move command, check out `:h :move`.
## Aggregating All TODOs
When I code, sometimes I think of a random brilliant ideas. Not wanting to lose concentration, I usually write them down in the file I am editing, for example:
```
const one = 1;
console.log("one: ", one);
// TODO: feed the puppy
const two = 2;
// TODO: feed the puppy automatically
console.log("two: ", two);
const three = 3;
console.log("three: ", three);
// TODO: create a startup selling an automatic puppy feeder
```
It can be hard to keep track of all the created TODOs. Vim has a `:t` (copy) method to copy all matches to an address. To learn more about the copy method, check out `:h :copy`.
To copy all TODOs to the end of the file for easier introspection, run:
```
:g/TODO/t $
```
Result:
```
const one = 1;
console.log("one: ", one);
// TODO: feed the puppy
const two = 2;
// TODO: feed the puppy automatically
console.log("two: ", two);
const three = 3;
console.log("three: ", three);
// TODO: create a startup selling an automatic puppy feeder
// TODO: feed the puppy
// TODO: feed the puppy automatically
// TODO: create a startup selling an automatic puppy feeder
```
Now I can review all the TODOs I created, find a time to do them or delegate them to someone else, and continue to work on my next task.
Another alternative is to use `m`:
```
:g/TODO/m $
```
Result:
```
const one = 1;
console.log("one: ", one);
const two = 2;
console.log("two: ", two);
const three = 3;
console.log("three: ", three);
// TODO: feed the puppy
// TODO: feed the puppy automatically
// TODO: create a startup selling an automatic puppy feeder
```
I can just delete the list once I decided what to do with it.
## Black Hole Delete
Recall from the register chapter that deleted texts are stored inside the numbered registers (granted they are sufficiently large ). Whenever you run `:g/console/d`, Vim stores the deleted lines in the numbered registers. If you delete many lines, you can quickly fill up all the numbered registers. To avoid this, you can always use the black hole register (`"_`) to *not* store your deleted lines into the registers. Run:
```
:g/console/d _
```
By passing `_` after `d`, Vim won't save the deleted lines into any registers.
Normally the global command accepts the following form: `:g/pattern/command`. However, you can also run the global command with the following form: `:g/pattern1/,/pattern2/command`. With this, Vim will apply the `command` within `pattern1` and `pattern2`.
With that in mind, let's break down the command `:g/^$/,/./-1j` according to `:g/pattern1/,/pattern2/command`:
-`/pattern1/` is `/^$/`. It represents an empty line (a line with zero character).
-`/pattern2/` is `/./` with `-1` line modifier. `/./` represents a non-empty line (a line with at least one character). The `-1` means the line above that.
-`command` is `j`, the join command (`:j`). In this context, this global command joins all the given lines.
By the way, if you want to reduce multiple empty lines into no lines, instead of using `,/./-1` as the range for `j` command, just use `,/./` as the range instead:
You can sort them by running `:sort`. If you give it a range, it will sort only the lines within that range. For example, `:3,5sort` sorts only between lines three and five.
This is great! But the command looks complicated. Let's break it down. The command consists of three main parts: the global command pattern, the sort command range, and the sort command.
-`/\[/` is the pattern used by the global command. `\[` looks for a literal "[" string.
`+1,/\]/-1` is the range for the sort command.
- A range can have a starting and an ending addresses. In this case, `+1` is the starting address and `/\]/-1` is the ending address.
-`+1` represents the line after the current line, which is the line that matches the pattern "[" from the global command. `+1` offsets the current line by one line. So in the first match, the range actually starts one line *after* the `const arrayB = [` text.
-`/\]/-1` is the ending address. `\]` represents a literal closing square bracket "]". `-1` offsets it by one line. The ending address is the line above the "]".
`sort` is the sort command-line command. It sorts everything within the given range. Everything after the "[" to the line above "]" is getting sorted.
If you are still confused by the command, do not worry. It took me a long time to grasp it. Take a break, leave the screen, and come back again with a fresh mind.
The global command executes the command-line command against all matching lines. With it, you only need to run a command once and Vim will do the rest for you. To become proficient at the global command, two things are required: a good vocabulary of command-line commands and a knowledge of regular expressions. As you spend more time using Vim, you will naturally learn more command-line commands. A regular expression knowledge will require a more active approach. But once you become comfortable with regular expressions, you will be ahead of many.
Some of the examples here are complicated. Do not be intimidated. Really take your time to understand them. Learn to read the patterns. Make sure you know what each letter in each command represent. Do not give up.
Whenever you need to apply a command in several locations, pause and see if you can use the `g` command. Look for the best command for the job and write a pattern to target as many things at once. Then repeat it until you can do it without thinking. The next time, see if there is even a faster and more efficient way to do it.
Now that you know how powerful the global command is, let's learn how to use the external commands to increase your tool arsenals.
