rclone/docs/content/rc.md

title	description	versionIntroduced
Remote Control / API	Remote controlling rclone with its API	v1.40

Remote controlling rclone with its API

If rclone is run with the --rc flag then it starts an HTTP server which can be used to remote control rclone using its API.

You can either use the rc command to access the API or use HTTP directly.

If you just want to run a remote control then see the rcd command.

Supported parameters

--rc

Flag to start the http server listen on remote requests

--rc-addr=IP

IPaddress:Port or :Port to bind server to. (default "localhost:5572")

--rc-cert=KEY

SSL PEM key (concatenation of certificate and CA certificate)

--rc-client-ca=PATH

Client certificate authority to verify clients with

--rc-htpasswd=PATH

htpasswd file - if not provided no authentication is done

--rc-key=PATH

SSL PEM Private key

--rc-max-header-bytes=VALUE

Maximum size of request header (default 4096)

--rc-min-tls-version=VALUE

The minimum TLS version that is acceptable. Valid values are "tls1.0", "tls1.1", "tls1.2" and "tls1.3" (default "tls1.0").

--rc-user=VALUE

User name for authentication.

--rc-pass=VALUE

Password for authentication.

--rc-realm=VALUE

Realm for authentication (default "rclone")

--rc-server-read-timeout=DURATION

Timeout for server reading data (default 1h0m0s)

--rc-server-write-timeout=DURATION

Timeout for server writing data (default 1h0m0s)

--rc-serve

Enable the serving of remote objects via the HTTP interface. This means objects will be accessible at http://127.0.0.1:5572/ by default, so you can browse to http://127.0.0.1:5572/ or http://127.0.0.1:5572/* to see a listing of the remotes. Objects may be requested from remotes using this syntax http://127.0.0.1:5572/[remote:path]/path/to/object

Default Off.

--rc-files /path/to/directory

Path to local files to serve on the HTTP server.

If this is set then rclone will serve the files in that directory. It will also open the root in the web browser if specified. This is for implementing browser based GUIs for rclone functions.

If --rc-user or --rc-pass is set then the URL that is opened will have the authorization in the URL in the http://user:pass@localhost/ style.

Default Off.

--rc-enable-metrics

Enable OpenMetrics/Prometheus compatible endpoint at /metrics.

Default Off.

--rc-web-gui

Set this flag to serve the default web gui on the same port as rclone.

Default Off.

--rc-allow-origin

Set the allowed Access-Control-Allow-Origin for rc requests.

Can be used with --rc-web-gui if the rclone is running on different IP than the web-gui.

Default is IP address on which rc is running.

--rc-web-fetch-url

Set the URL to fetch the rclone-web-gui files from.

Default https://api.github.com/repos/rclone/rclone-webui-react/releases/latest.

--rc-web-gui-update

Set this flag to check and update rclone-webui-react from the rc-web-fetch-url.

Default Off.

--rc-web-gui-force-update

Set this flag to force update rclone-webui-react from the rc-web-fetch-url.

Default Off.

--rc-web-gui-no-open-browser

Set this flag to disable opening browser automatically when using web-gui.

Default Off.

--rc-job-expire-duration=DURATION

Expire finished async jobs older than DURATION (default 60s).

--rc-job-expire-interval=DURATION

Interval duration to check for expired async jobs (default 10s).

--rc-no-auth

By default rclone will require authorisation to have been set up on the rc interface in order to use any methods which access any rclone remotes. Eg operations/list is denied as it involved creating a remote as is sync/copy.

If this is set then no authorisation will be required on the server to use these methods. The alternative is to use --rc-user and --rc-pass and use these credentials in the request.

Default Off.

--rc-baseurl

Prefix for URLs.

Default is root

--rc-template

User-specified template.

Accessing the remote control via the rclone rc command

Rclone itself implements the remote control protocol in its rclone rc command.

You can use it like this

$ rclone rc rc/noop param1=one param2=two
{
	"param1": "one",
	"param2": "two"
}

Run rclone rc on its own to see the help for the installed remote control commands.

JSON input

rclone rc also supports a --json flag which can be used to send more complicated input parameters.

$ rclone rc --json '{ "p1": [1,"2",null,4], "p2": { "a":1, "b":2 } }' rc/noop
{
	"p1": [
		1,
		"2",
		null,
		4
	],
	"p2": {
		"a": 1,
		"b": 2
	}
}

If the parameter being passed is an object then it can be passed as a JSON string rather than using the --json flag which simplifies the command line.

rclone rc operations/list fs=/tmp remote=test opt='{"showHash": true}'

Rather than

rclone rc operations/list --json '{"fs": "/tmp", "remote": "test", "opt": {"showHash": true}}'

Special parameters

The rc interface supports some special parameters which apply to all commands. These start with _ to show they are different.

Running asynchronous jobs with _async = true

Each rc call is classified as a job and it is assigned its own id. By default jobs are executed immediately as they are created or synchronously.

If _async has a true value when supplied to an rc call then it will return immediately with a job id and the task will be run in the background. The job/status call can be used to get information of the background job. The job can be queried for up to 1 minute after it has finished.

It is recommended that potentially long running jobs, e.g. sync/sync, sync/copy, sync/move, operations/purge are run with the _async flag to avoid any potential problems with the HTTP request and response timing out.

Starting a job with the _async flag:

$ rclone rc --json '{ "p1": [1,"2",null,4], "p2": { "a":1, "b":2 }, "_async": true }' rc/noop
{
	"jobid": 2
}

Query the status to see if the job has finished. For more information on the meaning of these return parameters see the job/status call.

$ rclone rc --json '{ "jobid":2 }' job/status
{
	"duration": 0.000124163,
	"endTime": "2018-10-27T11:38:07.911245881+01:00",
	"error": "",
	"finished": true,
	"id": 2,
	"output": {
		"_async": true,
		"p1": [
			1,
			"2",
			null,
			4
		],
		"p2": {
			"a": 1,
			"b": 2
		}
	},
	"startTime": "2018-10-27T11:38:07.911121728+01:00",
	"success": true
}

job/list can be used to show the running or recently completed jobs

$ rclone rc job/list
{
	"jobids": [
		2
	]
}

Setting config flags with _config

If you wish to set config (the equivalent of the global flags) for the duration of an rc call only then pass in the _config parameter.

This should be in the same format as the config key returned by options/get.

For example, if you wished to run a sync with the --checksum parameter, you would pass this parameter in your JSON blob.

