slack-cli Command Reference

channels list

List all channels the user is a member of.

slack-cli channels list [--active-since <datetime>] [--markdown]

Flags:

• --active-since <datetime> — ISO datetime. Only return channels with activity since this time. Checks both new top-level messages and thread replies (a channel counts as active if any thread in it received a new reply, even if the thread started before --active-since).
• --markdown — Human-readable output instead of JSON.

Output fields (JSON):

[
  {
    "id": "C012AB3CD",
    "name": "product",
    "topic": "Product team discussions",
    "purpose": "Roadmap, decisions, and feature work",
    "num_members": 12,
    "last_active": "2026-03-20T10:34:12.000Z"  // null when --active-since not used
  }
]

Example:

# All joined channels
slack-cli channels list --markdown

# Channels active in the last hour
slack-cli channels list --active-since "2026-03-20T09:00:00Z" --markdown

messages list

Fetch messages in a channel since a given datetime — including thread roots with new replies, even when the root was posted before --since. Automatically marks the channel as read up to the latest message fetched.

slack-cli messages list --channel <channel-id> --since <datetime> [--markdown]

Required flags:

• --channel <channel-id> — Slack channel ID (e.g. C012AB3CD)
• --since <datetime> — ISO datetime. Returns:
  • All messages posted after this time
  • Thread roots posted before this time that have received new replies after it (flagged with has_new_replies: true)

Optional flags:

• --markdown — Human-readable output.

Output fields (JSON):

[
  {
    "ts": "1742463252.000001",
    "time": "2026-03-20T10:34:12.000Z",
    "sender": "Alice",
    "text": "Should we move the launch to next week?",
    "is_thread_root": true,
    "reply_count": 4,
    "latest_reply": "2026-03-20T11:02:00.000Z",
    "has_new_replies": true,
    "is_thread_reply": false,
    "thread_ts": null
  }
]

Notes:

• System messages (channel joins, topic changes, etc.) are excluded.
• Messages are returned in chronological order (oldest first).
• When has_new_replies: true, use thread get to fetch the full thread.

Example:

slack-cli messages list --channel C012AB3CD --since "2026-03-20T09:00:00Z" --markdown

messages send

Send a message to a channel or reply in a thread.

slack-cli messages send --channel <channel-id> --text <text> [--thread-id <ts>] [--markdown]

Required flags:

• --channel <channel-id> — Slack channel ID (e.g. C012AB3CD)
• --text <text> — message body

Optional flags:

• --thread-id <ts> — reply in a thread by passing the parent message's ts (Slack uses ts as the thread ID)
• --markdown — Human-readable confirmation instead of JSON.

Output fields (JSON):

{
  "ok": true,
  "channel": "C012AB3CD",
  "ts": "1742463300.000001",
  "thread_ts": "1742463252.000001"  // only present when replying in a thread
}

Error handling: If the Slack token doesn't have the chat:write scope, the CLI exits with a clear error. This means you don't have permission to send messages — do not treat it as a fatal failure.

Example:

# Post to a channel
slack-cli messages send --channel C012AB3CD --text "Heads up: deploy starting now"

# Reply in a thread
slack-cli messages send --channel C012AB3CD --text "Done!" --thread-id 1742463252.000001

thread get

Fetch the full thread for a given message — the parent message plus all replies. Automatically marks the channel as read up to the latest message in the thread.

slack-cli thread get --channel <channel-id> --id <message-id> [--markdown]

Required flags:

• --channel <channel-id> — Slack channel ID where the thread lives
• --id <message-id> — the ID of the parent (root) message. Use the ts field from messages list for any message where is_thread_root: true. Note: in Slack's API, ts is the unique message identifier — it looks like a Unix timestamp but is used as an opaque ID. There is no separate "id" field.

Optional flags:

• --markdown — Human-readable output.

Output fields (JSON):

{
  "channel": "C012AB3CD",
  "thread_id": "1742463252.000001",
  "message_count": 5,
  "messages": [
    {
      "ts": "1742463252.000001",
      "time": "2026-03-20T10:34:12.000Z",
      "sender": "Alice",
      "text": "Should we move the launch to next week?",
      "is_parent": true
    },
    {
      "ts": "1742463300.000001",
      "time": "2026-03-20T10:35:00.000Z",
      "sender": "Bob",
      "text": "Yes, the integration isn't ready.",
      "is_parent": false
    }
  ]
}

Example:

slack-cli thread get --channel C012AB3CD --id 1742463252.000001 --markdown

search

Search messages across all accessible channels.

slack-cli search --query <string> [--count <n>] [--page <n>] [--markdown]

Required flags:

• --query <string> — search query (supports Slack search modifiers like in:#channel, from:@user)

Optional flags:

• --count <n> — results per page (default: 20)
• --page <n> — 1-indexed page number for paginating through results (default: 1)
• --markdown — Human-readable output.

Example:

slack-cli search --query "launch date" --count 10 --markdown
slack-cli search --query "in:#product decision" --markdown
# Fetch the next page of results
slack-cli search --query "launch date" --count 10 --page 2 --markdown

channels mark-read

Mark a channel as read up to a given timestamp. This is called automatically after messages list and thread get — you usually don't need to call it directly. Do not call this manually in automated check-in workflows; only use it when explicitly asked.

slack-cli channels mark-read --channel <channel-id> --until <timestamp> [--markdown]

Required flags:

• --channel <channel-id> — Slack channel ID
• --until <timestamp> — mark as read up to this Slack timestamp (the ts of the last message processed)

Example:

slack-cli channels mark-read --channel C012AB3CD --until 1742463252.000001