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killall Command on ChromeOS Linux Environment

The killall command is a powerful utility used to terminate processes by name rather than by Process ID (PID). Unlike the kill command, which requires a PID, killall simplifies process management by targeting processes with the same name. On ChromeOS Linux (Crostini), killall is particularly useful for managing multiple instances of the same process.

Syntax

The basic syntax of the killall command is:

killall [options] process_name

Key Components:

  • process_name: The name of the process to terminate.
  • options: Modify the behavior of the command.

Examples of Usage

Terminate a Process by Name

To terminate all processes with a specific name, such as chrome:

killall chrome

This sends the default SIGTERM signal to all chrome processes.

Force Terminate Processes

If processes do not respond to SIGTERM, use the -9 option to send the SIGKILL signal:

killall -9 chrome

Send a Specific Signal

To send a different signal to a process, specify it with the -s option or use its signal number:

killall -s HUP myapp

or:

killall -s 1 myapp

Kill Processes Belonging to a Specific User

To terminate processes owned by a specific user, use the -u option:

killall -u username process_name

Ignore Case Sensitivity

Use the -I option to ignore case when matching process names:

killall -I PROCESS_NAME

Dry Run Mode

Simulate the command to see which processes would be terminated without killing them:

killall -v --dry-run process_name

Options

Commonly Used Options

  • -s signal: Specify the signal to send (e.g., SIGTERM, SIGKILL).
  • -u user: Restrict to processes owned by a specific user.
  • -v: Verbose mode, providing detailed output about the command’s actions.
  • -I: Ignore case when matching process names.
  • --dry-run: Simulate the command without terminating any processes.
  • -q: Suppress output.

Finding Process Names

Before using killall, ensure you know the exact name of the process to avoid unintended terminations. Use one of the following methods:

Using ps

List all running processes:

ps aux

Filter for a specific process:

ps aux | grep process_name

Using pgrep

Find process names and their PIDs:

pgrep -l process_name

Using top or htop

Interactive tools like top or htop allow you to view running processes and their details.

Troubleshooting

Command Not Found

If killall is not available, install it as part of the psmisc package:

sudo apt update
sudo apt install psmisc

Permission Denied

If you encounter permission errors, use sudo to execute killall with administrative privileges:

sudo killall process_name

Process Not Found

Ensure the process name is correct and matches exactly. Use -I to ignore case sensitivity if needed.

Best Practices

  1. Verify Process Names: Use tools like ps or pgrep to confirm process names before using killall.
  2. Be Cautious with -I: Ignoring case sensitivity can lead to unintended terminations.
  3. Test with --dry-run: Simulate the command to ensure accuracy before terminating processes.
  4. Use Signals Appropriately: Attempt graceful termination with SIGTERM before resorting to SIGKILL.

The killall command is an efficient tool for managing processes by name in the ChromeOS Linux environment. Its flexibility and simplicity make it a valuable addition to your system administration toolkit.