Process Management: CLI vs GUI

macOS offers both command-line tools and graphical applications for managing processes. Understanding both approaches helps you choose the right tool for each situation and troubleshoot process-related issues effectively.

Command-Line Process Tools

ps - Process Status

# BSD syntax (common on macOS)
$ ps aux
USER   PID  %CPU %MEM      VSZ    RSS   TT  STAT STARTED      TIME COMMAND
root     1   0.0  0.1 410148544  18624   ??  Ss   Mon10AM   0:15.23 /sbin/launchd
david  501   0.0  0.2 419826688  35712   ??  S    Mon10AM   0:05.67 /usr/libexec/...

# POSIX syntax
$ ps -ef
  UID   PID  PPID   C STIME   TTY           TIME CMD
    0     1     0   0 Mon10AM ??         0:15.23 /sbin/launchd

# Current user's processes
$ ps -u $USER

# Process tree (requires pstree)
$ brew install pstree
$ pstree

Key ps Columns

Process States

top - Real-Time Process Monitor

# Start top
$ top

# Sort by CPU (default)
$ top -o cpu

# Sort by memory
$ top -o mem

# Show specific user
$ top -U david

# Non-interactive (for scripts)
$ top -l 1 -n 10 -stats pid,command,cpu

htop - Enhanced top

$ brew install htop
$ htop
# Arrow keys to navigate, F9 to kill, q to quit

Signals and kill

# List signals
$ kill -l

# Send SIGTERM (graceful shutdown)
$ kill <pid>
$ kill -15 <pid>
$ kill -TERM <pid>

# Send SIGKILL (force kill)
$ kill -9 <pid>
$ kill -KILL <pid>

# Send SIGHUP (reload configuration)
$ kill -HUP <pid>

# Kill by name
$ pkill -f "process_name"
$ killall process_name

Finding Processes

# Find by name
$ pgrep -l Safari
1234 Safari

# Find by name (full command line)
$ pgrep -fl python

# Find what's using a port
$ lsof -i :8080
COMMAND   PID USER   FD   TYPE             DEVICE SIZE/OFF NODE NAME
python  12345 david  4u   IPv4 0x1234567890      0t0  TCP *:http-alt (LISTEN)

# Find what's using a file
$ lsof /path/to/file

# Find open files by process
$ lsof -p <pid>

# Find processes using network
$ lsof -i

Process Priority

# Run with lower priority (higher nice value)
$ nice -n 10 ./slow_script.sh

# Change running process priority
$ renice 10 -p <pid>

# Run with higher priority (requires root)
$ sudo nice -n -10 ./important_script.sh

Activity Monitor

Activity Monitor is macOS’s graphical process manager, found in /Applications/Utilities/Activity Monitor.app.

Views

Key Features

Process List:

• Sort by any column
• Search/filter processes
• Show all processes vs user processes

Process Information (double-click process):

• Open files and ports
• Memory map
• Statistics
• Parent process

Actions (select process, use toolbar or View menu):

• Quit: Sends SIGTERM
• Force Quit: Sends SIGKILL
• Sample: Creates stack trace

Activity Monitor from CLI

# Open Activity Monitor
$ open -a "Activity Monitor"

# Get same data as Activity Monitor
$ top -l 1 -n 0 -stats pid,command,cpu,mem

# Sample a process (like Activity Monitor's Sample)
$ sample <pid> 5  # 5 second sample

Comparing CLI and GUI

Process Monitoring Tools

vm_stat - Virtual Memory

$ vm_stat
Mach Virtual Memory Statistics: (page size of 16384 bytes)
Pages free:                               41203.
Pages active:                            385918.
Pages inactive:                          347108.
Pages speculative:                        11276.
Pages wired down:                         96482.
...

# Continuous monitoring
$ vm_stat 1  # Every 1 second

iostat - I/O Statistics

$ iostat
              disk0       cpu    load average
    KB/t  tps  MB/s  us sy id   1m   5m   15m
   25.67   12  0.30   3  2 95  2.07 2.15 2.10

# Continuous
$ iostat 1

fs_usage - File System Activity

# Monitor file system calls (requires root)
$ sudo fs_usage

nettop - Network Top

# Monitor network connections per process
$ nettop

Practical Examples

Find and Kill Runaway Process

# Find high CPU process
$ ps aux --sort=-%cpu | head -5

# Or interactively
$ top
# Press 'q' when found

# Kill it
$ kill <pid>
# If unresponsive
$ kill -9 <pid>

Find Memory Hog

$ ps aux --sort=-%mem | head -10

# Or in top
$ top -o mem

Monitor Specific Process

# Watch a process
$ while true; do ps -p <pid> -o %cpu,%mem,rss; sleep 1; done

# Or use watch
$ brew install watch
$ watch -n 1 "ps -p <pid> -o %cpu,%mem,rss"

Debug Hanging Process

# Sample the process
$ sample <pid> 10 -f /tmp/sample.txt

# View open files
$ lsof -p <pid>

# View system calls (requires SIP adjustment)
$ sudo dtruss -p <pid>

Summary

Process management tools:

Best practices:

• Use top or Activity Monitor for interactive monitoring
• Use ps for scripting and one-time checks
• Always try kill before kill -9
• Use lsof to find what’s using resources