# Cheatsheet & Examples: kill

The `kill` command is a utility in Unix-like operating systems used to send signals to processes. Signals are a form of inter-process communication that can be used to terminate, suspend, or otherwise control processes.

## Terminate a Process (SIGTERM)

Example Usage:
`kill <PID>`

What it does:
Sends the SIGTERM signal (termination signal) to the process with the specified process ID (PID), requesting it to terminate gracefully.

Command-line Arguments Explained:

- `<PID>`: The process ID (a numerical identifier) of the process you want to terminate.

## Forcefully Terminate a Process (SIGKILL)

Example Usage:
`kill -9 <PID>` or `kill -KILL <PID>`

What it does:
Sends the SIGKILL signal (kill signal) to the process with the specified PID. This signal immediately terminates the process without allowing it to perform any cleanup operations.  Use this as a last resort, as it can lead to data loss or corruption if the process is in the middle of writing data.

Command-line Arguments Explained:

- `-9` or `-KILL`:  Specifies the signal to send; in this case, SIGKILL, which is signal number 9.
- `<PID>`: The process ID of the process to be terminated.

## Send a Specific Signal

Example Usage:
`kill -<SIGNAL_NUMBER> <PID>` or `kill -s <SIGNAL_NAME> <PID>`

What it does:
Sends a specific signal to the specified process. The signal can be identified by its number or name.

Command-line Arguments Explained:

- `-<SIGNAL_NUMBER>`: Specifies the signal to send, using its numeric value (e.g., `-15` for SIGTERM).
- `-s <SIGNAL_NAME>`: Specifies the signal to send, using its symbolic name (e.g., `-s TERM` or `-s SIGTERM` for the termination signal).
- `<PID>`: The process ID of the target process.

## Suspend a Process (SIGSTOP)

Example Usage:
`kill -STOP <PID>`

What it does:
Sends the SIGSTOP signal, causing the process to pause its execution.  The process can later be resumed with the SIGCONT signal.

Command-line Arguments Explained:

- `-STOP`: Specifies the signal to send (SIGSTOP).
- `<PID>`: The PID of the process to be suspended.

## Resume a Suspended Process (SIGCONT)

Example Usage:
`kill -CONT <PID>`

What it does:
Sends the SIGCONT signal, resuming the execution of a previously suspended process.

Command-line Arguments Explained:

- `-CONT`: Specifies the signal to send (SIGCONT).
- `<PID>`: The PID of the process to resume.

## List Available Signals

Example Usage:
`kill -l`

What it does:
Lists all the available signals that can be used with the `kill` command and their corresponding numeric values.

Command-line Arguments Explained:

- `-l`:  The list flag.