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

# 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

# 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

# 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)

# 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

# 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

# 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

# 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 "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"

# 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

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 \

# 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

# 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

# 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

# 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

# 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

# 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

# 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)

# 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

# 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

# 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)

# Count files by extension
find . -type f | sed 's/.*\.//' | sort | uniq -c | sort -rn
 
# Find largest files
du -a