syncthing/man/syncthing.1

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.TH "SYNCTHING" "1" "Apr 04, 2025" "v1.29.3" "Syncthing"
.SH NAME
syncthing \- Syncthing
.SH SYNOPSIS
.INDENT 0.0
.INDENT 3.5
.sp
.EX
syncthing [serve]
          [\-\-audit] [\-\-auditfile=<file|\-|\-\->] [\-\-browser\-only] [\-\-device\-id]
          [\-\-generate=<dir>] [\-\-gui\-address=<address>] [\-\-gui\-apikey=<key>]
          [\-\-home=<dir> | \-\-config=<dir> \-\-data=<dir>]
          [\-\-logfile=<filename>] [\-\-logflags=<flags>]
          [\-\-log\-max\-old\-files=<num>] [\-\-log\-max\-size=<num>]
          [\-\-no\-browser] [\-\-no\-console] [\-\-no\-restart] [\-\-paths] [\-\-paused]
          [\-\-no\-default\-folder] [\-\-skip\-port\-probing]
          [\-\-reset\-database] [\-\-reset\-deltas] [\-\-unpaused] [\-\-allow\-newer\-config]
          [\-\-upgrade] [\-\-no\-upgrade] [\-\-upgrade\-check] [\-\-upgrade\-to=<url>]
          [\-\-verbose] [\-\-version] [\-\-help] [\-\-debug\-*]

syncthing generate
          [\-\-home=<dir> | \-\-config=<dir>]
          [\-\-gui\-user=<username>] [\-\-gui\-password=<password|\->]
          [\-\-no\-default\-folder] [\-\-skip\-port\-probing] [\-\-no\-console]
          [\-\-help]

syncthing decrypt (\-\-to=<dir> | \-\-verify\-only)
          [\-\-password=<pw>] [\-\-folder\-id=<id>] [\-\-token\-path=<file>]
          [\-\-continue] [\-\-verbose] [\-\-version] [\-\-help]
          <path>

syncthing cli
          [\-\-home=<dir> | \-\-config=<dir> \-\-data=<dir>]
          [\-\-gui\-address=<address>] [\-\-gui\-apikey=<key>]
          [\-\-help]
          <command> [command options...] [arguments...]
.EE
.UNINDENT
.UNINDENT
.SH DESCRIPTION
.sp
Syncthing lets you synchronize your files bidirectionally across multiple
devices. This means the creation, modification or deletion of files on one
machine will automatically be replicated to your other devices. We believe your
data is your data alone and you deserve to choose where it is stored. Therefore
Syncthing does not upload your data to the cloud but exchanges your data across
your machines as soon as they are online at the same time.
.sp
The \fBsyncthing\fP core application is a command\-line program which usually runs
in the background and handles the synchronization. It provides a built\-in, HTML
and JavaScript based user interface to be controlled from a web browser. This
frontend communicates with the core application through some HTTP APIs, which
other apps like graphical system integration helpers can use as well, for
greatest flexibility. A link to reach the GUI and API is printed among the first
few log messages.
.SH OPTIONS
.INDENT 0.0
.TP
.B \-\-allow\-newer\-config
Try loading a config file written by a newer program version, instead of
failing immediately.
.UNINDENT
.INDENT 0.0
.TP
.B \-\-audit
Write events to timestamped file \fBaudit\-YYYYMMDD\-HHMMSS.log\fP\&.
.UNINDENT
.INDENT 0.0
.TP
.B \-\-auditfile=<file|\-|\-\->
Use specified file or stream (\fB\(dq\-\(dq\fP for stdout, \fB\(dq\-\-\(dq\fP for stderr) for
audit events, rather than the timestamped default file name.
.UNINDENT
.INDENT 0.0
.TP
.B \-\-browser\-only
Open the web UI in a browser for an already running Syncthing instance.
.UNINDENT
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.TP
.B \-\-device\-id
Print device ID to command line.
.UNINDENT
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.TP
.B \-\-generate=<dir>
Generate key and config in specified dir, then exit.
