# Basic wildcards
ls *.txt                    # All files ending with .txt
ls file*.txt               # Files starting with "file" and ending with .txt
ls file?.txt               # Single character wildcard (file1.txt, filea.txt)
ls file[1-3].txt           # Files with numbers 1, 2, or 3
ls file[abc].txt           # Files with letters a, b, or c
ls *.{jpg,png,gif}         # Multiple extensions

# Copy all images to a backup directory
cp *.{jpg,jpeg,png,gif} ~/Pictures/backup/

# Remove all temporary files
rm *.tmp *.temp

# List all configuration files
ls *.conf *.cfg *.ini

# Move all documents to Documents folder
mv *.{doc,docx,pdf,txt} ~/Documents/

# Count all source code files
wc -l *.{c,cpp,h,py,js}

# Preserve timestamps, permissions, and ownership
cp -p source.txt destination.txt

# Copy recursively with all attributes
cp -a source_directory/ destination_directory/

# Interactive copy (confirm overwrites)
cp -i *.txt ~/backup/

# Verbose copy (show what's being copied)
cp -v *.log /var/log/backup/

# Move with backup (if destination exists)
mv --backup=numbered file.txt ~/Documents/

# Interactive move (confirm overwrites)
mv -i *.txt ~/Documents/

# Move only if source is newer
mv -u *.txt ~/Documents/

find [path] [expression] [action]

# Find files by exact name
find /home/username -name "config.txt"

# Case-insensitive search
find /home/username -iname "CONFIG.TXT"

# Find files with patterns
find /home/username -name "*.py"
find /home/username -name "test*"

# Find files NOT matching pattern
find /home/username -not -name "*.tmp"

# Find only directories
find /home/username -type d

# Find only regular files
find /home/username -type f

# Find symbolic links
find /home/username -type l

# Find executable files
find /home/username -type f -executable

# Files larger than 100MB
find /home/username -size +100M

# Files smaller than 1KB
find /home/username -size -1k

# Files exactly 50MB
find /home/username -size 50M

# Empty files
find /home/username -empty

# Modified in last 7 days
find /home/username -mtime -7

# Modified more than 30 days ago
find /home/username -mtime +30

# Accessed in last 24 hours
find /home/username -atime -1

# Changed in last hour
find /home/username -ctime -1

# Large image files modified recently
find ~/Pictures -name "*.jpg" -size +5M -mtime -7

# Python files in project directories
find ~/projects -name "*.py" -type f

# Executable files owned by current user
find /usr/local/bin -type f -executable -user $(whoami)

# Configuration files not accessed in 6 months
find /etc -name "*.conf" -atime +180

# Delete all .tmp files
find /tmp -name "*.tmp" -delete

# Execute command on each found file
find ~/Documents -name "*.txt" -exec wc -l {} \;

# Move all .log files to archive
find /var/log -name "*.log" -exec mv {} /archive/ \;

# Change permissions of all .sh files
find ~/scripts -name "*.sh" -exec chmod +x {} \;

# List details of large files
find /home/username -size +100M -exec ls -lh {} \;

# Update the locate database (run as root)
sudo updatedb

# Find files containing "python" in the name
locate python

# Case-insensitive search
locate -i PYTHON

# Limit results to 10
locate -l 10 "*.conf"

# Count matching files
locate -c "*.py"

# Show only existing files (database might be outdated)
locate -e "config"

# Find the location of a command
which python3
which gcc

# Find command, source, and manual locations
whereis python3
whereis gcc

# Find all instances of a command
which -a python

~/projects/
├── web-development/
│   ├── project1/
│   │   ├── src/
│   │   ├── tests/
│   │   ├── docs/
│   │   └── config/
│   └── project2/
├── python-scripts/
├── learning/
└── archived/

~/admin/
├── scripts/
│   ├── backup/
│   ├── monitoring/
│   └── maintenance/
├── configs/
├── logs/
└── documentation/

# Good naming examples
backup_2025-07-19.tar.gz
web_server_config.conf
user_management_script.py
project_documentation_v2.md

# Avoid these patterns
My File.txt           # Spaces
CONFIG.TXT           # All caps
temp123              # Non-descriptive
file (copy)          # Parentheses

# Create tar archive
tar -cvf archive.tar directory/

# Create compressed tar archive
tar -czvf archive.tar.gz directory/

# Create zip archive
zip -r archive.zip directory/

# Extract tar archive
tar -xvf archive.tar

# Extract compressed tar archive
tar -xzvf archive.tar.gz

# Extract zip archive
unzip archive.zip

# List archive contents without extracting
tar -tvf archive.tar.gz
zip -l archive.zip

# Compare two files
diff file1.txt file2.txt

# Side-by-side comparison
diff -y file1.txt file2.txt

# Compare directories
diff -r directory1/ directory2/

# Create patch file
diff -u original.txt modified.txt > changes.patch

# Apply patch
patch original.txt < changes.patch

# Generate MD5 checksum
md5sum file.txt

# Generate SHA256 checksum
sha256sum file.txt

# Verify checksums
md5sum -c checksums.md5
sha256sum -c checksums.sha256

# Compare two files by checksum
md5sum file1.txt file2.txt

# Create symbolic link
ln -s /path/to/original /path/to/link

# Create symbolic link in current directory
ln -s /etc/hosts hosts_link

# Link to directory
ln -s ~/Documents/projects projects_link

# Create hard link
ln /path/to/original /path/to/hardlink

# Show file link count
ls -l filename

# Create convenient shortcuts
ln -s ~/Documents/important_project ~/Desktop/project_shortcut
ln -s /var/log/nginx/access.log ~/logs/nginx_access