"_config":{"CheckSum": true}

If using rclone rc this could be passed as

rclone rc operations/sync ... _config='{"CheckSum": true}'

Any config parameters you don't set will inherit the global defaults which were set with command line flags or environment variables.

Note that it is possible to set some values as strings or integers - see data types for more info. Here is an example setting the equivalent of --buffer-size in string or integer format.

"_config":{"BufferSize": "42M"}
"_config":{"BufferSize": 44040192}

If you wish to check the _config assignment has worked properly then calling options/local will show what the value got set to.

Setting filter flags with _filter

If you wish to set filters for the duration of an rc call only then pass in the _filter parameter.

This should be in the same format as the filter key returned by options/get.

For example, if you wished to run a sync with these flags

--max-size 1M --max-age 42s --include "a" --include "b"

you would pass this parameter in your JSON blob.

"_filter":{"MaxSize":"1M", "IncludeRule":["a","b"], "MaxAge":"42s"}

If using rclone rc this could be passed as

rclone rc ... _filter='{"MaxSize":"1M", "IncludeRule":["a","b"], "MaxAge":"42s"}'

Any filter parameters you don't set will inherit the global defaults which were set with command line flags or environment variables.

Note that it is possible to set some values as strings or integers - see data types for more info. Here is an example setting the equivalent of --buffer-size in string or integer format.

"_filter":{"MinSize": "42M"}
"_filter":{"MinSize": 44040192}

If you wish to check the _filter assignment has worked properly then calling options/local will show what the value got set to.

Assigning operations to groups with _group = value

Each rc call has its own stats group for tracking its metrics. By default grouping is done by the composite group name from prefix job/ and id of the job like so job/1.

If _group has a value then stats for that request will be grouped under that value. This allows caller to group stats under their own name.

Stats for specific group can be accessed by passing group to core/stats:

$ rclone rc --json '{ "group": "job/1" }' core/stats
{
	"speed": 12345
	...
}

Data types

When the API returns types, these will mostly be straight forward integer, string or boolean types.

However some of the types returned by the options/get call and taken by the options/set calls as well as the vfsOpt, mountOpt and the _config parameters.

• Duration - these are returned as an integer duration in nanoseconds. They may be set as an integer, or they may be set with time string, eg "5s". See the options section for more info.
• Size - these are returned as an integer number of bytes. They may be set as an integer or they may be set with a size suffix string, eg "10M". See the options section for more info.
• Enumerated type (such as CutoffMode, DumpFlags, LogLevel, VfsCacheMode - these will be returned as an integer and may be set as an integer but more conveniently they can be set as a string, eg "HARD" for CutoffMode or DEBUG for LogLevel.
• BandwidthSpec - this will be set and returned as a string, eg "1M".

Specifying remotes to work on

Remotes are specified with the fs=, srcFs=, dstFs= parameters depending on the command being used.

The parameters can be a string as per the rest of rclone, eg s3:bucket/path or :sftp:/my/dir. They can also be specified as JSON blobs.

If specifying a JSON blob it should be a object mapping strings to strings. These values will be used to configure the remote. There are 3 special values which may be set:

• type - set to type to specify a remote called :type:
• _name - set to name to specify a remote called name:
• _root - sets the root of the remote - may be empty

One of _name or type should normally be set. If the local backend is desired then type should be set to local. If _root isn't specified then it defaults to the root of the remote.

For example this JSON is equivalent to remote:/tmp

{
    "_name": "remote",
    "_path": "/tmp"
}

And this is equivalent to :sftp,host='example.com':/tmp

{
    "type": "sftp",
    "host": "example.com",
    "_path": "/tmp"
}

And this is equivalent to /tmp/dir

{
    type = "local",
    _ path = "/tmp/dir"
}

Supported commands

{{< rem autogenerated start "- run make rcdocs - don't edit here" >}}

backend/command: Runs a backend command.

This takes the following parameters:

• command - a string with the command name
• fs - a remote name string e.g. "drive:"
• arg - a list of arguments for the backend command
• opt - a map of string to string of options

Returns:

• result - result from the backend command

Example:

rclone rc backend/command command=noop fs=. -o echo=yes -o blue -a path1 -a path2

Returns

{
	"result": {
		"arg": [
			"path1",
			"path2"
		],
		"name": "noop",
		"opt": {
			"blue": "",
			"echo": "yes"
		}
	}
}

Note that this is the direct equivalent of using this "backend" command:

rclone backend noop . -o echo=yes -o blue path1 path2

Note that arguments must be preceded by the "-a" flag

See the backend command for more information.

Authentication is required for this call.

cache/expire: Purge a remote from cache

Purge a remote from the cache backend. Supports either a directory or a file. Params:

• remote = path to remote (required)
• withData = true/false to delete cached data (chunks) as well (optional)

Eg

rclone rc cache/expire remote=path/to/sub/folder/
rclone rc cache/expire remote=/ withData=true

cache/fetch: Fetch file chunks

Ensure the specified file chunks are cached on disk.

The chunks= parameter specifies the file chunks to check. It takes a comma separated list of array slice indices. The slice indices are similar to Python slices: start[:end]

start is the 0 based chunk number from the beginning of the file to fetch inclusive. end is 0 based chunk number from the beginning of the file to fetch exclusive. Both values can be negative, in which case they count from the back of the file. The value "-5:" represents the last 5 chunks of a file.

Some valid examples are: ":5,-5:" -> the first and last five chunks "0,-2" -> the first and the second last chunk "0:10" -> the first ten chunks

Any parameter with a key that starts with "file" can be used to specify files to fetch, e.g.

rclone rc cache/fetch chunks=0 file=hello file2=home/goodbye

File names will automatically be encrypted when the a crypt remote is used on top of the cache.

cache/stats: Get cache stats

Show statistics for the cache remote.

config/create: create the config for a remote.

This takes the following parameters:

• name - name of remote
• parameters - a map of { "key": "value" } pairs
• type - type of the new remote
• opt - a dictionary of options to control the configuration
  • obscure - declare passwords are plain and need obscuring
  • noObscure - declare passwords are already obscured and don't need obscuring
  • nonInteractive - don't interact with a user, return questions
  • continue - continue the config process with an answer
  • all - ask all the config questions not just the post config ones
  • state - state to restart with - used with continue
  • result - result to restart with - used with continue

See the config create command for more information on the above.

