There are several ways to choose the filesystems of either the table or the JSON output:

* [Choose between the "normal" ones or all of them](#normality)
* [Select the filesystem containing a specific path](#current-filesystem)
* [Use the rich query syntax of the `--filter` argument](#filter-argument)

# Normality

The default selection of filesystems showcases your storage, avoiding any filesystem which both have no "disk" and aren't remote ones, bound to another filesystem, etc.

![screen](img/rows-standard.png)

Here are the rules of the current heuristics, in order: a filesystem

1. is excluded when it's bound to a previous one
1. is excluded when it's of type `squashfs`
1. is included when it's of type `zfs`
1. is included when it's remote
1. is excluded when no underlying disk was found

To see *all* filesystems of your system, do `lfs --all`:

![screen](img/rows-all.png)

This list can be quite big with virtual file systems, docker use, etc.

# Current filesystem

If you're only interested in the device on which some file is, give the path as argument.

For example, for the current device, use `lfs .`:

![screen](img/rows-current.png)

# Filter argument

The `--filter` argument, shortened in `-f`, lets you specify a constraint, or combine several ones.

A constraint can be related to any [column](../table#all-columns).

You can for example fetch the filesystems with a given type with `lfs -f 'type=xfs'`.

The operators you can apply to a column are the following ones:

|operator|meaning|
|-|-|
|<| lower
|<=| lower or equal
|>| greater
|>=| greater or equal
|<>| different
|=| somehow equal - for example `fs=sda` matches `/dev/sda1`
|==|really equal

You can combine several column conditions with boolean operators `|` (or), `&` (and) and `!` (not) and if needed you can use parenthesis.

For example you may want to select the volumes with not enough space with

```bash
lfs -f 'free<100G | use>75%'
```

Examples:

![screen](img/filters.png)

!!! Note
    Only *normal* filesystems are shown unless you use `-a`. This applies even when you use the `--filter` argument.