unzip

Overview

The unzip command extracts files from ZIP archives. It’s the counterpart to zip and provides various options for extraction, testing, and listing archive contents.

Syntax

unzip [options] archive.zip [file(s)] [-x excluded_files] [-d extract_dir]

Common Options

Option Description
-l List archive contents
-t Test archive integrity
-d dir Extract to directory
-j Junk paths (flatten directory structure)
-o Overwrite files without prompting
-n Never overwrite existing files
-u Update files (extract if newer)
-f Freshen existing files only
-v Verbose listing
-q Quiet mode
-x files Exclude specified files
-p Extract to pipe (stdout)

Key Use Cases

  1. Extract ZIP archives
  2. List archive contents
  3. Test archive integrity
  4. Selective file extraction
  5. Archive maintenance

Examples with Explanations

Example 1: Basic Extraction

unzip archive.zip

Extracts all files to current directory

Example 2: Extract to Directory

unzip archive.zip -d /target/directory/

Extracts files to specified directory

Example 3: List Contents

unzip -l archive.zip

Lists files in archive without extracting

Example 4: Test Archive

unzip -t archive.zip

Tests archive integrity without extracting

Selective Extraction

  1. Extract specific files:

    unzip archive.zip file1.txt file2.txt

  2. Extract by pattern:

    unzip archive.zip "*.txt"

  3. Exclude files:

    unzip archive.zip -x "*.tmp" "temp/*"

Advanced Options

Option Description
-C Match filenames case-insensitively
-L Convert filenames to lowercase
-a Auto-convert text files
-b Treat all files as binary
-M Pipe through more
-z Display archive comment
-Z Display zipinfo-style listing

Common Usage Patterns

  1. Safe extraction:

    unzip -n archive.zip

  2. Overwrite all:

    unzip -o archive.zip

  3. Flatten directory structure:

    unzip -j archive.zip

Archive Information

  1. Detailed listing:

    unzip -v archive.zip

  2. Archive comment:

    unzip -z archive.zip

  3. Technical info:

    unzip -Z archive.zip

Performance Analysis

  • Fast extraction for most archives
  • Memory usage depends on compression method
  • Good for moderate-sized archives
  • Handles password-protected archives
  • Efficient selective extraction

Best Practices

  1. Test archives before extraction
  2. Use appropriate extraction directory
  3. Check available disk space
  4. Verify file permissions after extraction
  5. Handle filename conflicts appropriately

Security Considerations

  1. Zip bomb protection:

    unzip -l archive.zip | awk '{sum+=$1} END {if(sum>1000000000) print "Large archive warning"}'

  2. Path traversal protection:

    unzip -j archive.zip  # Flatten paths

  3. Verify archive source

  4. Check extracted file permissions

  5. Scan for malicious content

Password-Protected Archives

  1. Extract with password:

    unzip -P password archive.zip

  2. Prompt for password:

    unzip archive.zip
# Will prompt if password needed

Integration Examples

  1. Automated extraction:

    for archive in *.zip; do
    unzip -q "$archive" -d "${archive%.zip}"
done

  2. Backup restoration:

    unzip -o backup.zip -d /restore/location/

  3. Selective processing:

    unzip -p archive.zip "*.txt" | grep "pattern"

Error Handling

  1. Check extraction success:

    if unzip -t archive.zip > /dev/null 2>&1; then
    unzip archive.zip
else
    echo "Archive is corrupted"
fi

  2. Handle missing files:

    unzip archive.zip 2>/dev/null || echo "Extraction failed"

Scripting Applications

  1. Batch extraction:

    #!/bin/bash
for zip_file in *.zip; do
    echo "Extracting $zip_file"
    unzip -q "$zip_file" -d "${zip_file%.zip}"
done

  2. Archive validation:

    validate_archive() {
    local archive="$1"
    if unzip -t "$archive" >/dev/null 2>&1; then
        echo "Valid: $archive"
        return 0
    else
        echo "Invalid: $archive"
        return 1
    fi
}

Troubleshooting

  1. Corrupted archives
  2. Insufficient disk space
  3. Permission issues
  4. Filename encoding problems
  5. Path length limitations

Output Formats

  1. Simple list:

    unzip -l archive.zip | tail -n +4 | head -n -2

  2. Size information:

    unzip -l archive.zip | grep -E "^\s*[0-9]"

  3. Date sorting:

    unzip -v archive.zip | sort -k7,8