Valheim launch parameters: quick reference
Valheim's dedicated server has no settings file: every option is a launch parameter on the valheim_server line of start_server.sh (Linux) or start_headless_server.bat (Windows). Iron Gate's own start script for 1.0 reads ./valheim_server.x86_64 -name "My server" -port 2456 -world "Dedicated" -password "secret" -crossplay. Copy the script before you edit it, because a server update replaces the original. This page lists every parameter the 1.0.17 server reads, with its default; the configuration guide explains each one in depth.
Every parameter and its default
| Parameter | Default | What it does |
|---|---|---|
-name | the world name | Name shown in the server list |
-port | 2456 | Game port; the Steam backend also uses the port above it |
-world | Dedicated | World to load, or create if it does not exist |
-password | none | Join password: at least 5 characters, not inside the world name or seed, on a public server |
-public | 1 | 1 lists the server in the community list, 0 hides it; 1 also applies when you leave it out |
-crossplay | off | Uses the crossplay (PlayFab) backend so every platform can join; no port forwarding |
-savedir | ~/.config/unity3d/IronGate/Valheim | Where worlds and the admin, ban and permitted lists are kept |
-saveinterval | 1800 | Seconds between world saves |
-backups | 4 | Automatic backups kept: one after -backupshort, the rest -backuplong apart |
-backupshort / -backuplong | 7200 / 43200 | Seconds between the first and the later automatic backups |
-instanceid | none | A unique value per server when several share a port from one machine |
-preset | none | World modifier preset: normal, casual, easy, hard, hardcore, immersive or hammer |
-modifier | none | One world modifier and its value, for example -modifier raids none; put it after any -preset |
-setkey | none | A world key such as nomap, passivemobs, nobuildcost or playerevents |
-resetmodifiers | off | Clears the world's modifier keys before the options above are applied |
-simulationdistance | 2 | 0 to 6: caps every player's draw distance, and with it how much each one simulates |
-logfile | none | Writes the log to this file |
Two traps. A public server, which is the default, quits at start with Error bad password in its log if the password is too short or appears inside the world name or seed. And a -modifier value must be the option's name: a number is read as the option's position in the game's list, so -modifier resources 2 sets Less, not double.
Admins, bans and the whitelist
These are not launch parameters but three files in the save folder, one platform ID per line: adminlist.txt, bannedlist.txt and permittedlist.txt. See grant admin, ban, kick and unban and the whitelist. On a Supercraft server, set all three in the access settings of the configuration tab.
Frequently Asked Questions
Do I need to restart the server to change launch parameters?
Yes. Launch parameters are read once, when the server starts. The admin, ban and permitted lists are the exception: the server rereads those files within about 10 seconds.
Is a Valheim server public by default?
Yes. A server started without -public is listed, exactly as with -public 1, and it then needs a valid password.
Can I set the world seed with a launch parameter?
No. None of the server's options takes a seed; a world it creates gets a random one. Create the world with your seed in the game and upload it, or use a seed mod.
Can I run several Valheim servers on one machine?
Yes. Give each its own -port (the Steam backend also takes the port above it) and its own -savedir, and on crossplay a unique -instanceid.