> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify.com/nats-io/nats-server/llms.txt
> Use this file to discover all available pages before exploring further.

# Signals

> Signal handling and process management for NATS server

NATS server supports signal handling for graceful operations like reloading configuration, rotating logs, and shutting down.

## Signal Command

Use the `--signal` flag to send signals to a running NATS server process:

```bash theme={null}
nats-server --signal <signal>[=<pid>]
```

### Signal Format

<ParamField path="signal" type="string" required>
  The signal to send. Available signals: `ldm`, `stop`, `quit`, `term`, `reopen`, `reload`
</ParamField>

<ParamField path="pid" type="string">
  Process identifier. Can be either:

  * A numeric PID (e.g., `1234`)
  * Path to a PID file (e.g., `/var/run/nats-server.pid`)

  If not specified, signals are sent to all nats-server processes.
</ParamField>

## Available Signals

### ldm - Log Debug and Memory

Dumps current goroutine stack traces and memory stats to the log.

**Usage:**

```bash theme={null}
# Using PID file
nats-server --signal ldm=/var/run/nats-server.pid

# Using numeric PID
nats-server --signal ldm=12345

# To all nats-server processes
nats-server --signal ldm
```

**Output Location:**

* Written to the configured log file (if `-l` was used)
* Written to stdout if no log file configured

**Use Cases:**

* Debugging deadlocks
* Investigating high memory usage
* Troubleshooting performance issues

### stop - Graceful Shutdown

Initiates graceful shutdown of the server. The server will:

1. Stop accepting new connections
2. Wait for existing clients to disconnect
3. Flush pending messages
4. Exit cleanly

**Usage:**

```bash theme={null}
# Using PID file
nats-server --signal stop=/var/run/nats-server.pid

# Using numeric PID
nats-server --signal stop=12345

# To all nats-server processes
nats-server --signal stop
```

**Equivalent System Signals:**

* `SIGINT` (Ctrl+C)
* `SIGTERM`

### quit - Immediate Shutdown

Immediately terminates the server without graceful cleanup.

**Usage:**

```bash theme={null}
nats-server --signal quit=/var/run/nats-server.pid
```

<Warning>
  Use `quit` only when `stop` fails or immediate termination is required. Prefer `stop` for graceful shutdown.
</Warning>

**Equivalent System Signal:**

* `SIGQUIT`

### term - Terminate

Similar to `stop`, initiates graceful shutdown.

**Usage:**

```bash theme={null}
nats-server --signal term=/var/run/nats-server.pid
```

**Equivalent System Signal:**

* `SIGTERM`

### reopen - Rotate Log File

Reopens the log file. Used for log rotation with external tools like `logrotate`.

**Usage:**

```bash theme={null}
nats-server --signal reopen=/var/run/nats-server.pid
```

**Log Rotation Workflow:**

1. External tool moves/renames the current log file
2. Send `reopen` signal to nats-server
3. Server closes old file handle and opens new log file

**Example with logrotate:**

```bash theme={null}
# /etc/logrotate.d/nats-server
/var/log/nats-server.log {
    daily
    rotate 7
    compress
    delaycompress
    missingok
    notifempty
    postrotate
        nats-server --signal reopen=/var/run/nats-server.pid
    endscript
}
```

**Manual Rotation:**

```bash theme={null}
# Move current log
mv /var/log/nats-server.log /var/log/nats-server.log.1

# Signal server to reopen
nats-server --signal reopen=/var/run/nats-server.pid

# Server now writes to new /var/log/nats-server.log
```

### reload - Reload Configuration

Reloads the server configuration from the config file without restarting.