Authentication is required for this call.

config/delete: Delete a remote in the config file.

Parameters:

• name - name of remote to delete

See the config delete command for more information on the above.

Authentication is required for this call.

config/dump: Dumps the config file.

Returns a JSON object:

• key: value

Where keys are remote names and values are the config parameters.

See the config dump command for more information on the above.

Authentication is required for this call.

config/get: Get a remote in the config file.

Parameters:

• name - name of remote to get

See the config dump command for more information on the above.

Authentication is required for this call.

config/listremotes: Lists the remotes in the config file.

Returns

• remotes - array of remote names

See the listremotes command for more information on the above.

Authentication is required for this call.

config/password: password the config for a remote.

This takes the following parameters:

• name - name of remote
• parameters - a map of { "key": "value" } pairs

See the config password command for more information on the above.

Authentication is required for this call.

config/providers: Shows how providers are configured in the config file.

Returns a JSON object:

• providers - array of objects

See the config providers command for more information on the above.

Authentication is required for this call.

config/setpath: Set the path of the config file

Parameters:

• path - path to the config file to use

Authentication is required for this call.

config/update: update the config for a remote.

This takes the following parameters:

• name - name of remote
• parameters - a map of { "key": "value" } pairs
• opt - a dictionary of options to control the configuration
  • obscure - declare passwords are plain and need obscuring
  • noObscure - declare passwords are already obscured and don't need obscuring
  • nonInteractive - don't interact with a user, return questions
  • continue - continue the config process with an answer
  • all - ask all the config questions not just the post config ones
  • state - state to restart with - used with continue
  • result - result to restart with - used with continue

See the config update command for more information on the above.

Authentication is required for this call.

core/bwlimit: Set the bandwidth limit.

This sets the bandwidth limit to the string passed in. This should be a single bandwidth limit entry or a pair of upload:download bandwidth.

Eg

rclone rc core/bwlimit rate=off
{
    "bytesPerSecond": -1,
    "bytesPerSecondTx": -1,
    "bytesPerSecondRx": -1,
    "rate": "off"
}
rclone rc core/bwlimit rate=1M
{
    "bytesPerSecond": 1048576,
    "bytesPerSecondTx": 1048576,
    "bytesPerSecondRx": 1048576,
    "rate": "1M"
}
rclone rc core/bwlimit rate=1M:100k
{
    "bytesPerSecond": 1048576,
    "bytesPerSecondTx": 1048576,
    "bytesPerSecondRx": 131072,
    "rate": "1M"
}

If the rate parameter is not supplied then the bandwidth is queried

rclone rc core/bwlimit
{
    "bytesPerSecond": 1048576,
    "bytesPerSecondTx": 1048576,
    "bytesPerSecondRx": 1048576,
    "rate": "1M"
}

The format of the parameter is exactly the same as passed to --bwlimit except only one bandwidth may be specified.

In either case "rate" is returned as a human-readable string, and "bytesPerSecond" is returned as a number.

core/command: Run a rclone terminal command over rc.

This takes the following parameters:

• command - a string with the command name.
• arg - a list of arguments for the backend command.
• opt - a map of string to string of options.
• returnType - one of ("COMBINED_OUTPUT", "STREAM", "STREAM_ONLY_STDOUT", "STREAM_ONLY_STDERR").
  • Defaults to "COMBINED_OUTPUT" if not set.
  • The STREAM returnTypes will write the output to the body of the HTTP message.
  • The COMBINED_OUTPUT will write the output to the "result" parameter.

Returns:

• result - result from the backend command.
  • Only set when using returnType "COMBINED_OUTPUT".
• error - set if rclone exits with an error code.
• returnType - one of ("COMBINED_OUTPUT", "STREAM", "STREAM_ONLY_STDOUT", "STREAM_ONLY_STDERR").

Example:

rclone rc core/command command=ls -a mydrive:/ -o max-depth=1
rclone rc core/command -a ls -a mydrive:/ -o max-depth=1

Returns:

{
	"error": false,
	"result": "<Raw command line output>"
}

OR
{
	"error": true,
	"result": "<Raw command line output>"
}

Authentication is required for this call.

core/gc: Runs a garbage collection.

This tells the go runtime to do a garbage collection run. It isn't necessary to call this normally, but it can be useful for debugging memory problems.

core/group-list: Returns list of stats.

This returns list of stats groups currently in memory.

Returns the following values:

{
	"groups":  an array of group names:
		[
			"group1",
			"group2",
			...
		]
}

core/memstats: Returns the memory statistics

This returns the memory statistics of the running program. What the values mean are explained in the go docs: https://golang.org/pkg/runtime/#MemStats

The most interesting values for most people are:

• HeapAlloc - this is the amount of memory rclone is actually using
• HeapSys - this is the amount of memory rclone has obtained from the OS
• Sys - this is the total amount of memory requested from the OS
  • It is virtual memory so may include unused memory

core/obscure: Obscures a string passed in.

Pass a clear string and rclone will obscure it for the config file:

• clear - string

Returns:

• obscured - string

core/pid: Return PID of current process

This returns PID of current process. Useful for stopping rclone process.

core/quit: Terminates the app.

(Optional) Pass an exit code to be used for terminating the app:

• exitCode - int

core/stats: Returns stats about current transfers.

This returns all available stats:

rclone rc core/stats

If group is not provided then summed up stats for all groups will be returned.

Parameters

• group - name of the stats group (string)

Returns the following values:

{
	"bytes": total transferred bytes since the start of the group,
	"checks": number of files checked,
	"deletes" : number of files deleted,
	"elapsedTime": time in floating point seconds since rclone was started,
	"errors": number of errors,
	"eta": estimated time in seconds until the group completes,
	"fatalError": boolean whether there has been at least one fatal error,
	"lastError": last error string,
	"renames" : number of files renamed,
	"retryError": boolean showing whether there has been at least one non-NoRetryError,
	"speed": average speed in bytes per second since start of the group,
	"totalBytes": total number of bytes in the group,
	"totalChecks": total number of checks in the group,
	"totalTransfers": total number of transfers in the group,
	"transferTime" : total time spent on running jobs,
	"transfers": number of transferred files,
	"transferring": an array of currently active file transfers:
		[
			{
				"bytes": total transferred bytes for this file,
				"eta": estimated time in seconds until file transfer completion
				"name": name of the file,
				"percentage": progress of the file transfer in percent,
				"speed": average speed over the whole transfer in bytes per second,
				"speedAvg": current speed in bytes per second as an exponentially weighted moving average,
				"size": size of the file in bytes
			}
		],
	"checking": an array of names of currently active file checks
		[]
}

Values for "transferring", "checking" and "lastError" are only assigned if data is available. The value for "eta" is null if an eta cannot be determined.

core/stats-delete: Delete stats group.

