See also: File System Structure
Linux identifies file type by content (magic bytes), not extension. The file command reveals actual type:
file document.pdf # PDF document, version 1.6
file image.jpg # JPEG image data
file script.sh # Bourne-Again shell script
file binary # ELF 64-bit LSB executable
file archive.tar.gz # gzip compressed data| Category | Linux Extensions | Windows Extensions |
|---|---|---|
| Text | .txt, .md, .csv, .log |
.txt, .log, .csv |
| Script | .sh, .bash, .py, .pl |
.bat, .cmd, .ps1 |
| Config | .conf, .yaml, .toml, .ini |
.ini, .cfg, .xml, .reg |
| Executable | (no ext required) | .exe, .msi, .dll |
| Archive | .tar, .gz, .zip, .bz2, .xz |
.zip, .7z, .rar |
| Image | .jpg, .png, .gif, .svg |
same |
| Document | .pdf, .odt, .docx |
.docx, .xlsx, .pdf |
- Reduce disk space usage
- Faster file transfers
- Bundle many files into one (archiving)
tar is primarily for archiving (bundling); compression is added via flags.
# Create archive
tar -cvf archive.tar files/ # Create, verbose, file
tar -czvf archive.tar.gz files/ # + gzip compression
tar -cjvf archive.tar.bz2 files/ # + bzip2 compression
tar -cJvf archive.tar.xz files/ # + xz compression
# Extract archive
tar -xvf archive.tar # Extract, verbose
tar -xzvf archive.tar.gz # Extract gzip
tar -xjvf archive.tar.bz2 # Extract bzip2
tar -xJvf archive.tar.xz # Extract xz
tar -xvf archive.tar -C /dest/ # Extract to specific directory
# List contents (don't extract)
tar -tvf archive.tar
tar -tzvf archive.tar.gz
# Extract specific file
tar -xvf archive.tar file.txt
# Flags explained:
# c = create x = extract t = list
# v = verbose f = file (must specify filename)
# z = gzip j = bzip2 J = xzgzip file.txt # Compress → file.txt.gz (original deleted)
gzip -k file.txt # Keep original
gzip -d file.txt.gz # Decompress (same as gunzip)
gunzip file.txt.gz # Decompress
gzip -l file.txt.gz # List compression ratio
gzip -9 file.txt # Maximum compression
gzip -1 file.txt # Fastest (least compression)zip archive.zip file1 file2 # Create zip
zip -r archive.zip folder/ # Recursive
zip -e archive.zip file.txt # Encrypt with password
unzip archive.zip # Extract
unzip archive.zip -d /dest/ # Extract to directory
unzip -l archive.zip # List contents
unzip -p archive.zip file.txt # Print file to stdout| Algorithm | Extension | Speed | Ratio | Use Case |
|---|---|---|---|---|
| gzip | .gz |
Fast | Medium | General purpose |
| bzip2 | .bz2 |
Medium | Better | Source tarballs |
| xz | .xz |
Slow | Best | Package distributions |
| lz4 | .lz4 |
Very fast | Low | Real-time compression |
| zstd | .zst |
Fast | Good | Modern alternative |
| zip | .zip |
Fast | Medium | Windows compat |
# By name
find /home -name "*.txt"
find / -iname "readme*" # Case-insensitive
# By type
find . -type f # Files only
find . -type d # Directories only
find . -type l # Symbolic links
# By size
find / -size +500M # Larger than 500MB
find / -size -1k # Smaller than 1KB
find / -size 1024c # Exactly 1024 bytes
# By time (days)
find . -mtime -7 # Modified within 7 days
find . -mtime +30 # Modified more than 30 days ago
find . -atime -1 # Accessed today
find . -newer /etc/hosts # Newer than /etc/hosts
# By permission
find . -perm 644
find . -perm /111 # Any execute bit set
# By owner
find . -user alice
find . -group devs
# Combining conditions
find /var -name "*.log" -mtime +7 -size +100M
# Execute on results
find . -name "*.tmp" -delete # Delete matches
find . -name "*.txt" -exec ls -l {} \; # ls each file
find . -name "*.log" -exec gzip {} \; # Compress eachSee Linux CLI for full reference
grep "error" /var/log/syslog
grep -r "TODO" /home/alice/projects/
grep -rl "password" /etc/ # Filenames only
