helpful_snippets/Linux/processes.md

Process interaction snippets

Find process occupying port

ss -lptn 'sport = :5173'

Output example:

State                 Recv-Q                Send-Q                               Local Address:Port                                 Peer Address:Port                Process                                          
LISTEN                0                     511                                          [::1]:5173                                         [::]:*                    users:(("node",pid=29634,fd=32))

Kill process

sudo kill -[signal] [PID]

Example:

sudo kill -9 29634

Signals:

• SIGTERM (Signal 15). This signal asks for a process to terminate. The process can capture this signal, perform cleanup operations, and then exit. By default, the kill command sends SIGTERM if no other signal is specified.

• SIGKILL (Signal 9). It forcefully kills a process. The process cannot capture or ignore this signal, which results in an immediate termination. It should be used as a last resort when a process doesn’t respond to SIGTERM.

• SIGINT (Signal 2). This is typically sent when you press Ctrl + C in the terminal. It interrupts a process and is usually used to stop a process running in the foreground.

• SIGHUP (Signal 1). Sent to a process when its controlling terminal is closed and often used to reload configuration files.

• SIGQUIT (Signal 3). Causes a process to terminate and produce a core dump file for debugging.

• SIGSTOP (Signal 19). Pauses a process without killing it, similar to pressing Ctrl + Z in the terminal.

• SIGCONT (Signal 18). Continues a process that was stopped by SIGSTOP or Ctrl + Z.