This deletes entire stats group.

Parameters

• group - name of the stats group (string)

core/stats-reset: Reset stats.

This clears counters, errors and finished transfers for all stats or specific stats group if group is provided.

Parameters

• group - name of the stats group (string)

core/transferred: Returns stats about completed transfers.

This returns stats about completed transfers:

rclone rc core/transferred

If group is not provided then completed transfers for all groups will be returned.

Note only the last 100 completed transfers are returned.

Parameters

• group - name of the stats group (string)

Returns the following values:

{
	"transferred":  an array of completed transfers (including failed ones):
		[
			{
				"name": name of the file,
				"size": size of the file in bytes,
				"bytes": total transferred bytes for this file,
				"checked": if the transfer is only checked (skipped, deleted),
				"timestamp": integer representing millisecond unix epoch,
				"error": string description of the error (empty if successful),
				"jobid": id of the job that this transfer belongs to
			}
		]
}

core/version: Shows the current version of rclone and the go runtime.

This shows the current version of go and the go runtime:

• version - rclone version, e.g. "v1.53.0"
• decomposed - version number as [major, minor, patch]
• isGit - boolean - true if this was compiled from the git version
• isBeta - boolean - true if this is a beta version
• os - OS in use as according to Go
• arch - cpu architecture in use according to Go
• goVersion - version of Go runtime in use
• linking - type of rclone executable (static or dynamic)
• goTags - space separated build tags or "none"

debug/set-block-profile-rate: Set runtime.SetBlockProfileRate for blocking profiling.

SetBlockProfileRate controls the fraction of goroutine blocking events that are reported in the blocking profile. The profiler aims to sample an average of one blocking event per rate nanoseconds spent blocked.

To include every blocking event in the profile, pass rate = 1. To turn off profiling entirely, pass rate <= 0.

After calling this you can use this to see the blocking profile:

go tool pprof http://localhost:5572/debug/pprof/block

Parameters:

• rate - int

debug/set-gc-percent: Call runtime/debug.SetGCPercent for setting the garbage collection target percentage.

SetGCPercent sets the garbage collection target percentage: a collection is triggered when the ratio of freshly allocated data to live data remaining after the previous collection reaches this percentage. SetGCPercent returns the previous setting. The initial setting is the value of the GOGC environment variable at startup, or 100 if the variable is not set.

This setting may be effectively reduced in order to maintain a memory limit. A negative percentage effectively disables garbage collection, unless the memory limit is reached.

See https://pkg.go.dev/runtime/debug#SetMemoryLimit for more details.

Parameters:

• gc-percent - int

debug/set-mutex-profile-fraction: Set runtime.SetMutexProfileFraction for mutex profiling.

SetMutexProfileFraction controls the fraction of mutex contention events that are reported in the mutex profile. On average 1/rate events are reported. The previous rate is returned.

To turn off profiling entirely, pass rate 0. To just read the current rate, pass rate < 0. (For n>1 the details of sampling may change.)

Once this is set you can look use this to profile the mutex contention:

go tool pprof http://localhost:5572/debug/pprof/mutex

Parameters:

• rate - int

Results:

• previousRate - int

debug/set-soft-memory-limit: Call runtime/debug.SetMemoryLimit for setting a soft memory limit for the runtime.

SetMemoryLimit provides the runtime with a soft memory limit.

The runtime undertakes several processes to try to respect this memory limit, including adjustments to the frequency of garbage collections and returning memory to the underlying system more aggressively. This limit will be respected even if GOGC=off (or, if SetGCPercent(-1) is executed).

The input limit is provided as bytes, and includes all memory mapped, managed, and not released by the Go runtime. Notably, it does not account for space used by the Go binary and memory external to Go, such as memory managed by the underlying system on behalf of the process, or memory managed by non-Go code inside the same process. Examples of excluded memory sources include: OS kernel memory held on behalf of the process, memory allocated by C code, and memory mapped by syscall.Mmap (because it is not managed by the Go runtime).

A zero limit or a limit that's lower than the amount of memory used by the Go runtime may cause the garbage collector to run nearly continuously. However, the application may still make progress.

The memory limit is always respected by the Go runtime, so to effectively disable this behavior, set the limit very high. math.MaxInt64 is the canonical value for disabling the limit, but values much greater than the available memory on the underlying system work just as well.

See https://go.dev/doc/gc-guide for a detailed guide explaining the soft memory limit in more detail, as well as a variety of common use-cases and scenarios.

SetMemoryLimit returns the previously set memory limit. A negative input does not adjust the limit, and allows for retrieval of the currently set memory limit.

Parameters:

• mem-limit - int

fscache/clear: Clear the Fs cache.

This clears the fs cache. This is where remotes created from backends are cached for a short while to make repeated rc calls more efficient.

If you change the parameters of a backend then you may want to call this to clear an existing remote out of the cache before re-creating it.

Authentication is required for this call.

fscache/entries: Returns the number of entries in the fs cache.

This returns the number of entries in the fs cache.

Returns

• entries - number of items in the cache

Authentication is required for this call.

job/list: Lists the IDs of the running jobs

Parameters: None.

Results:

• jobids - array of integer job ids.

job/status: Reads the status of the job ID

Parameters:

• jobid - id of the job (integer).

Results:

• finished - boolean
• duration - time in seconds that the job ran for
• endTime - time the job finished (e.g. "2018-10-26T18:50:20.528746884+01:00")
• error - error from the job or empty string for no error
• finished - boolean whether the job has finished or not
• id - as passed in above
• startTime - time the job started (e.g. "2018-10-26T18:50:20.528336039+01:00")
• success - boolean - true for success false otherwise
• output - output of the job as would have been returned if called synchronously
• progress - output of the progress related to the underlying job

job/stop: Stop the running job

Parameters:

• jobid - id of the job (integer).

job/stopgroup: Stop all running jobs in a group

Parameters:

• group - name of the group (string).

mount/listmounts: Show current mount points

This shows currently mounted points, which can be used for performing an unmount.

