Table 30. Meta expression specific types ┌──────────────┬─────────────────────────────┐ │Type          │ Description                 │ ├──────────────┼─────────────────────────────┤ │              │                             │ │iface_index   │ Interface index (32 bit     │ │              │ number). Can be specified   │ │              │ numerically or as name of   │ │              │ an existing interface.      │ ├──────────────┼─────────────────────────────┤ │              │                             │ │ifname        │ Interface name (16 byte     │ │              │ string). Does not have to   │ │              │ exist.                      │ ├──────────────┼─────────────────────────────┤ │              │                             │ │iface_type    │ Interface type (16 bit      │ │              │ number).                    │ ├──────────────┼─────────────────────────────┤ │              │                             │ │uid           │ User ID (32 bit number).    │ │              │ Can be specified            │ │              │ numerically or as user      │ │              │ name.                       │ ├──────────────┼─────────────────────────────┤ │              │                             │ │gid           │ Group ID (32 bit number).   │ │              │ Can be specified            │ │              │ numerically or as group     │ │              │ name.                       │ ├──────────────┼─────────────────────────────┤ │              │                             │ │realm         │ Routing Realm (32 bit       │ │              │ number). Can be specified   │ │              │ numerically or as symbolic  │ │              │ name defined in             │ │              │ /etc/iproute2/rt_realms.    │ ├──────────────┼─────────────────────────────┤ │              │                             │ │devgroup_type │ Device group (32 bit        │ │              │ number). Can be specified   │ │              │ numerically or as symbolic  │ │              │ name defined in             │ │              │ /etc/iproute2/group.        │ ├──────────────┼─────────────────────────────┤ │              │                             │ │pkt_type      │ Packet type: host           │ │              │ (addressed to local host),  │ │              │ broadcast (to all),         │ │              │ multicast (to group), other │ │              │ (addressed to another       │ │              │ host).                      │ ├──────────────┼─────────────────────────────┤ │              │                             │ │ifkind        │ Interface kind (16 byte     │ │              │ string). See TYPES in       │ │              │ ip-link(8) for a list.      │ ├──────────────┼─────────────────────────────┤ │              │                             │ │time          │ Either an integer or a date │ │              │ in ISO format. For example: │ │              │ "2019-06-06 17:00". Hour    │ │              │ and seconds are optional    │ │              │ and can be omitted if       │ │              │ desired. If omitted,        │ │              │ midnight will be assumed.   │ │              │ The following three would   │ │              │ be equivalent:              │ │              │ "2019-06-06", "2019-06-06   │ │              │ 00:00" and "2019-06-06      │ │              │ 00:00:00". When an integer  │ │              │ is given, it is assumed to  │ │              │ be a UNIX timestamp.        │ ├──────────────┼─────────────────────────────┤ │              │                             │ │day           │ Either a day of week        │ │              │ ("Monday", "Tuesday",       │ │              │ etc.), or an integer        │ │              │ between 0 and 6. Strings    │ │              │ are matched                 │ │              │ case-insensitively, and a   │ │              │ full match is not expected  │ │              │ (e.g. "Mon" would match     │ │              │ "Monday"). When an integer  │ │              │ is given, 0 is Sunday and 6 │ │              │ is Saturday.                │ ├──────────────┼─────────────────────────────┤ │              │                             │ │hour          │ A string representing an    │ │              │ hour in 24-hour format.     │ │              │ Seconds can optionally be   │ │              │ specified. For example,     │ │              │ 17:00 and 17:00:00 would be │ │              │ equivalent.                 │ └──────────────┴─────────────────────────────┘