.UNINDENT
.INDENT 0.0
.TP
.B \-\-gui\-address=<address>
Override GUI listen address. Set this to an address (\fB0.0.0.0:8384\fP)
or a URL (\fBhttp://0.0.0.0:8384\fP). Supported schemes are \fBhttp\fP for
plain HTTP, \fBhttps\fP for HTTP over TLS, \fBunix\fP for plain Unix sockets
or \fBunixs\fP for TLS over Unix sockets. A Unix socket could look like this:
\fBunix:///run/syncthing/syncthing.socket\fP (notice the three slashes: two
as part of the URL structure, one to specify an absolute path).
.UNINDENT
.INDENT 0.0
.TP
.B \-\-gui\-apikey=<string>
Override the API key needed to access the GUI / REST API.
.UNINDENT
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.TP
.B \-\-gui\-password=<password|\->
Specify new GUI authentication password, to update the config file.  Read
from the standard input stream if only a single dash (\fB\-\fP) is given.  A
plaintext password is hashed before writing to the config file, but an
already bcrypt\-hashed input is stored verbatim.  As a special case, giving
the existing password hash as password will leave it untouched.
.UNINDENT
.INDENT 0.0
.TP
.B \-\-gui\-user=<username>
Specify new GUI authentication user name, to update the config file.
.UNINDENT
.INDENT 0.0
.TP
.B \-\-help, \-h
Show help text about command line usage.  Context\-sensitive depending on the
given subcommand.
.UNINDENT
.INDENT 0.0
.TP
.B \-\-home=<dir>
Set common configuration and data directory. The default configuration
directory is \fB$XDG_STATE_HOME/syncthing\fP or
\fB$HOME/.local/state/syncthing\fP (Unix\-like),
\fB$HOME/Library/Application Support/Syncthing\fP (Mac) and
\fB%LOCALAPPDATA%\eSyncthing\fP (Windows).
.UNINDENT
.INDENT 0.0
.TP
.B \-\-config=<dir>
Set configuration directory. Alternative to \fB\-\-home\fP and must be used
together with \fB\-\-data\fP\&.
.UNINDENT
.INDENT 0.0
.TP
.B \-\-data=<dir>
Set data (e.g. database) directory. Alternative to \fB\-\-home\fP and must be used
together with \fB\-\-config\fP\&.
.UNINDENT
.INDENT 0.0
.TP
.B \-\-logfile=<filename>
Set destination filename for logging (use \fB\(dq\-\(dq\fP for stdout, which is the
default option).
.UNINDENT
.INDENT 0.0
.TP
.B \-\-logflags=<flags>
Select information in log line prefix. The \fB\-\-logflags\fP value is a sum of
the following:
.INDENT 7.0
.IP \(bu 2
1: Date
.IP \(bu 2
2: Time
.IP \(bu 2
4: Microsecond time
.IP \(bu 2
8: Long filename
.IP \(bu 2
16: Short filename
.UNINDENT
.sp
To prefix each log line with date and time, set \fB\-\-logflags=3\fP (1 + 2 from
above). The value 0 is used to disable all of the above. The default is to
show time only (2).
.UNINDENT
.INDENT 0.0
.TP
.B \-\-log\-max\-old\-files=<num>
Number of old files to keep (zero to keep only current).  Applies only when
log rotation is enabled through \fB\-\-log\-max\-size\fP\&.
.UNINDENT
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.TP
.B \-\-log\-max\-size=<num>
Maximum size of any log file (zero to disable log rotation).
.UNINDENT
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.TP
.B \-\-no\-browser
Do not start a browser.
.UNINDENT
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.TP
.B \-\-no\-console
Hide the console window. (On Windows only)
.UNINDENT
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.TP
.B \-\-no\-default\-folder
Don’t create a default folder when generating an initial configuration /
starting for the first time.
.UNINDENT
.INDENT 0.0
.TP
.B \-\-no\-restart
Do not restart Syncthing when it exits. The monitor process will still run
to handle crashes and writing to logfiles (if configured to).
