Provided by: syncthing_1.18.0~ds1-3ubuntu0.3_amd64 
NAME
syncthing - Syncthing
SYNOPSIS
syncthing [-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>]
[-no-browser] [-no-console] [-no-restart] [-paths] [-paused]
[-reset-database] [-reset-deltas] [-unpaused] [-upgrade]
[-upgrade-check] [-upgrade-to=<url>] [-verbose] [-version]
DESCRIPTION
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.
The syncthing 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.
OPTIONS
-audit Write events to timestamped file audit-YYYYMMDD-HHMMSS.log.
-auditfile=<file|-|-->
Use specified file or stream ("-" for stdout, "--" for stderr) for audit events, rather than the
timestamped default file name.
-browser-only
Open the web UI in a browser for an already running Syncthing instance.
-device-id
Print device ID to command line.
-generate=<dir>
Generate key and config in specified dir, then exit.
-gui-address=<address>
Override GUI listen address. Set this to an address (0.0.0.0:8384) or file path (/var/run/st.sock,
for UNIX sockets).
-home=<dir>
Set common configuration and data directory. The default configuration directory is
$HOME/.config/syncthing (Unix-like), $HOME/Library/Application Support/Syncthing (Mac) and
%LOCALAPPDATA%\Syncthing (Windows).
-config=<dir>
Set configuration directory. Alternative to -home and must be used together with -data.
-data=<dir>
Set data (e.g. database) directory. Alternative to -home and must be used together with -config.
-logfile=<filename>
Set destination filename for logging (use "-" for stdout, which is the default option).
-logflags=<flags>
Select information in log line prefix. The -logflags value is a sum of the following:
• 1: Date
• 2: Time
• 4: Microsecond time
• 8: Long filename
• 16: Short filename
To prefix each log line with date and time, set -logflags=3 (1 + 2 from above). The value 0 is
used to disable all of the above. The default is to show time only (2).
-no-browser
Do not start a browser.
-no-console
Hide the console window. (On Windows only)
-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).
-paths Print the paths used for configuration, keys, database, GUI overrides, default sync folder and the
log file.
-paused
Start with all devices and folders paused.
-reset-database
Reset the database, forcing a full rescan and resync. Create .stfolder folders in each sync folder
if they do not already exist. Caution: 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.
-reset-deltas
Reset delta index IDs, forcing a full index exchange.
-unpaused
Start with all devices and folders unpaused.
-upgrade
Perform upgrade.
-upgrade-check
Check for available upgrade.
-upgrade-to=<url>
Force upgrade directly from specified URL.
-verbose
Print verbose log output.
-version
Show version.
EXIT CODES
0 Success / Shutdown
1 Error
2 Upgrade not available
3 Restarting
4 Upgrading
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, 128 + 9
(SIGKILL) = 137.
PROXIES
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 all_proxy. Somewhat unusually, this variable must be
named in lower case - it is not “ALL_PROXY”. For example:
$ export all_proxy=socks://192.0.2.42:8081
DEVELOPMENT SETTINGS
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.
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. syncthing -help always outputs an
up-to-date list. The valid facility strings are:
Main and operational facilities:
config Configuration loading and saving.
db The database layer.
main Main package.
model The root hub; the largest chunk of the system. File pulling, index transmission and
requests for chunks.
scanner
File change detection and hashing.
versioner
File versioning.
Networking facilities:
beacon Multicast and broadcast UDP discovery packets: Selected interfaces and addresses.
connections
Connection handling.
dialer Dialing connections.
discover
Remote device discovery requests, replies and registration of devices.
nat NAT discovery and port mapping.
pmp NAT-PMP discovery and port mapping.
protocol
The BEP protocol.
relay Relay interaction (strelaysrv).
upnp UPnP discovery and port mapping.
Other facilities:
fs Filesystem access.
events Event generation and logging.
http REST API.
sha256 SHA256 hashing package (this facility currently unused).
stats Persistent device and folder statistics.
sync Mutexes. Used for debugging race conditions and deadlocks.
upgrade
Binary upgrades.
walkfs Filesystem access while walking.
all All of the above.
STBLOCKPROFILE
Write block profiles to block-$pid-$timestamp.pprof every 20 seconds.
STCPUPROFILE
Write a CPU profile to cpu-$pid.pprof on exit.
STDEADLOCKTIMEOUT
Used for debugging internal deadlocks; sets debug sensitivity. Use only under direction of a
developer.
STDEADLOCKTHRESHOLD
Used for debugging internal deadlocks; sets debug sensitivity. Use only under direction of a
developer.
STGUIASSETS
Directory to load GUI assets from. Overrides compiled in assets. Useful for developing webgui,
commonly use STGUIASSETS=gui bin/syncthing.
STHASHING
Specify which hashing package to use. Defaults to automatic based on performance. Specify “minio”
(compatibility) or “standard” for the default Go implementation.
STHEAPPROFILE
Write heap profiles to heap-$pid-$timestamp.pprof each time heap usage increases.
STNODEFAULTFOLDER
Don’t create a default folder when starting for the first time. This variable will be ignored
anytime after the first run.
STNORESTART
Equivalent to the -no-restart flag
STNOUPGRADE
Disable automatic upgrades.
STPROFILER
Set to a listen address such as “127.0.0.1:9090” to start the profiler with HTTP access, which
then can be reached at http://localhost:9090/debug/pprof. See go tool pprof for more information.
STPERFSTATS
Write running performance statistics to perf-$pid.csv. Not supported on Windows.
STRECHECKDBEVERY
Time before folder statistics (file, dir, … counts) are recalculated from scratch. The given
duration must be parseable by Go’s time.ParseDuration. If missing or not parseable, the default
value of 1 month is used. To force recalculation on every startup, set it to 1s.
GOMAXPROCS
Set the maximum number of CPU cores to use. Defaults to all available CPU cores.
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).
SEE ALSO
syncthing-config(5), syncthing-stignore(5), syncthing-device-ids(7), syncthing-security(7),
syncthing-networking(7), syncthing-versioning(7), syncthing-faq(7)
AUTHOR
The Syncthing Authors
COPYRIGHT
2014-2019, The Syncthing Authors
v1 Jun 14, 2021 SYNCTHING(1)