# conditions.
## one after another.
```bash
foo; bar # bar will run after foo finishes.
```

## AND.
```bash
foo && bar             # bar will only run if foo succeeded.
foo && { bar1; bar2; } # both will run in foo succeeded.
```

## OR.
```bash
foo || bar             # bar will only run in foo failed.
foo || { bar1; bar2; } # both will run if foo failed.
```

## one at the same time with another.
```bash
foo & bar # they will both run at the same time.
```