Bash & Linux untuk Developer Cheat Sheet

# Print working directory
pwd
 
# List files
ls                    # basic
ls -la                # detail + hidden files
ls -lh                # human-readable sizes
ls -lt                # sort by modification time
ls -ltr               # reverse sort (oldest first)
ls -R                 # recursive
 
# Change directory
cd /path/to/dir       # absolute
cd ../..              # naik 2 level
cd ~                  # ke home directory
cd -                  # ke directory sebelumnya
cd                    # ke home directory

# Create files
touch file.txt                    # buat file kosong
echo "hello" > file.txt           # tulis ke file
echo "line 2" >> file.txt         # append ke file
 
# Create directories
mkdir new-dir
mkdir -p path/to/nested/dir       # buat parent dirs sekaligus
mkdir dir1 dir2 dir3              # multiple dirs
 
# Copy
cp file.txt backup.txt
cp -r folder/ backup/             # recursive (folder)
cp -i file.txt dest/              # interactive (prompt sebelum overwrite)
cp -v file.txt dest/              # verbose
 
# Move/rename
mv old-name.txt new-name.txt
mv file.txt /other/path/
mv -i file.txt dest/              # prompt sebelum overwrite
 
# Delete
rm file.txt
rm -r folder/                     # recursive
rm -rf folder/                    # force, no prompt (HATI-HATI)
rm -i file.txt                    # confirm sebelum hapus

# cat: baca seluruh file
cat file.txt
cat -n file.txt                   # dengan line numbers
 
# head: baca N baris pertama
head file.txt                     # default 10 baris
head -n 50 file.txt               # 50 baris
head -c 1000 file.txt             # 1000 bytes pertama
 
# tail: baca N baris terakhir
tail file.txt                     # default 10 baris
tail -n 50 file.txt               # 50 baris terakhir
tail -f app.log                   # follow (real-time)
tail -f -n 100 app.log            # mulai dari 100 baris terakhir, follow
 
# less: paginated viewer (press q untuk keluar)
less file.txt

# Basic search
grep "pattern" file.txt
grep -i "pattern" file.txt        # case insensitive
grep -r "pattern" /path/          # recursive
grep -v "pattern" file.txt        # inverse (lines WITHOUT pattern)
grep -n "pattern" file.txt        # dengan line numbers
grep -c "pattern" file.txt        # count matches
grep -w "word" file.txt           # whole word match
grep -E "regex" file.txt          # extended regex (alias egrep)
grep -o "pattern" file.txt        # only matching part
grep -A 3 "error" log.txt         # 3 lines After match
grep -B 3 "error" log.txt         # 3 lines Before match
grep -C 3 "error" log.txt         # 3 lines Context (before + after)
grep --color=auto "pattern" file  # highlight match

# Substitute (replace)
sed 's/old/new/' file.txt              # replace first occurrence per line
sed 's/old/new/g' file.txt             # replace all (global)
sed 's/old/new/gi' file.txt            # global + case insensitive
sed -i 's/old/new/g' file.txt          # edit file in-place
sed -i.bak 's/old/new/g' file.txt      # in-place + backup
 
# Delete lines
sed '/pattern/d' file.txt              # delete lines matching pattern
sed '5d' file.txt                      # delete line 5
sed '1,5d' file.txt                    # delete lines 1-5
 
# Print specific lines
sed -n '5,10p' file.txt                # print lines 5-10
sed -n '/start/,/end/p' file.txt       # print between patterns

# Print specific column
awk '{print $2}' file.txt              # column 2
awk '{print $1, $3}' file.txt          # columns 1 and 3
awk -F',' '{print $1}' data.csv        # CSV: split by comma
 
# Conditional
awk '$3 > 100' file.txt                # lines where column 3 > 100
awk 'NR > 1' file.txt                  # skip header row
awk '/error/ {print}' log.txt          # lines containing "error"
 
# Calculations
awk '{sum += $1} END {print sum}' nums.txt
awk '{sum += $3; count++} END {print sum/count}' data.txt
 
# Multiple conditions
awk '$2 == "active" && $3 > 1000' users.txt

# By delimiter
cut -d',' -f2 data.csv                 # field 2 dari CSV
cut -d: -f1 /etc/passwd                # usernames dari passwd
 
# By character position
cut -c1-10 file.txt                    # chars 1-10
cut -c5- file.txt                      # from char 5 to end

# Sort
sort file.txt                          # alphabetical
sort -n numbers.txt                    # numerical
sort -rn numbers.txt                   # reverse numerical
sort -t',' -k2 data.csv                # sort by field 2 (comma delimited)
sort -u file.txt                       # unique (sort + dedupe)
 
# uniq (harus sort dulu)
sort file.txt | uniq                   # remove duplicates
sort file.txt | uniq -c                # count occurrences
sort file.txt | uniq -d                # show only duplicates
sort file.txt | uniq -u                # show only unique lines