# Link configuration files
ln -s ~/.config/app/config.conf ~/project/config.conf

# Create backup-friendly links
ln important_file.txt important_file_backup.txt

# Install inotify-tools (Ubuntu/Debian)
sudo apt install inotify-tools

# Watch for file changes
inotifywait -m ~/Documents/

# Watch specific events
inotifywait -m -e modify,create,delete ~/project/

# Recursive monitoring
inotifywait -r -m ~/project/

# Follow file changes in real-time
tail -f /var/log/syslog

# Follow multiple files
tail -f /var/log/syslog /var/log/auth.log

# Follow with line numbers
tail -n +1 -f file.txt

# View detailed permissions
ls -la filename

# Change permissions
chmod 755 script.sh        # rwxr-xr-x
chmod u+x script.sh        # Add execute for user
chmod g-w file.txt         # Remove write for group
chmod a+r file.txt         # Add read for all

# Change ownership
chown user:group file.txt
chown user file.txt
chgrp group file.txt

# Create a development project structure
mkdir -p ~/projects/web-app/{src,tests,docs,config,logs}
cd ~/projects/web-app

# Create sample files
touch src/{index.html,app.js,style.css}
touch tests/{test_app.js,test_utils.js}
touch docs/{README.md,API.md}
touch config/{dev.conf,prod.conf}

# Verify structure
tree . # or ls -la if tree isn't installed

# Create test files
mkdir ~/file_exercise
cd ~/file_exercise

# Create various file types
touch document{1..5}.txt
touch image{1..3}.{jpg,png}
touch script{1..2}.{py,sh}
touch config{1..2}.{conf,cfg}

# Practice searches
find . -name "*.txt"
find . -name "image*"
find . -type f -name "*.py" -o -name "*.sh"
ls *.{jpg,png}

# Create backup directory
mkdir ~/backup

# Copy all text files
cp *.txt ~/backup/

# Rename all .cfg files to .config
for file in *.cfg; do
    mv "$file" "${file%.cfg}.config"
done

# Or using rename command (if available)
rename 's/\.cfg$/.config/' *.cfg

#!/bin/bash
# backup_important.sh

BACKUP_DIR="$HOME/backups/$(date +%Y-%m-%d)"
mkdir -p "$BACKUP_DIR"

# Backup important directories
cp -r ~/Documents "$BACKUP_DIR/"
cp -r ~/projects "$BACKUP_DIR/"
cp ~/.bashrc "$BACKUP_DIR/"

echo "Backup completed to $BACKUP_DIR"

#!/bin/bash
# cleanup_temp.sh

# Remove temporary files older than 7 days
find /tmp -name "*.tmp" -mtime +7 -delete
find ~/Downloads -name "*.tmp" -mtime +7 -delete

# Clean up empty directories
find ~/projects -type d -empty -delete

echo "Cleanup completed"

#!/bin/bash
# organize_downloads.sh

DOWNLOADS="$HOME/Downloads"
cd "$DOWNLOADS"

# Organize by file type
mkdir -p Images Documents Archives Scripts

mv *.{jpg,jpeg,png,gif,bmp} Images/ 2>/dev/null
mv *.{pdf,doc,docx,txt,odt} Documents/ 2>/dev/null
mv *.{zip,tar,gz,rar,7z} Archives/ 2>/dev/null
mv *.{sh,py,pl,rb} Scripts/ 2>/dev/null

echo "Downloads organized"

# Check file permissions
ls -la problematic_file

# Fix common permission issues
chmod 644 regular_file      # Read/write for owner, read for others
chmod 755 executable_file   # Execute permissions for all
chmod 600 private_file      # Read/write for owner only

# Check disk usage
df -h

# Find large files
find / -size +100M 2>/dev/null | head -20

# Check directory sizes
du -sh */ | sort -hr

# Clean package cache (Ubuntu/Debian)
sudo apt clean

# Attempt to recover deleted files (install testdisk)
sudo apt install testdisk
sudo photorec

# Check for file fragments
sudo grep -a -B 25 -A 25 'unique_text_from_file' /dev/sda1

# Wildcards
*           # Match any characters
?           # Match single character
[abc]       # Match any of a, b, c
[0-9]       # Match any digit
{jpg,png}   # Match jpg or png

# Find Operations
find . -name "pattern"      # Find by name
find . -type f              # Find files
find . -size +10M           # Find large files
find . -mtime -7            # Modified in last 7 days
find . -exec command {} \;  # Execute on results

# Bulk Operations
cp *.txt backup/           # Copy all txt files
mv *.log archives/         # Move all log files
rm *.tmp                   # Remove temp files
chmod +x *.sh              # Make scripts executable

# Archives
tar -czvf archive.tar.gz directory/  # Create archive
tar -xzvf archive.tar.gz             # Extract archive
zip -r archive.zip directory/        # Create zip
unzip archive.zip                    # Extract zip