nushell/docs/commands/alias.md
Jörn Zaefferer 0779a46179
docs/commands: add alias.md (#1697)
* docs/commands: add alias.md

* docs/commands/alias: drop reference to bash
2020-05-03 16:49:27 +12:00

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# alias
This command allows you to define shortcuts for other common commands.
The command expects three parameters:
* the name of alias
* the parameters as a space-separated list (`[a b ...]`), can be empty (`[]`)
* the body of the alias as a `{...}` block
## Examples
Define a custom `myecho` command as an alias:
```shell
> alias myecho [msg] { echo $msg }
> myecho "hello world"
hello world
```
Since the parameters are well defined, calling the command with the wrong number of parameters will fail properly:
```shell
> myecho hello world
error: myecho unexpected world
- shell:1:18
1 | myecho hello world
| ^^^^^ unexpected argument (try myecho -h)
```
The suggested help command works!
```shell
> myecho -h
Usage:
> myecho ($msg) {flags}
parameters:
($msg)
flags:
-h, --help: Display this help message
```
## Persistent aliases
Aliases are most useful when they are persistent. For that, add them to your startup config:
```
> config --set [startup ["alias myecho [msg] { echo $msg }"]]
```
This is fine for the first alias, but since it overwrites the startup config, you need a different approach for additional aliases.
To add a 2nd alias:
```
config --get startup | append "alias s [] { git status -sb }" | config --set_into startup
```
This first reads the `startup` config (a table of strings), then appends another alias, then sets the `startup` config with the output of the pipeline.
To make this process easier, you could define another alias:
```
> alias addalias [alias-string] { config --get startup | append $alias-string | config --set_into startup }
```
Then use that to add more aliases:
```
addalias "alias s [] { git status -sb }"
```