grep -n "function" *.py # Show line numberslocate filename # Uses pre-built database
locate -i filename # Case-insensitive
sudo updatedb # Update database
locate "*.conf" | grep nginx # Combine with grepproject/
├── README.md
├── .gitignore
├── src/ # Source code
│ ├── main.py
│ └── utils/
├── tests/ # Test files
├── docs/ # Documentation
├── scripts/ # Helper scripts
├── config/ # Configuration files
├── logs/ # Log output (gitignored)
└── data/ # Data files (often gitignored)
# Show directory tree
tree /path # If tree is installed
find . -type d # All directories
ls -R | grep :/ | sed 's/:/\n/;s/[^/]*/ /g' # DIY tree
# Disk usage
du -sh directory/ # Size of directory
du -sh * # Size of each item in current dir
du -sh * | sort -h # Sort by size
df -h # Disk usage per filesystem
# Count files
ls | wc -l # Count files in current dir
find . -type f | wc -l # Count all files recursivelystat file.txt # Full metadata
ls -l file.txt # Basic metadata
file file.txt # File type detection
# Timestamps
touch file.txt # Update all timestamps to now
touch -a file.txt # Update only atime
touch -m file.txt # Update only mtime
touch -t 202401011200 f # Set specific timestamp
# Attributes (Linux extended attributes)
lsattr file.txt # List attributes
chattr +i file.txt # Make immutable (cannot be deleted/modified, even by root)
chattr -i file.txt # Remove immutable
chattr +a file.txt # Append-only# Linux temp directories
/tmp # Cleared on reboot
/var/tmp # Persists across reboots
# Find and clean old temp files
find /tmp -mtime +7 -delete # Delete files older than 7 days
find /var/log -name "*.gz" -mtime +30 -delete # Old compressed logs
# Clean package cache
sudo apt clean # Debian/Ubuntu
sudo pacman -Sc # Arch Linux
# Clear thumbnail cache
rm -rf ~/.cache/thumbnails/
# Windows temp cleanup
del /Q %TEMP%\* # Clear user temp
cleanmgr # Disk cleanup GUI# Generate checksums
md5sum file.txt # MD5 (fast, not secure)
sha1sum file.txt # SHA-1
sha256sum file.txt # SHA-256 (recommended)
sha512sum file.txt # SHA-512 (most secure)
# Verify checksum
sha256sum -c checksums.txt # Check against file
echo "HASH file.txt" | sha256sum -c -
# Generate checksum file for multiple files
sha256sum *.iso > SHA256SUMS
sha256sum -c SHA256SUMS # Verify allWindows (PowerShell):
Get-FileHash file.txt -Algorithm SHA256
Get-FileHash file.txt -Algorithm MD5See Linux CLI →
# Local sync
rsync -av source/ dest/ # Archive + verbose
rsync -av --delete source/ dest/ # Delete extra files in dest
# Remote sync over SSH
rsync -avz source/ user@host:/dest/ # Compress during transfer
rsync -avz user@host:/remote/ local/ # Pull from remote
# Common flags
# -a = archive (recursive, preserve permissions/timestamps)
# -v = verbose
# -z = compress during transfer
# -n = dry run (test without changes)
# -P = show progress + resume partial
# --exclude='*.log'
# --delete = remove files in dest not in sourcescp file.txt user@host:/path/ # Copy to remote
scp user@host:/path/file.txt ./ # Copy from remote
scp -r dir/ user@host:/path/ # Recursive
scp -P 2222 file user@host:/path/ # Custom portSee Cloud & Remote Access → for SSH details
# Search
Get-ChildItem -Recurse -Filter "*.log"
Get-ChildItem -Path C:\ -Include "*.txt" -Recurse
# Compress (built-in zip)
Compress-Archive -Path folder\ -DestinationPath archive.zip
Expand-Archive -Path archive.zip -DestinationPath dest\
# File info
Get-Item file.txt | Select-Object *
(Get-Item file.txt).LastWriteTime
(Get-Item file.txt).Length
# Checksums
Get-FileHash file.txt -Algorithm SHA256- File System Structure ←
- Linux CLI ←
- Windows CLI ←
- User Permissions ←
- Cloud & Remote Access →
- Git Fundamentals → — version-controlled file management