This takes no parameters and returns

• mountPoints: list of current mount points

Eg

rclone rc mount/listmounts

Authentication is required for this call.

mount/mount: Create a new mount point

rclone allows Linux, FreeBSD, macOS and Windows to mount any of Rclone's cloud storage systems as a file system with FUSE.

If no mountType is provided, the priority is given as follows: 1. mount 2.cmount 3.mount2

This takes the following parameters:

• fs - a remote path to be mounted (required)
• mountPoint: valid path on the local machine (required)
• mountType: one of the values (mount, cmount, mount2) specifies the mount implementation to use
• mountOpt: a JSON object with Mount options in.
• vfsOpt: a JSON object with VFS options in.

Example:

rclone rc mount/mount fs=mydrive: mountPoint=/home/<user>/mountPoint
rclone rc mount/mount fs=mydrive: mountPoint=/home/<user>/mountPoint mountType=mount
rclone rc mount/mount fs=TestDrive: mountPoint=/mnt/tmp vfsOpt='{"CacheMode": 2}' mountOpt='{"AllowOther": true}'

The vfsOpt are as described in options/get and can be seen in the the "vfs" section when running and the mountOpt can be seen in the "mount" section:

rclone rc options/get

Authentication is required for this call.

mount/types: Show all possible mount types

This shows all possible mount types and returns them as a list.

This takes no parameters and returns

• mountTypes: list of mount types

The mount types are strings like "mount", "mount2", "cmount" and can be passed to mount/mount as the mountType parameter.

Eg

rclone rc mount/types

Authentication is required for this call.

mount/unmount: Unmount selected active mount

rclone allows Linux, FreeBSD, macOS and Windows to mount any of Rclone's cloud storage systems as a file system with FUSE.

This takes the following parameters:

• mountPoint: valid path on the local machine where the mount was created (required)

Example:

rclone rc mount/unmount mountPoint=/home/<user>/mountPoint

Authentication is required for this call.

mount/unmountall: Unmount all active mounts

rclone allows Linux, FreeBSD, macOS and Windows to mount any of Rclone's cloud storage systems as a file system with FUSE.

This takes no parameters and returns error if unmount does not succeed.

Eg

rclone rc mount/unmountall

Authentication is required for this call.

operations/about: Return the space used on the remote

This takes the following parameters:

• fs - a remote name string e.g. "drive:"

The result is as returned from rclone about --json

See the about command for more information on the above.

Authentication is required for this call.

operations/cleanup: Remove trashed files in the remote or path

This takes the following parameters:

• fs - a remote name string e.g. "drive:"

See the cleanup command for more information on the above.

Authentication is required for this call.

operations/copyfile: Copy a file from source remote to destination remote

This takes the following parameters:

• srcFs - a remote name string e.g. "drive:" for the source
• srcRemote - a path within that remote e.g. "file.txt" for the source
• dstFs - a remote name string e.g. "drive2:" for the destination
• dstRemote - a path within that remote e.g. "file2.txt" for the destination

Authentication is required for this call.

operations/copyurl: Copy the URL to the object

This takes the following parameters:

• fs - a remote name string e.g. "drive:"
• remote - a path within that remote e.g. "dir"
• url - string, URL to read from
• autoFilename - boolean, set to true to retrieve destination file name from url

See the copyurl command for more information on the above.

Authentication is required for this call.

operations/delete: Remove files in the path

This takes the following parameters:

• fs - a remote name string e.g. "drive:"

See the delete command for more information on the above.

Authentication is required for this call.

operations/deletefile: Remove the single file pointed to

This takes the following parameters:

• fs - a remote name string e.g. "drive:"
• remote - a path within that remote e.g. "dir"

See the deletefile command for more information on the above.

Authentication is required for this call.

operations/fsinfo: Return information about the remote

This takes the following parameters:

• fs - a remote name string e.g. "drive:"

This returns info about the remote passed in;

{
        // optional features and whether they are available or not
        "Features": {
                "About": true,
                "BucketBased": false,
                "BucketBasedRootOK": false,
                "CanHaveEmptyDirectories": true,
                "CaseInsensitive": false,
                "ChangeNotify": false,
                "CleanUp": false,
                "Command": true,
                "Copy": false,
                "DirCacheFlush": false,
                "DirMove": true,
                "Disconnect": false,
                "DuplicateFiles": false,
                "GetTier": false,
                "IsLocal": true,
                "ListR": false,
                "MergeDirs": false,
                "MetadataInfo": true,
                "Move": true,
                "OpenWriterAt": true,
                "PublicLink": false,
                "Purge": true,
                "PutStream": true,
                "PutUnchecked": false,
                "ReadMetadata": true,
                "ReadMimeType": false,
                "ServerSideAcrossConfigs": false,
                "SetTier": false,
                "SetWrapper": false,
                "Shutdown": false,
                "SlowHash": true,
                "SlowModTime": false,
                "UnWrap": false,
                "UserInfo": false,
                "UserMetadata": true,
                "WrapFs": false,
                "WriteMetadata": true,
                "WriteMimeType": false
        },
        // Names of hashes available
        "Hashes": [
                "md5",
                "sha1",
                "whirlpool",
                "crc32",
                "sha256",
                "dropbox",
                "mailru",
                "quickxor"
        ],
        "Name": "local",        // Name as created
        "Precision": 1,         // Precision of timestamps in ns
        "Root": "/",            // Path as created
        "String": "Local file system at /", // how the remote will appear in logs
        // Information about the system metadata for this backend
        "MetadataInfo": {
                "System": {
                        "atime": {
                                "Help": "Time of last access",
                                "Type": "RFC 3339",
                                "Example": "2006-01-02T15:04:05.999999999Z07:00"
                        },
                        "btime": {
                                "Help": "Time of file birth (creation)",
                                "Type": "RFC 3339",
                                "Example": "2006-01-02T15:04:05.999999999Z07:00"
                        },
                        "gid": {
                                "Help": "Group ID of owner",
                                "Type": "decimal number",
                                "Example": "500"
                        },
                        "mode": {
                                "Help": "File type and mode",
                                "Type": "octal, unix style",
                                "Example": "0100664"
                        },
                        "mtime": {
                                "Help": "Time of last modification",
                                "Type": "RFC 3339",
                                "Example": "2006-01-02T15:04:05.999999999Z07:00"
                        },
                        "rdev": {
                                "Help": "Device ID (if special file)",
                                "Type": "hexadecimal",
                                "Example": "1abc"
                        },
                        "uid": {
                                "Help": "User ID of owner",
                                "Type": "decimal number",
                                "Example": "500"
                        }
                },
                "Help": "Textual help string\n"
        }
}

