Linux Process Management Cheat Sheet

Updated 2026-05-20

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Linux process management is the set of tools and techniques for inspecting, controlling, and tuning the processes running on a Linux system. Every running program — a web server, a shell, a background cron job — exists as a process with its own PID, memory footprint, scheduling attributes, and signal-response rules. Mastering process management is a core sysadmin and developer skill: it lets you diagnose performance problems, clean up runaway jobs, tune CPU and I/O priority for competing workloads, and write scripts that run reliably even when users disconnect. The non-obvious key insight is that signals are the universal control channel — understanding which signal to send (and when) separates a practitioner from someone who always reaches for kill -9.

What This Cheat Sheet Covers

This topic spans 19 focused tables and 168 indexed concepts. Below is a complete table-by-table outline of this topic, spanning foundational concepts through advanced details.

Table 1: Process Listing with psTable 2: Process State Codes (STAT Column)Table 3: Finding Processes with pgrep and pidofTable 4: Linux Signals ReferenceTable 5: Sending Signals with kill, pkill, and killallTable 6: CPU Priority with nice and reniceTable 7: I/O Priority with ioniceTable 8: Background Execution and Job ControlTable 9: Process Tree Visualization with pstreeTable 10: Tracing System Calls with straceTable 11: Listing Open Files with lsofTable 12: Resource Limits with ulimitTable 13: The /proc Filesystem for Process InspectionTable 14: CPU Affinity and Real-Time SchedulingTable 15: OOM Killer and Memory ProtectionTable 16: Zombie and Orphan ProcessesTable 17: Signal Trapping in Shell ScriptsTable 18: Performance Profiling with perfTable 19: Cgroup-Based Resource Control

Table 1: Process Listing with ps

The ps command is the go-to snapshot tool for seeing what is running on a system. BSD-style (ps aux) and POSIX-style (ps -ef) produce similar output but differ in columns — aux adds %CPU, %MEM, VSZ, RSS, and STAT, while -ef adds PPID (parent PID).

Command	Example	Description
ps aux	`ps aux`	Lists all processes for all users with CPU%, MEM%, VSZ, RSS, and STAT columns (BSD style).
ps -ef	`ps -ef`	Lists all processes in full format including PPID (POSIX/UNIX style).
ps -eo (custom columns)	`ps -eo pid,ppid,ni,pcpu,pmem,comm`	Prints only the user-specified columns; any keyword from `ps --help all` is valid.
ps --sort	`ps -eo pid,pcpu,comm --sort=-%cpu`	Sorts output by a field; prefix with `-` for descending order (e.g. top CPU consumers first).
ps -C (by command name)	`ps -C nginx -o pid=`	Selects processes by exact executable name; suppresses header with `=`.

Table 1: Process Listing with ps

Command	Example	Description
ps aux	`ps aux`	Lists all processes for all users with CPU%, MEM%, VSZ, RSS, and STAT columns (BSD style).
ps -ef	`ps -ef`	Lists all processes in full format including PPID (POSIX/UNIX style).
ps -eo (custom columns)	`ps -eo pid,ppid,ni,pcpu,pmem,comm`	Prints only the user-specified columns; any keyword from `ps --help all` is valid.
ps --sort	`ps -eo pid,pcpu,comm --sort=-%cpu`	Sorts output by a field; prefix with `-` for descending order (e.g. top CPU consumers first).
ps -C (by command name)	`ps -C nginx -o pid=`	Selects processes by exact executable name; suppresses header with `=`.