.UNINDENT
.INDENT 0.0
.TP
.B \-\-no\-upgrade
Disable automatic upgrades.  Equivalent to the \fBSTNOUPGRADE\fP environment
variable, see below.
.UNINDENT
.INDENT 0.0
.TP
.B \-\-paths
Print the paths used for configuration, keys, database, GUI overrides,
default sync folder and the log file.
.UNINDENT
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.TP
.B \-\-paused
Start with all devices and folders paused.
.UNINDENT
.INDENT 0.0
.TP
.B \-\-reset\-database
Reset the database, forcing a full rescan and resync. Create \fI\&.stfolder\fP
folders in each sync folder if they do not already exist. \fBCaution\fP:
Ensure that all sync folders which are mountpoints are already mounted.
Inconsistent versions may result if the mountpoint is later mounted and
contains older versions.
.UNINDENT
.INDENT 0.0
.TP
.B \-\-reset\-deltas
Reset delta index IDs, forcing a full index exchange.
.UNINDENT
.INDENT 0.0
.TP
.B \-\-skip\-port\-probing
Don’t try to find unused random ports for the GUI and listen address when
generating an initial configuration / starting for the first time.
.UNINDENT
.INDENT 0.0
.TP
.B \-\-unpaused
Start with all devices and folders unpaused.
.UNINDENT
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.TP
.B \-\-upgrade
Perform upgrade.
.UNINDENT
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.TP
.B \-\-upgrade\-check
Check for available upgrade.
.UNINDENT
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.TP
.B \-\-upgrade\-to=<url>
Force upgrade directly from specified URL.
.UNINDENT
.INDENT 0.0
.TP
.B \-\-verbose
Print verbose log output.
.UNINDENT
.INDENT 0.0
.TP
.B \-\-version
Show version.
.UNINDENT
.INDENT 0.0
.TP
.B \-\-to=<dir>
Destination directory where files should be stored after decryption.
.UNINDENT
.INDENT 0.0
.TP
.B \-\-verify\-only
Don’t write decrypted files to disk (but verify plaintext hashes).
.UNINDENT
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.TP
.B \-\-password=<pw>
Folder password for decryption / verification.  Can be passed through the
\fBFOLDER_PASSWORD\fP environment variable instead to avoid recording in a
shell’s history buffer or sniffing from the running processes list.
.UNINDENT
.INDENT 0.0
.TP
.B \-\-folder\-id=<id>
Folder ID of the encrypted folder, if it cannot be determined automatically.
.UNINDENT
.INDENT 0.0
.TP
.B \-\-token\-path=<file>
Path to the token file within the folder (used to determine folder ID).
.UNINDENT
.INDENT 0.0
.TP
.B \-\-continue
Continue processing next file in case of error, instead of aborting.
.UNINDENT
.SH EXIT CODES
.INDENT 0.0
.TP
.B 0
Success / Shutdown
.TP
.B 1
Error
.TP
.B 2
Upgrade not available
.TP
.B 3
Restarting
.TP
.B 4
Upgrading
.UNINDENT
.sp
Exit codes over 125 are usually returned by the shell/binary loader/default
signal handler. Exit codes over 128+N on Unix usually represent the signal which
caused the process to exit. For example, \fB128 + 9 (SIGKILL) = 137\fP\&.
.SH SUBCOMMANDS
.sp
The command line syntax actually supports different modes of operation through
several subcommands, specified as the first argument.  If omitted, the default
\fBserve\fP is assumed.
.sp
The initial setup of a device ID and default configuration can be called
explicitly with the \fBgenerate\fP subcommand.  It can also update the configured
GUI authentication credentials, without going through the REST API.  An existing
device certificate is left untouched.  If the configuration file already exists,
it is validated and updated to the latest configuration schema, including adding
default values for any new options.
.sp
The \fBdecrypt\fP subcommand is used in conjunction with untrusted (encrypted)
devices, see the relevant section on \fI\%decryption\fP for
details.  It does not depend on Syncthing to be running, but works on offline
data.