# Replace characters
echo "Hello" | tr 'a-z' 'A-Z'          # HELLO
echo "hello world" | tr ' ' '-'        # hello-world
 
# Delete characters
echo "h,e,l,l,o" | tr -d ','           # hello
 
# Squeeze repeats
echo "hello    world" | tr -s ' '      # hello world

echo "log entry" | tee -a logfile.txt  # append to file AND print
command | tee output.txt               # save output + see it

# By name
find . -name "*.js"
find . -name "*.test.ts"
find . -iname "*.JS"                   # case insensitive
find /home -name "*.log"
 
# By type
find . -type f -name "*.md"            # files only
find . -type d -name "node_modules"    # directories only
 
# By size
find . -size +100M                     # larger than 100MB
find . -size -1k                       # smaller than 1KB
 
# By modification time
find . -mtime -1                       # modified in last 24 hours
find . -mtime +7                       # older than 7 days
find . -mmin -30                       # modified in last 30 minutes
 
# By permission
find . -perm 777
find . -type f -perm 600
 
# Execute command on each result
find . -name "*.log" -exec rm {} \;
find . -name "*.js" -exec wc -l {} \;
find . -name "*.js" -exec grep "TODO" {} +

# Numeric
chmod 755 file.sh         # rwxr-xr-x (owner: all, group: rx, other: rx)
chmod 644 file.txt        # rw-r--r-- (owner: rw, group: r, other: r)
chmod 600 .ssh/id_rsa     # rw------- (owner only)
chmod 777 folder/         # rwxrwxrwx (everyone full access)
 
# Symbolic
chmod +x script.sh        # add execute
chmod -w file.txt         # remove write
chmod u+x script.sh       # user: add execute
chmod g+w file.txt        # group: add write
chmod o-r file.txt        # other: remove read
chmod a+r file.txt        # all: add read
chmod -R 755 folder/      # recursive

chown user file.txt               # change owner
chown user:group file.txt         # change owner + group
chown -R user:group folder/       # recursive

# Basic GET
curl https://api.example.com
curl -o output.json https://api.example.com/data    # save to file
 
# POST dengan data
curl -X POST https://api.example.com/users \
  -H "Content-Type: application/json" \
  -d '{"name": "Galih", "email": "hi@galihpratama.com"}'
 
# Headers
curl -H "Authorization: Bearer token123" https://api.example.com/protected
 
# Verbose (lihat request + response headers)
curl -v https://example.com
 
# Follow redirects
curl -L https://short.url/abc
 
# Download dengan progress bar
curl -O https://example.com/file.zip
curl -L -O https://example.com/large-file.iso
 
# Authentication
curl -u username:password https://api.example.com/
curl --cert client.pem https://secure.example.com/
 
# Set timeout
curl --max-time 30 https://slow-api.example.com/
 
# Multiple URLs
curl -O https://example.com/file1.txt -O https://example.com/file2.txt
 
# Download resume
curl -C - -O https://example.com/large-file.zip
 
# Check headers only
curl -I https://example.com

# Download file
wget https://example.com/file.zip
wget -O custom-name.zip https://example.com/file.zip
 
# Recursive (mirror website)
wget -r -l 2 https://example.com/
 
# Continue partial download
wget -c https://example.com/large-file.zip
 
# Background download
wget -b https://example.com/large-file.zip
 
# Download from file list
wget -i urls.txt

# Check connectivity
ping -c 4 google.com
 
# DNS lookup
dig example.com
dig +short example.com
nslookup example.com
 
# Trace route
traceroute google.com
 
# Check port
nc -zv example.com 443          # check if port 443 is open
nc -zv -w5 example.com 8080     # with 5s timeout
 
# Show open ports
ss -tlnp                        # TCP listening ports
netstat -tlnp                   # legacy alternative
 
# Show network interfaces
ip addr
ifconfig                        # legacy
 
# Show routing table
ip route

# ps
ps aux                          # semua proses
ps aux | grep node              # cari proses node
ps -ef | grep python
 
# top / htop
top                             # interactive process viewer
htop                            # better version (install dulu)

# By PID
kill 12345                      # SIGTERM (graceful)
kill -9 12345                   # SIGKILL (force)
kill -15 12345                  # SIGTERM (explicit)
 
# By name
killall node
pkill -f "node server.js"
 
# Graceful shutdown dengan signal names
kill -SIGTERM 12345
kill -SIGINT 12345              # Ctrl+C
kill -SIGHUP 12345              # reload config

# Run in background
command &
 
# Run even after logout
nohup node server.js &
 
# Jobs
jobs                            # list background jobs
fg                              # bring last job to foreground
fg %1                           # bring job 1 to foreground
bg %2                           # resume job 2 in background
Ctrl+Z                          # suspend current process
Ctrl+C                          # kill current process

# Disk usage
df -h                           # filesystem usage
du -sh /folder                  # folder size
du -sh *                        # size of items in current dir
du -h --max-depth=1             # one level deep
 