**Usage:**

```bash theme={null}
nats-server --signal reload=/var/run/nats-server.pid
```

**What Gets Reloaded:**

<Accordion title="Authorization settings">
  * User credentials
  * Permissions
  * Account definitions
</Accordion>

<Accordion title="Logging settings">
  * Log level
  * Debug/trace flags
  * Log file path
</Accordion>

<Accordion title="Cluster settings">
  * Cluster permissions
  * Authorization
</Accordion>

<Accordion title="Monitoring settings">
  * HTTP monitoring port settings
</Accordion>

**What Cannot Be Reloaded:**

* Listen address and port
* Server name
* Cluster URL
* JetStream storage directory
* TLS certificates (requires restart)

**Example:**

```bash theme={null}
# Edit configuration file
vim /etc/nats/nats-server.conf

# Reload configuration
nats-server --signal reload=/var/run/nats-server.pid

# Check logs for reload confirmation
tail -f /var/log/nats-server.log
```

**Output:**

```
[INF] Reloading server configuration
[INF] Reloaded server configuration
```

## Using PID Files

For reliable signal delivery, start the server with a PID file:

```bash theme={null}
# Start server with PID file
nats-server -c nats.conf -P /var/run/nats-server.pid

# Later, send signals using the PID file
nats-server --signal reload=/var/run/nats-server.pid
```

## System Signal Equivalents

You can also send signals directly using standard Unix tools:

```bash theme={null}
# Graceful shutdown
kill -SIGTERM $(cat /var/run/nats-server.pid)
kill -SIGINT $(cat /var/run/nats-server.pid)

# Immediate shutdown
kill -SIGQUIT $(cat /var/run/nats-server.pid)

# Reload configuration (SIGHUP)
kill -SIGHUP $(cat /var/run/nats-server.pid)

# Reopen log file (SIGUSR1)
kill -SIGUSR1 $(cat /var/run/nats-server.pid)

# Log debug and memory (SIGUSR2)
kill -SIGUSR2 $(cat /var/run/nats-server.pid)
```

## Complete Examples

### Production Server with Signal Support

```bash theme={null}
# Start server with PID file
nats-server \
  -c /etc/nats/nats-server.conf \
  -P /var/run/nats-server.pid \
  -l /var/log/nats-server.log

# Reload configuration
nats-server --signal reload=/var/run/nats-server.pid

# Rotate logs
nats-server --signal reopen=/var/run/nats-server.pid

# Graceful shutdown
nats-server --signal stop=/var/run/nats-server.pid
```

### Debug Running Server

```bash theme={null}
# Dump goroutines and memory stats
nats-server --signal ldm=/var/run/nats-server.pid

# Check the log output
tail -100 /var/log/nats-server.log
```

### Update Authorization

```bash theme={null}
# Edit config to add new user
vim /etc/nats/nats-server.conf

# Reload without restart
nats-server --signal reload=/var/run/nats-server.pid

# New user can connect immediately
```

### Emergency Shutdown

```bash theme={null}
# Try graceful shutdown first
nats-server --signal stop=/var/run/nats-server.pid

# Wait 30 seconds
sleep 30

# If still running, force quit
if ps -p $(cat /var/run/nats-server.pid) > /dev/null; then
    nats-server --signal quit=/var/run/nats-server.pid
fi
```

## Systemd Integration

For systemd-managed servers, signals are handled automatically:

```ini theme={null}
# /etc/systemd/system/nats-server.service
[Unit]
Description=NATS Server
After=network.target

[Service]
Type=simple
ExecStart=/usr/local/bin/nats-server -c /etc/nats/nats-server.conf -P /var/run/nats-server.pid
ExecReload=/usr/local/bin/nats-server --signal reload=/var/run/nats-server.pid
KillMode=mixed
KillSignal=SIGTERM
Restart=on-failure

[Install]
WantedBy=multi-user.target
```

Usage:

```bash theme={null}
# Start service
sudo systemctl start nats-server

# Reload configuration
sudo systemctl reload nats-server

# Graceful stop
sudo systemctl stop nats-server

# Restart
sudo systemctl restart nats-server
```

## Related Options

* [Server Options](/cli/server-options) - PID file configuration
* [Logging Options](/cli/logging-options) - Log file and rotation settings