--- title: Read Source | Juttle Language Reference --- read ==== Reads events or metrics from various remote backends via [adapters supported by Juttle](../adapters/index.md) and emits them into the flowgraph. The read source honors standard parameters as well as adapter-specific options. ``` read [-from moment] [-to moment] [-last duration] [adapter-options] [filter-expression] | ... ``` Parameter | Description | Required? ---------- | ------------- | ---------: `adapter` | Name of the adapter to connect to the backend. | Yes `-from` | Start time, inclusive: stream points whose time stamps are greater than or equal to the specified moment.

See [Time notation in Juttle](../reference/time.md) for syntax information. | Depending on the adapter `-to` | End time, exclusive: stream points whose time stamps are less than the specified moment, which is less than or equal to :now:

See [Time notation in Juttle](../reference/time.md) for syntax information.

:information_source: `Note:` To stream live data only, omit -from and use `-to :end:`. To combine historical and live data, specify a -from value in the past and use `-to :end:`. | Depending on the adapter `-last` | Shorthand syntax for to `-from (:now: - duration) -to :now:`, this specifies a historical time window of the specified duration that ends at the present moment. | No `adapter-options` | Additional `- ` options specific to reading from the chosen backend, handled by the adapter. | See adapter documentation `filter-expression` | A filter expression such as full-text search, field comparisons, or a combination, where multiple terms are joined with AND, OR, or NOT

See [Filtering](../concepts/filtering.md) for a full description. | No :information_source: Some adapters require a time range to be specified in the read with either `-from` / `-to` or `-last` and/or may have additional constraints on the valid time ranges for a read operation. See the adapter documentation for details. _Example_ ``` read influxdb -from :1 hour ago: -to :now: -db 'test' name='cpu' AND host~=/www.*/ | reduce max() by host ```