.sp
To work with the REST API for debugging or automating things in Syncthing, the
\fBcli\fP subcommand provides easy access to individual features.  It basically
saves the hassle of handling HTTP connections and API authentication.
.sp
The available subcommands are grouped into several nested hierarchies and some
parts dynamically generated from the running Syncthing instance.  On every
level, the \fB\-\-help\fP option lists the available properties, actions and
commands for the user to discover interactively.  The top\-level groups are:
.INDENT 0.0
.TP
.B config
Access the live configuration in a running instance over the REST API to
retrieve (get) or update (set) values in a fine\-grained way.  The hierarchy
is based on the same structure as used in the JSON / XML representations.
.TP
.B show
Show system properties and status of a running instance.  The output is
passed on directly from the REST API response and therefore requires parsing
JSON format.
.TP
.B operations
Control the overall program operation such as restarting or handling
upgrades, as well as triggering some actions on a per\-folder basis.  Can
also configure the default ignore patterns from a plain text ignore file.
.TP
.B errors
Examine pending error conditions that need attention from the user, or
acknowledge (clear) them.
.TP
.B debug
Various tools to aid in diagnosing problems or collection information for
bug reports.  Some of these commands access the database directly and can
therefore only work when Syncthing is not running.
.TP
.B \fB\-\fP (a single dash)
Reads subsequent commands from the standard input stream, without needing to
call the \fBsyncthing cli\fP command over and over.  Exits on any invalid
command or when EOF (end\-of\-file) is received.
.UNINDENT
.SH PROXIES
.sp
Syncthing can use a SOCKS, HTTP, or HTTPS proxy to talk to the outside
world. The proxy is used for outgoing connections only \- it is not possible
to accept incoming connections through the proxy. The proxy is configured
through the environment variable \fBall_proxy\fP\&. Somewhat unusually, this
variable must be named in lower case \- it is not “ALL_PROXY”. For
example:
.INDENT 0.0
.INDENT 3.5
.sp
.EX
$ export all_proxy=socks://192.0.2.42:8081
.EE
.UNINDENT
.UNINDENT
.SH DEVELOPMENT SETTINGS
.sp
The following environment variables modify Syncthing’s behavior in ways that
are mostly useful for developers. Use with care.
If you start Syncthing from within service managers like systemd or supervisor,
path expansion may not be supported.
.INDENT 0.0
.TP
.B STTRACE
Used to increase the debugging verbosity in specific or all facilities,
generally mapping to a Go package. Enabling any of these also enables
microsecond timestamps, file names plus line numbers. Enter a
comma\-separated string of facilities to trace. \fBsyncthing \-\-help\fP always
outputs an up\-to\-date list. The valid facility strings are:
.INDENT 7.0
.TP
.B Main and operational facilities:
.INDENT 7.0
.TP
.B config
Configuration loading and saving.
.TP
.B db
The database layer.
.TP
.B main
Main package.
.TP
.B model
The root hub; the largest chunk of the system. File pulling, index
transmission and requests for chunks.
.TP
.B scanner
File change detection and hashing.
.TP
.B versioner
File versioning.
.UNINDENT
.TP
.B Networking facilities:
.INDENT 7.0
.TP
.B beacon
Multicast and broadcast UDP discovery packets: Selected interfaces
and addresses.
.TP
.B connections
Connection handling.
.TP
.B dialer
Dialing connections.
.TP
.B discover
Remote device discovery requests, replies and registration of
devices.
.TP
.B nat
NAT discovery and port mapping.
.TP
.B pmp
NAT\-PMP discovery and port mapping.
.TP
.B protocol
The BEP protocol.
.TP
.B relay
Relay interaction (\fBstrelaysrv\fP).
.TP
.B upnp
UPnP discovery and port mapping.
.UNINDENT
.TP
.B Other facilities:
.INDENT 7.0
.TP
.B fs
Filesystem access.
.TP
.B events
Event generation and logging.
.TP
.B http
REST API.