This command does not have a command line equivalent so use this instead:

rclone rc --loopback operations/fsinfo fs=remote:

operations/list: List the given remote and path in JSON format

This takes the following parameters:

• fs - a remote name string e.g. "drive:"
• remote - a path within that remote e.g. "dir"
• opt - a dictionary of options to control the listing (optional)
  • recurse - If set recurse directories
  • noModTime - If set return modification time
  • showEncrypted - If set show decrypted names
  • showOrigIDs - If set show the IDs for each item if known
  • showHash - If set return a dictionary of hashes
  • noMimeType - If set don't show mime types
  • dirsOnly - If set only show directories
  • filesOnly - If set only show files
  • metadata - If set return metadata of objects also
  • hashTypes - array of strings of hash types to show if showHash set

Returns:

• list
  • This is an array of objects as described in the lsjson command

See the lsjson command for more information on the above and examples.

Authentication is required for this call.

operations/mkdir: Make a destination directory or container

This takes the following parameters:

• fs - a remote name string e.g. "drive:"
• remote - a path within that remote e.g. "dir"

See the mkdir command for more information on the above.

Authentication is required for this call.

operations/movefile: Move a file from source remote to destination remote

This takes the following parameters:

• srcFs - a remote name string e.g. "drive:" for the source
• srcRemote - a path within that remote e.g. "file.txt" for the source
• dstFs - a remote name string e.g. "drive2:" for the destination
• dstRemote - a path within that remote e.g. "file2.txt" for the destination

Authentication is required for this call.

operations/publiclink: Create or retrieve a public link to the given file or folder.

This takes the following parameters:

• fs - a remote name string e.g. "drive:"
• remote - a path within that remote e.g. "dir"
• unlink - boolean - if set removes the link rather than adding it (optional)
• expire - string - the expiry time of the link e.g. "1d" (optional)

Returns:

• url - URL of the resource

See the link command for more information on the above.

Authentication is required for this call.

operations/purge: Remove a directory or container and all of its contents

This takes the following parameters:

• fs - a remote name string e.g. "drive:"
• remote - a path within that remote e.g. "dir"

See the purge command for more information on the above.

Authentication is required for this call.

operations/rmdir: Remove an empty directory or container

This takes the following parameters:

• fs - a remote name string e.g. "drive:"
• remote - a path within that remote e.g. "dir"

See the rmdir command for more information on the above.

Authentication is required for this call.

operations/rmdirs: Remove all the empty directories in the path

This takes the following parameters:

• fs - a remote name string e.g. "drive:"
• remote - a path within that remote e.g. "dir"
• leaveRoot - boolean, set to true not to delete the root

See the rmdirs command for more information on the above.

Authentication is required for this call.

operations/size: Count the number of bytes and files in remote

This takes the following parameters:

• fs - a remote name string e.g. "drive:path/to/dir"

Returns:

• count - number of files
• bytes - number of bytes in those files

See the size command for more information on the above.

Authentication is required for this call.

operations/stat: Give information about the supplied file or directory

This takes the following parameters

• fs - a remote name string eg "drive:"
• remote - a path within that remote eg "dir"
• opt - a dictionary of options to control the listing (optional)
  • see operations/list for the options

The result is

• item - an object as described in the lsjson command. Will be null if not found.

Note that if you are only interested in files then it is much more efficient to set the filesOnly flag in the options.

See the lsjson command for more information on the above and examples.

Authentication is required for this call.

operations/uploadfile: Upload file using multiform/form-data

This takes the following parameters:

• fs - a remote name string e.g. "drive:"
• remote - a path within that remote e.g. "dir"
• each part in body represents a file to be uploaded

See the uploadfile command for more information on the above.

Authentication is required for this call.

options/blocks: List all the option blocks

Returns:

• options - a list of the options block names

options/get: Get all the global options

Returns an object where keys are option block names and values are an object with the current option values in.

Note that these are the global options which are unaffected by use of the _config and _filter parameters. If you wish to read the parameters set in _config then use options/config and for _filter use options/filter.

This shows the internal names of the option within rclone which should map to the external options very easily with a few exceptions.

options/local: Get the currently active config for this call

Returns an object with the keys "config" and "filter". The "config" key contains the local config and the "filter" key contains the local filters.

Note that these are the local options specific to this rc call. If _config was not supplied then they will be the global options. Likewise with "_filter".

This call is mostly useful for seeing if _config and _filter passing is working.

This shows the internal names of the option within rclone which should map to the external options very easily with a few exceptions.

options/set: Set an option

Parameters:

• option block name containing an object with
  • key: value

Repeated as often as required.

Only supply the options you wish to change. If an option is unknown it will be silently ignored. Not all options will have an effect when changed like this.

For example:

This sets DEBUG level logs (-vv) (these can be set by number or string)

rclone rc options/set --json '{"main": {"LogLevel": "DEBUG"}}'
rclone rc options/set --json '{"main": {"LogLevel": 8}}'

And this sets INFO level logs (-v)

rclone rc options/set --json '{"main": {"LogLevel": "INFO"}}'

And this sets NOTICE level logs (normal without -v)

rclone rc options/set --json '{"main": {"LogLevel": "NOTICE"}}'

pluginsctl/addPlugin: Add a plugin using url

Used for adding a plugin to the webgui.

This takes the following parameters:

• url - http url of the github repo where the plugin is hosted (http://github.com/rclone/rclone-webui-react).

Example:

rclone rc pluginsctl/addPlugin

Authentication is required for this call.

pluginsctl/getPluginsForType: Get plugins with type criteria

This shows all possible plugins by a mime type.

This takes the following parameters:

• type - supported mime type by a loaded plugin e.g. (video/mp4, audio/mp3).
• pluginType - filter plugins based on their type e.g. (DASHBOARD, FILE_HANDLER, TERMINAL).

Returns:

• loadedPlugins - list of current production plugins.
• testPlugins - list of temporarily loaded development plugins, usually running on a different server.

Example:

rclone rc pluginsctl/getPluginsForType type=video/mp4

Authentication is required for this call.

pluginsctl/listPlugins: Get the list of currently loaded plugins

This allows you to get the currently enabled plugins and their details.

