Linux Process Management Commands

Processes are identified by PID and live in namespaces and cgroups. ps aux lists user processes; pgrep finds PIDs by pattern. Signals like SIGTERM allow graceful shutdown; SIGKILL cannot be handled—use sparingly. nice and ionice adjust scheduling priorities. top and htop show live CPU and memory; systemd-cgtop attributes usage to units.

Signal	Number	Typical use
SIGTERM	15	Polite stop
SIGKILL	9	Force kill hung tasks
SIGHUP	1	Reload configs for daemons

systemctl, ss, sysadmin commands, sudo

kill targets PIDs; killall matches by process name—riskier on shared binaries.

Only when SIGTERM fails and the process is wedged—SIGKILL prevents cleanup and may corrupt data.

Use ps --forest, pstree, or /proc/$pid/task depending on depth needed.

BSD-style columns: all users, user-oriented format, and processes without controlling terminals.

Use systemd-run --scope -p CPUQuota= or cgroups tools; nice only nudges scheduling.

The VM hypervisor took CPU from the guest—check host contention, not app code first.

A child that exited but was not reaped—usually a parent bug; killing the parent may clear it.

Use strace with -p PID for live syscall tracing—expect overhead on production sparingly.

Signal	Number	Typical use
SIGTERM	15	Polite stop
SIGKILL	9	Force kill hung tasks
SIGHUP	1	Reload configs for daemons