1. bunyan(1)
  2. bunyan manual
  3. bunyan(1)


bunyan - filter and pretty-print Bunyan log file content


bunyan [OPTIONS]

... | bunyan [OPTIONS]

bunyan [OPTIONS] -p PID


"Bunyan" is a simple and fast a JSON logging library for node.js services, a one-JSON-object-per-line log format, and a bunyan CLI tool for nicely viewing those logs. This man page describes the latter.


A bunyan log file is a stream of JSON objects, optionally interspersed with non-JSON log lines. The primary usage of bunyan(1) is to pretty print, for example:

$ bunyan foo.log          # or `cat foo.log | bunyan
[2012-02-08T22:56:52.856Z]  INFO: myservice/123 on example.com: My message
    extra: multi
[2012-02-08T22:56:54.856Z] ERROR: myservice/123 on example.com: My message

By default the "long" output format is used. Use the -o FORMAT option to emit other formats. E.g.:

$ bunyan foo.log -o short
22:56:52.856Z  INFO myservice: My message
    extra: multi
22:56:54.856Z ERROR myservice: My message

These will color the output if supported in your terminal. See "OUTPUT FORMATS" below.


The bunyan CLI can also be used to filter a bunyan log. Use -l LEVEL to filter by level:

$ bunyan foo.log -l error       # show only 'error' level records
[2012-02-08T22:56:54.856Z] ERROR: myservice/123 on example.com: My message

Use -c COND to filter on a JavaScript expression returning true on the record data. In the COND code, this refers to the record object:

$ bunyan foo.log -c `this.three`     # show records with the 'extra' field
[2012-02-08T22:56:52.856Z]  INFO: myservice/123 on example.com: My message
    extra: multi


-h, --help

Print this help info and exit.


Print version of this command and exit.

-q, --quiet

Don't warn if input isn't valid JSON.

Dtrace options (only on dtrace-supporting platforms):

-p PID, -p NAME
Process bunyan:log-* probes from the process with the given PID. Can be used multiple times, or specify all processes with '*', or a set of processes whose command & args match a pattern with '-p NAME'.

Filtering options:

-l, --level LEVEL

Only show messages at or above the specified level. You can specify level names or numeric values. (See 'Log Levels' below.)

-c COND, --condition COND

Run each log message through the condition and only show those that resolve to a truish value. E.g. -c 'this.pid == 123'.


Suppress all but legal Bunyan JSON log lines. By default non-JSON, and non-Bunyan lines are passed through.

Output options:


Colorize output. Defaults to try if output stream is a TTY.


Force no coloring (e.g. terminal doesn't support it)

-o FORMAT, --output FORMAT

Specify an output format. One of long (the default), short, json, json-N, bunyan (the native bunyan 0-indent JSON output) or inspect.


Shortcut for -o json.

-L, --time local

Display the time field in local time, rather than the default UTC time.


In Bunyan log records, then level field is a number. For the -l|--level argument the level names are supported as shortcuts. In -c|--condition scripts, uppercase symbols like "DEBUG" are defined for convenience.

Level Name      Level Number    Symbol in COND Scripts
trace           10              TRACE
debug           20              DEBUG
info            30              INFO
warn            40              WARN
error           50              ERROR
fatal           60              FATAL


long (default)      The default output. Long form. Colored and "pretty".
                    'req' and 'res' and 'err' fields are rendered specially
                    as an HTTP request, HTTP response and exception
                    stack trace, respectively. For backward compat, the
                    name "paul" also works for this.
short               Like the default output, but more concise. Some
                    typically redundant fields are ellided.
json                JSON output, 2-space indentation.
json-N              JSON output, N-space indentation, e.g. "json-4"
bunyan              Alias for "json-0", the Bunyan "native" format.
inspect             Node.js `util.inspect` output.


On systems that support DTrace (e.g., MacOS, FreeBSD, illumos derivatives like SmartOS and OmniOS), Bunyan will create a DTrace provider (bunyan) that makes available the following probes:


Each of these probes has a single argument: the string that would be written to the log. Note that when a probe is enabled, it will fire whenever the corresponding function is called, even if the level of the log message is less than that of any stream.

See https://github.com/trentm/node-bunyan#dtrace-support for more details and the '-p PID' option above for convenience usage.


Set to a non-empty value to force no output coloring. See '--no-color'.


bunyan is written in JavaScript and requires node.js (node). The project lives at https://github.com/trentm/node-bunyan and is published to npm as "bunyan".


MIT License (see https://github.com/trentm/node-bunyan/blob/master/LICENSE.txt)

node-bunyan is Copyright (c) 2012 Joyent, Inc. Copyright (c) 2012 Trent Mick. All rights reserved.

  1. January 2015
  2. bunyan(1)
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