This takes no parameters and returns:

• loadedPlugins - list of current production plugins.
• testPlugins - list of temporarily loaded development plugins, usually running on a different server.

E.g.

rclone rc pluginsctl/listPlugins

Authentication is required for this call.

pluginsctl/listTestPlugins: Show currently loaded test plugins

Allows listing of test plugins with the rclone.test set to true in package.json of the plugin.

This takes no parameters and returns:

• loadedTestPlugins - list of currently available test plugins.

E.g.

rclone rc pluginsctl/listTestPlugins

Authentication is required for this call.

pluginsctl/removePlugin: Remove a loaded plugin

This allows you to remove a plugin using it's name.

This takes parameters:

• name - name of the plugin in the format author/plugin_name.

E.g.

rclone rc pluginsctl/removePlugin name=rclone/video-plugin

Authentication is required for this call.

pluginsctl/removeTestPlugin: Remove a test plugin

This allows you to remove a plugin using it's name.

This takes the following parameters:

• name - name of the plugin in the format author/plugin_name.

Example:

rclone rc pluginsctl/removeTestPlugin name=rclone/rclone-webui-react

Authentication is required for this call.

rc/error: This returns an error

This returns an error with the input as part of its error string. Useful for testing error handling.

rc/list: List all the registered remote control commands

This lists all the registered remote control commands as a JSON map in the commands response.

rc/noop: Echo the input to the output parameters

This echoes the input parameters to the output parameters for testing purposes. It can be used to check that rclone is still alive and to check that parameter passing is working properly.

rc/noopauth: Echo the input to the output parameters requiring auth

This echoes the input parameters to the output parameters for testing purposes. It can be used to check that rclone is still alive and to check that parameter passing is working properly.

Authentication is required for this call.

sync/bisync: Perform bidirectional synchronization between two paths.

This takes the following parameters

• path1 - a remote directory string e.g. drive:path1
• path2 - a remote directory string e.g. drive:path2
• dryRun - dry-run mode
• resync - performs the resync run
• checkAccess - abort if RCLONE_TEST files are not found on both filesystems
• checkFilename - file name for checkAccess (default: RCLONE_TEST)
• maxDelete - abort sync if percentage of deleted files is above this threshold (default: 50)
• force - maxDelete safety check and run the sync
• checkSync - true by default, false disables comparison of final listings, only will skip sync, only compare listings from the last run
• removeEmptyDirs - remove empty directories at the final cleanup step
• filtersFile - read filtering patterns from a file
• workdir - server directory for history files (default: /home/ncw/.cache/rclone/bisync)
• noCleanup - retain working files

See bisync command help and full bisync description for more information.

Authentication is required for this call.

sync/copy: copy a directory from source remote to destination remote

This takes the following parameters:

• srcFs - a remote name string e.g. "drive:src" for the source
• dstFs - a remote name string e.g. "drive:dst" for the destination
• createEmptySrcDirs - create empty src directories on destination if set

See the copy command for more information on the above.

Authentication is required for this call.

sync/move: move a directory from source remote to destination remote

This takes the following parameters:

• srcFs - a remote name string e.g. "drive:src" for the source
• dstFs - a remote name string e.g. "drive:dst" for the destination
• createEmptySrcDirs - create empty src directories on destination if set
• deleteEmptySrcDirs - delete empty src directories if set

See the move command for more information on the above.

Authentication is required for this call.

sync/sync: sync a directory from source remote to destination remote

This takes the following parameters:

• srcFs - a remote name string e.g. "drive:src" for the source
• dstFs - a remote name string e.g. "drive:dst" for the destination
• createEmptySrcDirs - create empty src directories on destination if set

See the sync command for more information on the above.

Authentication is required for this call.

vfs/forget: Forget files or directories in the directory cache.

This forgets the paths in the directory cache causing them to be re-read from the remote when needed.

If no paths are passed in then it will forget all the paths in the directory cache.

rclone rc vfs/forget

Otherwise pass files or dirs in as file=path or dir=path. Any parameter key starting with file will forget that file and any starting with dir will forget that dir, e.g.

rclone rc vfs/forget file=hello file2=goodbye dir=home/junk

This command takes an "fs" parameter. If this parameter is not supplied and if there is only one VFS in use then that VFS will be used. If there is more than one VFS in use then the "fs" parameter must be supplied.

vfs/list: List active VFSes.

This lists the active VFSes.

It returns a list under the key "vfses" where the values are the VFS names that could be passed to the other VFS commands in the "fs" parameter.

vfs/poll-interval: Get the status or update the value of the poll-interval option.

Without any parameter given this returns the current status of the poll-interval setting.

When the interval=duration parameter is set, the poll-interval value is updated and the polling function is notified. Setting interval=0 disables poll-interval.

rclone rc vfs/poll-interval interval=5m

The timeout=duration parameter can be used to specify a time to wait for the current poll function to apply the new value. If timeout is less or equal 0, which is the default, wait indefinitely.

The new poll-interval value will only be active when the timeout is not reached.

If poll-interval is updated or disabled temporarily, some changes might not get picked up by the polling function, depending on the used remote.

This command takes an "fs" parameter. If this parameter is not supplied and if there is only one VFS in use then that VFS will be used. If there is more than one VFS in use then the "fs" parameter must be supplied.

vfs/refresh: Refresh the directory cache.

This reads the directories for the specified paths and freshens the directory cache.

If no paths are passed in then it will refresh the root directory.

rclone rc vfs/refresh

Otherwise pass directories in as dir=path. Any parameter key starting with dir will refresh that directory, e.g.

rclone rc vfs/refresh dir=home/junk dir2=data/misc

If the parameter recursive=true is given the whole directory tree will get refreshed. This refresh will use --fast-list if enabled.

This command takes an "fs" parameter. If this parameter is not supplied and if there is only one VFS in use then that VFS will be used. If there is more than one VFS in use then the "fs" parameter must be supplied.

vfs/stats: Stats for a VFS.

This returns stats for the selected VFS.

