Cheatsheet

# Files + dirs
ls -lah; find . -maxdepth 2 -type d
tree -L 2
du -sh */ | sort -h        # size by dir
df -h                       # disk free

# Permissions + ownership
chmod 644 file; chmod 755 dir
chown -R user:group path

# Text
grep -rn 'TODO' src/
grep -E 'foo|bar' file
rg 'pattern'                # ripgrep, faster
sed -i.bak 's/old/new/g' file
awk -F, '{ print $1, $3 }' file.csv

# JSON
jq '.users[] | select(.tier == "pro") | .email' users.json
jq -r '.[].id' < items.json | xargs -I {} curl https://api/{}

# Processes
ps -ef | grep node
pgrep -fl node
htop                        # interactive
lsof -iTCP:3000 -sTCP:LISTEN
kill -TERM <pid>; kill -9 <pid>

# Networking
ss -tlnp                    # listening sockets
curl -fsS https://example.com -o body.html -D headers.txt
curl -X POST -H 'content-type: application/json' -d '{"a":1}' http://localhost:3000/
dig +short example.com
traceroute example.com

# Compression
tar -czf out.tar.gz dir/
tar -xzf out.tar.gz
zip -r out.zip dir/ ; unzip out.zip

# Archives + sync
rsync -aHAXP src/ user@host:/dst/
scp file user@host:/path/

# History
history | grep ssh
!! ; !$ ; !*

# Productivity
alias ll='ls -lah'
alias gs='git status'
alias gco='git checkout'
alias k='kubectl'

# Quick math
echo $((1 + 2 * 3))
python3 -c 'print(2**32)'

# Find slow queries
last | head -20
journalctl -u myapp -n 100 --no-pager
journalctl -u myapp -f       # follow

# One-liners
# Top 10 IPs by hits in nginx log
awk '{ print $1 }' access.log | sort | uniq -c | sort -rn | head

# Disk hogs
du -ah / 2>/dev/null | sort -rh | head -20

# Find files modified in last 24h
find . -type f -mtime -1

# Convert timestamps
date -u +%FT%TZ
date -d '@1718000000' +'%F %T'

ls cd pwd mkdir rm cp mv cat less grep find sed awk ps top kill jobs curl ssh chmod chown sort uniq