.TP
.B sha256
SHA256 hashing package (this facility currently unused).
.TP
.B stats
Persistent device and folder statistics.
.TP
.B sync
Mutexes. Used for debugging race conditions and deadlocks.
.TP
.B upgrade
Binary upgrades.
.TP
.B walkfs
Filesystem access while walking.
.TP
.B all
All of the above.
.UNINDENT
.UNINDENT
.TP
.B STBLOCKPROFILE
Write block profiles to \fBblock\-$pid\-$timestamp.pprof\fP every 20 seconds.
.TP
.B STCPUPROFILE
Write a CPU profile to \fBcpu\-$pid.pprof\fP on exit.
.TP
.B STDEADLOCKTIMEOUT
Used for debugging internal deadlocks; sets debug sensitivity. Use only
under direction of a developer.
.TP
.B STLOCKTHRESHOLD
Used for debugging internal deadlocks; sets debug sensitivity. Use only
under direction of a developer.
.TP
.B STGUIADDRESS
Override GUI listen address.  Equivalent to passing \fI\%\-\-gui\-address\fP\&.
.TP
.B STGUIAPIKEY
Override the API key needed to access the GUI / REST API.  Equivalent to
passing \fI\%\-\-gui\-apikey\fP\&.
.TP
.B STGUIASSETS
Directory to load GUI assets from. Overrides compiled in assets. Useful for
developing webgui, commonly use \fBSTGUIASSETS=gui bin/syncthing\fP\&.
.TP
.B STHEAPPROFILE
Write heap profiles to \fBheap\-$pid\-$timestamp.pprof\fP each time heap usage
increases.
.TP
.B STNODEFAULTFOLDER
Don’t create a default folder when starting for the first time. This
variable will be ignored anytime after the first run.  Equivalent to the
\fI\%\-\-no\-default\-folder\fP flag.
.TP
.B STNORESTART
Equivalent to the \fI\%\-\-no\-restart\fP flag.
.TP
.B STNOUPGRADE
Disable automatic upgrades.  Equivalent to the \fI\%\-\-no\-upgrade\fP flag.
.TP
.B STPROFILER
Set to a listen address such as “127.0.0.1:9090” to start the profiler with
HTTP access, which then can be reached at
\X'tty: link http://localhost:9090/debug/pprof'\fI\%http://localhost:9090/debug/pprof\fP\X'tty: link'\&. See \fBgo tool pprof\fP for more
information.
.TP
.B STPERFSTATS
Write running performance statistics to \fBperf\-$pid.csv\fP\&. Not supported on
Windows.
.TP
.B STRECHECKDBEVERY
Time before folder statistics (file, dir, … counts) are recalculated from
scratch. The given duration must be parseable by Go’s \fBtime.ParseDuration\fP\&. If
missing or not parseable, the default value of 1 month is used. To force
recalculation on every startup, set it to \fB1s\fP\&.
.TP
.B STGCINDIRECTEVERY
Sets the time interval in between database garbage collection runs.  The
given duration must be parseable by Go’s \fBtime.ParseDuration\fP\&.
.TP
.B GOMAXPROCS
Set the maximum number of CPU cores to use. Defaults to all available CPU
cores.
.TP
.B GOGC
Percentage of heap growth at which to trigger GC. Default is 100. Lower
numbers keep peak memory usage down, at the price of CPU usage
(i.e. performance).
.TP
.B LOGGER_DISCARD
Hack to completely disable logging, for example when running benchmarks.
Set to any nonempty value to use it.
.UNINDENT
.SH SEE ALSO
.sp
\fBsyncthing\-config(5)\fP, \fBsyncthing\-stignore(5)\fP,
\fBsyncthing\-device\-ids(7)\fP, \fBsyncthing\-security(7)\fP,
\fBsyncthing\-networking(7)\fP, \fBsyncthing\-versioning(7)\fP,
\fBsyncthing\-faq(7)\fP
.SH AUTHOR
The Syncthing Authors
.SH COPYRIGHT
2014-2019, The Syncthing Authors
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