[[cat]] = cat APIs [partintro] -- ["float",id="intro"] == Introduction JSON is great... for computers. Even if it's pretty-printed, trying to find relationships in the data is tedious. Human eyes, especially when looking at a terminal, need compact and aligned text. The cat API aims to meet this need. All the cat commands accept a query string parameter `help` to see all the headers and info they provide, and the `/_cat` command alone lists all the available commands. [float] [[common-parameters]] == Common parameters [float] [[verbose]] === Verbose Each of the commands accepts a query string parameter `v` to turn on verbose output. For example: [source,js] -------------------------------------------------- GET /_cat/master?v -------------------------------------------------- // CONSOLE Might respond with: [source,txt] -------------------------------------------------- id host ip node u_n93zwxThWHi1PDBJAGAg 127.0.0.1 127.0.0.1 u_n93zw -------------------------------------------------- // TESTRESPONSE[s/u_n93zw(xThWHi1PDBJAGAg)?/.+/ _cat] [float] [[help]] === Help Each of the commands accepts a query string parameter `help` which will output its available columns. For example: [source,js] -------------------------------------------------- GET /_cat/master?help -------------------------------------------------- // CONSOLE Might respond with: [source,txt] -------------------------------------------------- id | | node id host | h | host name ip | | ip address node | n | node name -------------------------------------------------- // TESTRESPONSE[s/[|]/[|]/ _cat] NOTE: `help` is not supported if any optional url parameter is used. For example `GET _cat/shards/twitter?help` or `GET _cat/indices/twi*?help` results in an error. Use `GET _cat/shards?help` or `GET _cat/indices?help` instead. [float] [[headers]] === Headers Each of the commands accepts a query string parameter `h` which forces only those columns to appear. For example: [source,js] -------------------------------------------------- GET /_cat/nodes?h=ip,port,heapPercent,name -------------------------------------------------- // CONSOLE Responds with: [source,txt] -------------------------------------------------- 127.0.0.1 9300 27 sLBaIGK -------------------------------------------------- // TESTRESPONSE[s/9300 27 sLBaIGK/\\d+ \\d+ .+/ _cat] You can also request multiple columns using simple wildcards like `/_cat/thread_pool?h=ip,queue*` to get all headers (or aliases) starting with `queue`. [float] [[numeric-formats]] === Numeric formats Many commands provide a few types of numeric output, either a byte, size or a time value. By default, these types are human-formatted, for example, `3.5mb` instead of `3763212`. The human values are not sortable numerically, so in order to operate on these values where order is important, you can change it. Say you want to find the largest index in your cluster (storage used by all the shards, not number of documents). The `/_cat/indices` API is ideal. We only need to tweak two things. First, we want to turn off human mode. We'll use a byte-level resolution. Then we'll pipe our output into `sort` using the appropriate column, which in this case is the eighth one. [source,sh] -------------------------------------------------- % curl '192.168.56.10:9200/_cat/indices?bytes=b' | sort -rnk8 green wiki2 3 0 10000 0 105274918 105274918 green wiki1 3 0 10000 413 103776272 103776272 green foo 1 0 227 0 2065131 2065131 -------------------------------------------------- // NOTCONSOLE If you want to change the <>, use `time` parameter. If you want to change the <>, use `size` parameter. If you want to change the <>, use `bytes` parameter. [float] === Response as text, json, smile, yaml or cbor [source,sh] -------------------------------------------------- % curl 'localhost:9200/_cat/indices?format=json&pretty' [ { "pri.store.size": "650b", "health": "yellow", "status": "open", "index": "twitter", "pri": "5", "rep": "1", "docs.count": "0", "docs.deleted": "0", "store.size": "650b" } ] -------------------------------------------------- // NOTCONSOLE Currently supported formats (for the `?format=` parameter): - text (default) - json - smile - yaml - cbor Alternatively you can set the "Accept" HTTP header to the appropriate media format. All formats above are supported, the GET parameter takes precedence over the header. For example: [source,sh] -------------------------------------------------- % curl '192.168.56.10:9200/_cat/indices?pretty' -H "Accept: application/json" [ { "pri.store.size": "650b", "health": "yellow", "status": "open", "index": "twitter", "pri": "5", "rep": "1", "docs.count": "0", "docs.deleted": "0", "store.size": "650b" } ] -------------------------------------------------- // NOTCONSOLE [float] [[sort]] === Sort Each of the commands accepts a query string parameter `s` which sorts the table by the columns specified as the parameter value. Columns are specified either by name or by alias, and are provided as a comma separated string. By default, sorting is done in ascending fashion. Appending `:desc` to a column will invert the ordering for that column. `:asc` is also accepted but exhibits the same behavior as the default sort order. For example, with a sort string `s=column1,column2:desc,column3`, the table will be sorted in ascending order by column1, in descending order by column2, and in ascending order by column3. [source,sh] -------------------------------------------------- GET _cat/templates?v&s=order:desc,index_patterns -------------------------------------------------- //CONSOLE returns: [source,txt] -------------------------------------------------- name index_patterns order version pizza_pepperoni [*pepperoni*] 2 sushi_california_roll [*avocado*] 1 1 pizza_hawaiian [*pineapples*] 1 -------------------------------------------------- -- include::cat/alias.asciidoc[] include::cat/allocation.asciidoc[] include::cat/count.asciidoc[] include::cat/fielddata.asciidoc[] include::cat/health.asciidoc[] include::cat/indices.asciidoc[] include::cat/master.asciidoc[] include::cat/nodeattrs.asciidoc[] include::cat/nodes.asciidoc[] include::cat/pending_tasks.asciidoc[] include::cat/plugins.asciidoc[] include::cat/recovery.asciidoc[] include::cat/repositories.asciidoc[] include::cat/thread_pool.asciidoc[] include::cat/shards.asciidoc[] include::cat/segments.asciidoc[] include::cat/snapshots.asciidoc[] include::cat/templates.asciidoc[]