When managing servers or debugging performance issues, system administrators often need to monitor specific processes like Java applications, Tomcat, Redis, MySQL, or MongoDB. The standard top command shows all running processes, which can be overwhelming when you're only interested in a few critical services.

By default, top displays all processes sorted by CPU usage:

top

This gives you a dynamic view of system activity, but finding your target processes requires manual scanning.

While top is running, you can use these interactive commands:

• Press 'o' or 'O' to add filter criteria
• Type 'COMMAND=java' to show only Java processes
• Use '|' for OR conditions: 'COMMAND=java|COMMAND=tomcat'

For a more permanent solution, use these approaches:

Method 1: Using pgrep with top

top -p $(pgrep -d',' java tomcat redis mysql mongod)

This shows only processes matching the specified names.

Method 2: Creating a Custom Top Configuration

Add this to your ~/.toprc file:

RCfile for "top with windows"       # shameless bullshit line
Id:a, Mode_altscr=0, Mode_irixps=1, Delay_time=3.0, Curwin=0
Def     fieldscur=AEHIOQTWKNMbcdfgjplrsuvyzX
        winflags=62777, sortindx=10, maxtasks=0
        summclr=6, msgsclr=6, headclr=7, taskclr=6
Job     fieldscur=ABcefgjlrstuvyzMKNHIWOPQDX
        winflags=62777, sortindx=0, maxtasks=0
        summclr=2, msgsclr=2, headclr=7, taskclr=6

Then run top with:

top -c -p $(pgrep -d',' java tomcat redis mysql mongod)

Consider these alternatives if you need more advanced filtering:

htop

htop --filter=java,tomcat,redis,mysql,mongod

Custom Script with Watch

Create a script called mytop:

#!/bin/bash
watch -n 1 "ps aux | grep -E 'java|tomcat|redis|mysql|mongod'"

Make it executable and run:

chmod +x mytop
./mytop

For more precise filtering, you can monitor by:

• Process owner: top -u mysql
• Process group: top -g redis
• CPU threshold: top -b -n 1 | awk '$9 > 50'

For production environments, consider setting up monitoring with:

while true; do
    clear
    top -b -n 1 -p $(pgrep -d',' java tomcat redis mysql mongod) | head -n 20
    sleep 2
done

---

When running top in Linux, the default view shows all active processes. For developers managing specific services like Java applications, Tomcat, Redis, MySQL, or MongoDB, this can be overwhelming. Here's how to filter top to focus only on the processes you care about.

The most straightforward method is using process IDs with the -p flag:

# First get PIDs of your target processes
pgrep -f 'java\|tomcat\|redis-server\|mysqld\|mongod' | tr '\n' ','

# Then run top with the filtered PIDs
top -p $(pgrep -f 'java\|tomcat\|redis-server\|mysqld\|mongod' | tr '\n' ',')

Once top is running, you can apply filters interactively:

1. Press 'o' (lowercase) to add a filter
2. Enter: COMMAND=java || COMMAND=tomcat || COMMAND=redis-server || COMMAND=mysqld || COMMAND=mongod
3. Press Enter to apply

For frequent use, create a .toprc configuration file:

cat > ~/.toprc << 'EOF'
RCfile for "top with windows"       # shameless bullshit line
Id:a, Mode_altscr=0, Mode_irixps=1, Delay_time=3.0, Curwin=0
Def     fieldscur=AEHIOQTWKNMbcdfgGjlmrsuvySZ
        winflags=848024, sortindx=10, maxtasks=0
        summclr=6, msgsclr=6, headclr=6, taskclr=6
Job     fieldscur=ABcefgjlmyzMLONPHIKRWVZ
        winflags=62777, sortindx=0, maxtasks=0
        summclr=6, msgsclr=6, headclr=6, taskclr=6
Filter  fieldscur=
        winflags=130944, sortindx=10, maxtasks=50
        summclr=1, msgsclr=1, headclr=1, taskclr=1
        filter=COMMAND=java\|tomcat\|redis-server\|mysqld\|mongod
EOF

If you can install htop, it offers superior filtering capabilities:

# Install htop
sudo apt install htop  # Debian/Ubuntu
sudo yum install htop  # RHEL/CentOS

# Run with filter
htop --filter='java|tomcat|redis|mysql|mongo'

For continuous monitoring, combine with watch:

watch -n 2 "top -b -n 1 -p \$(pgrep -f 'java\|tomcat\|redis-server\|mysqld\|mongod' | tr '\n' ',') | head -20"

For systemd-managed services, you might prefer:

watch -n 2 "systemctl status tomcat redis mysql mongod --no-pager"