Linux信號是進(jìn)程間通信或響應(yīng)外部事件的機(jī)制，常見信號包括SIGHUP、SIGINT、SIGTERM和SIGKILL。 1. SIGHUP用於通知進(jìn)程重載配置或終端斷開，如重啟服務(wù)或日誌輪轉(zhuǎn)；2. SIGINT通過Ctrl C發(fā)送，用於中斷前臺任務(wù)；3. SIGTERM是默認(rèn)終止信號，允許進(jìn)程優(yōu)雅退出；4. SIGKILL強(qiáng)制終止進(jìn)程，僅在無響應(yīng)時使用。正確選擇信號可避免數(shù)據(jù)損壞和服務(wù)中斷。

Linux signals are a way for processes to communicate with each other or respond to external events. They're like messages sent to a running program to tell it something important has happened. You might not see them in action every day, but when things go wrong or you're managing services, knowing how they work can save you time and headaches.

Here's a breakdown of some of the most common signals: SIGHUP , SIGINT , SIGTERM , and SIGKILL .

What is SIGHUP and when is it used?

SIGHUP stands for "signal hang up." Originally, it was sent to a process when the controlling terminal disconnected — like if you were SSHed into a server and your connection dropped. These days, it's often used to tell a process to reload its configuration files without stopping.

For example:

• Restarting a web server without downtime
• Telling a logging service to rotate logs

If you want to send a SIGHUP manually, you can do it with kill -HUP <pid></pid> .

A common use case is sending SIGHUP to a background process that was started from a terminal session after closing that session. If the process isn't set up to ignore the signal, it might terminate unless it was started with something like nohup or run inside a screen/tmux session.

SIGINT – How does it stop processes?

SIGINT means "interrupt signal." It's what gets sent when you press Ctrl C in your terminal. It tells a running program to stop what it's doing, usually allowing it to clean up resources before exiting.

Some key points about SIGINT:

• It can be caught or ignored by programs.
• Most command-line tools will exit gracefully when receiving it.
• Background jobs can still receive this signal if they're tied to the terminal.

If you've ever typed a command and then canceled it with Ctrl C, you've used SIGINT.

SIGTERM – The polite way to ask a process to quit

SIGTERM is the default signal sent by the kill command. It's the standard way to request that a process shut down. Unlike SIGKILL, it gives the process a chance to clean up — close files, save state, or finish handling current requests.

This matters because:

• Services like databases or web servers need time to shut down properly
• Killing them with something stronger than SIGTERM could leave data in an inconsistent state

You can send it using kill <pid></pid> (without any extra flags) or kill -TERM <pid></pid> .

Some applications have custom behavior for SIGTERM — for example, telling a long-running script to log progress and exit cleanly.

SIGKILL – The last resort

SIGKILL is the big hammer. It forces a process to stop immediately. There's no chance for cleanup, no graceful exit — just instant termination. This signal cannot be caught or ignored by a process.

Use SIGKILL only when:

• A process isn't responding to SIGTERM
• It's stuck and consuming system resources
• You're sure it's safe to kill instantly

To send it: kill -9 <pid></pid>

Be careful with SIGKILL. For example, killing a database process this way might corrupt data if it was writing to disk at the time.

So, to recap:

• Use SIGHUP to reload config or reconnect sessions
• Use SIGINT to cancel foreground tasks
• Prefer SIGTERM for clean shutdowns
• Save SIGKILL for stubborn processes

These signals are basic tools in Linux system management. Knowing which one to use — and when — helps avoid unnecessary crashes or data loss.

基本上就這些。

以上是Linux信號是什麼，例如Sighup，Sigint，Sigterm和Sigkill？的詳細(xì)內(nèi)容。更多資訊請關(guān)注PHP中文網(wǎng)其他相關(guān)文章！