{
    // Status of the disk cache - only present if --vfs-cache-mode > off
    "diskCache": {
        "bytesUsed": 0,
        "erroredFiles": 0,
        "files": 0,
        "hashType": 1,
        "outOfSpace": false,
        "path": "/home/user/.cache/rclone/vfs/local/mnt/a",
        "pathMeta": "/home/user/.cache/rclone/vfsMeta/local/mnt/a",
        "uploadsInProgress": 0,
        "uploadsQueued": 0
    },
    "fs": "/mnt/a",
    "inUse": 1,
    // Status of the in memory metadata cache
    "metadataCache": {
        "dirs": 1,
        "files": 0
    },
    // Options as returned by options/get
    "opt": {
        "CacheMaxAge": 3600000000000,
        // ...
        "WriteWait": 1000000000
    }
}

This command takes an "fs" parameter. If this parameter is not supplied and if there is only one VFS in use then that VFS will be used. If there is more than one VFS in use then the "fs" parameter must be supplied.

{{< rem autogenerated stop >}}

Accessing the remote control via HTTP

Rclone implements a simple HTTP based protocol.

Each endpoint takes an JSON object and returns a JSON object or an error. The JSON objects are essentially a map of string names to values.

All calls must made using POST.

The input objects can be supplied using URL parameters, POST parameters or by supplying "Content-Type: application/json" and a JSON blob in the body. There are examples of these below using curl.

The response will be a JSON blob in the body of the response. This is formatted to be reasonably human-readable.

Error returns

If an error occurs then there will be an HTTP error status (e.g. 500) and the body of the response will contain a JSON encoded error object, e.g.

{
    "error": "Expecting string value for key \"remote\" (was float64)",
    "input": {
        "fs": "/tmp",
        "remote": 3
    },
    "status": 400
    "path": "operations/rmdir",
}

The keys in the error response are

• error - error string
• input - the input parameters to the call
• status - the HTTP status code
• path - the path of the call

CORS

The sever implements basic CORS support and allows all origins for that. The response to a preflight OPTIONS request will echo the requested "Access-Control-Request-Headers" back.

Using POST with URL parameters only

curl -X POST 'http://localhost:5572/rc/noop?potato=1&sausage=2'

Response

{
	"potato": "1",
	"sausage": "2"
}

Here is what an error response looks like:

curl -X POST 'http://localhost:5572/rc/error?potato=1&sausage=2'

{
	"error": "arbitrary error on input map[potato:1 sausage:2]",
	"input": {
		"potato": "1",
		"sausage": "2"
	}
}

Note that curl doesn't return errors to the shell unless you use the -f option

$ curl -f -X POST 'http://localhost:5572/rc/error?potato=1&sausage=2'
curl: (22) The requested URL returned error: 400 Bad Request
$ echo $?
22

Using POST with a form

curl --data "potato=1" --data "sausage=2" http://localhost:5572/rc/noop

Response

{
	"potato": "1",
	"sausage": "2"
}

Note that you can combine these with URL parameters too with the POST parameters taking precedence.

curl --data "potato=1" --data "sausage=2" "http://localhost:5572/rc/noop?rutabaga=3&sausage=4"

Response

{
	"potato": "1",
	"rutabaga": "3",
	"sausage": "4"
}

Using POST with a JSON blob

curl -H "Content-Type: application/json" -X POST -d '{"potato":2,"sausage":1}' http://localhost:5572/rc/noop

response

{
	"password": "xyz",
	"username": "xyz"
}

This can be combined with URL parameters too if required. The JSON blob takes precedence.

curl -H "Content-Type: application/json" -X POST -d '{"potato":2,"sausage":1}' 'http://localhost:5572/rc/noop?rutabaga=3&potato=4'

{
	"potato": 2,
	"rutabaga": "3",
	"sausage": 1
}

Debugging rclone with pprof

If you use the --rc flag this will also enable the use of the go profiling tools on the same port.

To use these, first install go.

Debugging memory use

To profile rclone's memory use you can run:

go tool pprof -web http://localhost:5572/debug/pprof/heap

This should open a page in your browser showing what is using what memory.

You can also use the -text flag to produce a textual summary

$ go tool pprof -text http://localhost:5572/debug/pprof/heap
Showing nodes accounting for 1537.03kB, 100% of 1537.03kB total
      flat  flat%   sum%        cum   cum%
 1024.03kB 66.62% 66.62%  1024.03kB 66.62%  github.com/rclone/rclone/vendor/golang.org/x/net/http2/hpack.addDecoderNode
     513kB 33.38%   100%      513kB 33.38%  net/http.newBufioWriterSize
         0     0%   100%  1024.03kB 66.62%  github.com/rclone/rclone/cmd/all.init
         0     0%   100%  1024.03kB 66.62%  github.com/rclone/rclone/cmd/serve.init
         0     0%   100%  1024.03kB 66.62%  github.com/rclone/rclone/cmd/serve/restic.init
         0     0%   100%  1024.03kB 66.62%  github.com/rclone/rclone/vendor/golang.org/x/net/http2.init
         0     0%   100%  1024.03kB 66.62%  github.com/rclone/rclone/vendor/golang.org/x/net/http2/hpack.init
         0     0%   100%  1024.03kB 66.62%  github.com/rclone/rclone/vendor/golang.org/x/net/http2/hpack.init.0
         0     0%   100%  1024.03kB 66.62%  main.init
         0     0%   100%      513kB 33.38%  net/http.(*conn).readRequest
         0     0%   100%      513kB 33.38%  net/http.(*conn).serve
         0     0%   100%  1024.03kB 66.62%  runtime.main

Debugging go routine leaks

Memory leaks are most often caused by go routine leaks keeping memory alive which should have been garbage collected.

See all active go routines using

curl http://localhost:5572/debug/pprof/goroutine?debug=1

Or go to http://localhost:5572/debug/pprof/goroutine?debug=1 in your browser.

Other profiles to look at

You can see a summary of profiles available at http://localhost:5572/debug/pprof/

Here is how to use some of them:

• Memory: go tool pprof http://localhost:5572/debug/pprof/heap
• Go routines: curl http://localhost:5572/debug/pprof/goroutine?debug=1
• 30-second CPU profile: go tool pprof http://localhost:5572/debug/pprof/profile
• 5-second execution trace: wget http://localhost:5572/debug/pprof/trace?seconds=5
• Goroutine blocking profile
  • Enable first with: rclone rc debug/set-block-profile-rate rate=1 (docs)
  • go tool pprof http://localhost:5572/debug/pprof/block
• Contended mutexes:
  • Enable first with: rclone rc debug/set-mutex-profile-fraction rate=1 (docs)
  • go tool pprof http://localhost:5572/debug/pprof/mutex

See the net/http/pprof docs for more info on how to use the profiling and for a general overview see the Go team's blog post on profiling go programs.

The profiling hook is zero overhead unless it is used.