Linux Survival Basics

Read-only, can be slow

Find the Processes Using Memory

You need a quick process-level view of memory usage.

Command

ps -eo pid,comm,%mem,%cpu --sort=-%mem | head

Before you run this

System impact: Read-only. Can create load on large logs, directories, filesystems, or process tables.

When not to use it: Do not kill a process just because it uses memory; understand its role first.

Expected output

A process table sorted by memory usage.

System impact

Read-only, can be slow. Nothing changes. The command lists processes sorted by memory percentage.

Scope this to the smallest useful path or service on busy systems.

Recovery / rollback: no state is changed.

When to use it

Use this before killing processes or resizing a VPS.

When not to use it

Do not kill a process just because it uses memory; understand its role first.

Watch this command run

Command transcript

This sanitized transcript shows the commands and output shape without exposing host details.

demo@lab:~$

$ ps -eo pid,comm,%mem,%cpu --sort=-%mem | head

    PID COMMAND         %MEM %CPU
     14 ps               0.0  0.0
      1 bash             0.0 33.3
     13 bash             0.0  0.0
     12 timeout          0.0  0.0
     15 head             0.0  0.0

$ free -h

               total        used        free      shared  buff/cache   available
Mem:           125Gi        42Gi       6.3Gi       292Mi        75Gi        83Gi
Swap:             0B          0B          0B

$ df -h

Filesystem      Size  Used Avail Use% Mounted on
/dev/vda1        25G   19G  5G  80% /work
tmpfs            64M     0   64M   0% /dev
shm              64M     0   64M   0% /dev/shm
tmpfs            64M  8.0K   64M   1% /tmp
tmpfs            64M  352K   64M   1% /var
/dev/vda1        25G   19G  5G  80% /work
tmpfs            63G     0   63G   0% /proc/asound
tmpfs            63G     0   63G   0% /proc/acpi
tmpfs            63G     0   63G   0% /proc/scsi
tmpfs            63G     0   63G   0% /sys/firmware
tmpfs            63G     0   63G   0% /sys/devices/virtual/powercap

View commands shown

These are the commands shown in the sanitized transcript.

Commands shown

ps -eo pid,comm,%mem,%cpu --sort=-%mem | head
free -h
df -h

next steps

Related commands

Hosting Operations Can be slow

Find the Processes Burning CPU

A server feels slow, but you need proof before restarting anything.

ps -eo pid,ppid,stat,pcpu,pmem,comm,args --sort=-pcpu | head -n 10

Hosting Operations Can be slow

Find the Processes Eating Memory

Memory pressure can look like a slow app, a stuck deploy, or random crashes.

ps -eo pid,ppid,stat,pcpu,pmem,rss,comm,args --sort=-pmem | head -n 10

Linux Survival Basics Read-only

Check Memory Pressure with free

Linux memory numbers look scary until you know which column matters.

free -h

Linux Survival Basics Read-only

Check Memory Pressure Quickly

See whether memory is actually tight before restarting services.

free -h

Linux Survival Basics Can be slow

Spot OOM Kills in the Kernel Journal

Exit code 137 often means the kernel has something to say.

journalctl -k --since "2 hours ago" --no-pager -o short-iso | grep -Ei 'out of memory|oom|killed process'

Study mapping

Use this as independent command practice: read the notes, predict the output, then compare it with the example before using a real shell.