# Memory
free -h                         # RAM usage
vmstat 1                        # virtual memory stats every 1s
 
# CPU
uptime                          # load average
nproc                           # number of CPU cores
lscpu                           # CPU info
 
# System info
uname -a                        # kernel info
hostname                        # machine name
date                            # current date/time
whoami                          # current user

# Set untuk session ini
export NODE_ENV=production
export DATABASE_URL="postgresql://localhost:5432/mydb"
export PATH=$PATH:/custom/path
 
# Baca variable
echo $HOME
echo $PATH
printenv                        # semua environment variables
env                             # alternative
 
# Load dari file
source .env                     # atau
. .env
 
# Set untuk satu command saja
NODE_ENV=test node app.js
 
# Unset
unset MY_VAR

# Pipe: output command A jadi input command B
cat file.txt | grep "error"
ps aux | grep node | grep -v grep
 
# Redirect output
command > file.txt              # stdout ke file (overwrite)
command >> file.txt             # stdout ke file (append)
command 2> error.log            # stderr ke file
command > out.txt 2>&1          # stdout + stderr ke file yang sama
command &> combined.log         # stdout + stderr (bash shortcut)
 
# Redirect input
command < input.txt
mysql < schema.sql
 
# /dev/null (black hole)
command > /dev/null 2>&1        # buang semua output
command 2>/dev/null             # buang stderr saja
 
# Process substitution
diff <(ls dir1) <(ls dir2)      # compare output dua commands

# Connect
ssh user@server.com
ssh -p 2222 user@server.com             # custom port
ssh -i ~/.ssh/custom_key user@server    # custom key
 
# Run command remote
ssh user@server "ls -la /var/log"
ssh user@server "df -h"
 
# Port forwarding (local tunnel)
ssh -L 8080:localhost:80 user@server    # localhost:8080 -> server:80
ssh -L 5432:db.internal:5432 user@bastion
 
# Reverse port forwarding
ssh -R 8080:localhost:80 user@server
 
# Dynamic port forwarding (SOCKS proxy)
ssh -D 1080 user@server
 
# Copy files
scp file.txt user@server:/path/to/dest/
scp user@server:/path/to/file.txt ./
scp -r folder/ user@server:/path/
 
# rsync (lebih efisien buat transfer besar)
rsync -avz --progress folder/ user@server:/dest/
rsync -avz --delete src/ user@server:dest/    # mirror (delete extra files)
rsync -avz -e "ssh -p 2222" src/ user@server:dest/

# Generate key pair
ssh-keygen -t ed25519 -C "hi@galihpratama.com"
ssh-keygen -t rsa -b 4096 -C "hi@galihpratama.com"
 
# Copy public key ke server
ssh-copy-id user@server
# atau manual
cat ~/.ssh/id_ed25519.pub | ssh user@server "mkdir -p ~/.ssh && cat >> ~/.ssh/authorized_keys"
 
# SSH config (~/.ssh/config)
Host myserver
  HostName server.example.com
  User galih
  Port 2222
  IdentityFile ~/.ssh/my_key
 
# Setelah itu tinggal
ssh myserver

# Edit crontab
crontab -e                     # edit
crontab -l                     # list current jobs
crontab -r                     # remove all jobs
 
# Format: minute hour day-of-month month day-of-week command
# Jadwal contoh:
# ┌──────── minute (0-59)
# │ ┌────── hour (0-23)
# │ │ ┌──── day of month (1-31)
# │ │ │ ┌── month (1-12)
# │ │ │ │ ┌ day of week (0-7, 0 dan 7 = Sunday)
# │ │ │ │ │
# * * * * * command
 
*/5 * * * * /script/backup.sh                    # setiap 5 menit
0 2 * * * /script/cleanup.sh                     # jam 2 pagi setiap hari
0 0 * * 0 /script/weekly-report.sh               # midnight setiap minggu
0 9 * * 1-5 /script/workday-task.sh              # jam 9 pagi, Senin-Jumat
0 0 1 * * /script/monthly-report.sh              # tanggal 1 setiap bulan

# Count files by extension
find . -type f | sed 's/.*\.//' | sort | uniq -c | sort -rn
 
# Find largest files
du -a /path | sort -rn | head -20
 
# Kill process on specific port
kill -9 $(lsof -t -i:3000)
 
# Extract column from CSV dan count unique
cut -d',' -f3 data.csv | sort | uniq -c | sort -rn
 
# Replace text in multiple files
find . -name "*.js" -exec sed -i 's/oldName/newName/g' {} +
 
# Download dan extract tarball
curl -sL https://example.com/file.tar.gz | tar xz
 
# Create password
openssl rand -base64 32
 
# JSON pretty print
echo '{"a":1,"b":2}' | python3 -m json.tool
 
# Monitor file changes
watch -n 1 ls -la /path
 
# Quick HTTP server
python3 -m http.server 8000
npx serve -p 3000
 
# Send notification when command selesai
long-command; notify-send "Done!"