See https://api.slack.com/web#authentication
To get a token see Create and regenerate API tokens
NB: these are now called saved messages.
eg: list starred messages in the order they were starred, most recent first, with 1000 per page:
curl -H 'Authorization: Bearer xoxp-XXXXXXXXXX-XXXXXXXXXXXX-XXXXXXXXXXXX-XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX' https://slack.com/api/stars.list\?count\=1000
To see the channel, text and link, in the order it was posted:
jq -r '.items | sort_by(.message.ts) | .[] | [.channel, .message.text, .message.permalink]' stars.json > stars-text.json
eg: list channel history from a specific ts (inclusive), in order of ts, with user id and message text:
curl -H 'Authorization: Bearer xoxp-XXXXXXXXXX-XXXXXXXXXXXX-XXXXXXXXXXXX-XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX' https://slack.com/api/conversations.history\?channel\=C04G07S1R\&oldest\=1524585770.000886\&inclusive\=true\&limit\=1000 | jq -r '.messages[] | [.user,.text] | @tsv' | tail -r
The channel ID can be found via conversations.list
curl -H 'Authorization: Bearer xoxp-XXXXXXXXXX-XXXXXXXXXXXX-XXXXXXXXXXXX-XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX' https://slack.com/api/conversations.list | jq -r '.channels[] | [.id,.name] | @tsv'
eg: To get the ts of a message you can search messages
curl -H 'Authorization: Bearer xoxp-XXXXXXXXXX-XXXXXXXXXXXX-XXXXXXXXXXXX-XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX' https://slack.com/api/search.messages\?query\=foobar