Essential commands cheatsheet

Keep this open while you work the labs. You do not need to memorize everything — muscle memory comes from repetition.

Navigation

pwd                 # where am I?
ls -la              # list files (incl. hidden)
cd /var/log         # change directory
cd -                # previous directory

Inspect

uname -a            # kernel / arch
whoami              # current user
cat /etc/os-release # distro info
df -h               # disk free
ps aux | head       # processes

Read & write

echo hello > /tmp/a.txt
cat /tmp/a.txt
less /var/log/syslog   # if present — q to quit
wc -l file             # line count

SRE habit

When something is broken: what changed? Check processes, disk, memory, and the freshest logs before restarting anything.