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Command documentation sourced from the linux-command project This comprehensive command reference is part of the linux-command documentation project.

isoformat - ISO 9660 Filesystem Creation and Formatting Tool

The isoformat command is a comprehensive tool for creating ISO 9660 filesystem images, which are standardized optical disc formats used for CD-ROM, DVD, and Blu-ray media. This tool supports various filesystem extensions including Joliet for Unicode filenames, Rock Ridge for Unix-style permissions, and HFS for Macintosh compatibility. It's commonly used for creating bootable installation media, software distribution images, data backups, and archival storage of directory structures.

Basic Syntax​

isoformat [OPTIONS] -o output_image.iso source_directory
isoformat [OPTIONS] source_files... output_image.iso

Common Command Modes​

  • Default Mode - Create basic ISO 9660 filesystem
  • Joliet Extension - Enable long Unicode filenames
  • Rock Ridge Extension - Preserve Unix permissions and attributes
  • HFS Hybrid - Create hybrid ISO/HFS filesystem
  • Bootable Mode - Create El Torito bootable images

Core Options​

Output Control​

  • -o FILE - Specify output ISO image filename
  • -V VOLID - Set volume ID (32 characters max)
  • -v - Verbose output (show progress)
  • -quiet - Suppress non-error messages
  • -print-size - Print estimated filesystem size

Filesystem Options​

  • -J - Enable Joliet extensions (Unicode support)
  • -R or -r - Enable Rock Ridge extensions
  • -hfs - Create HFS hybrid filesystem
  • -UDF - Enable UDF filesystem support
  • -allow-lowercase - Allow lowercase filenames
  • -allow-multidot - Allow multiple dots in filenames

File Selection​

  • -graft-points - Enable graft points for directory mapping
  • -path-list FILE - Read source paths from file
  • -exclude-list FILE - Exclude files listed in file
  • -m GLOB - Exclude files matching glob pattern
  • -x DIR - Exclude directory from image

Usage Examples​

Basic ISO Creation​

Simple Directory ISO​

# Create basic ISO from directory
isoformat -o data.iso /home/user/documents/

# Create ISO with custom volume name
isoformat -V "MyData" -o backup.iso /backup/files/

# Create ISO with specific files
isoformat -o project.iso file1.txt file2.pdf program.exe

Verbose Output and Progress​

# Create ISO with detailed progress
isoformat -v -o large.iso /huge/directory/

# Show estimated size before creation
isoformat -print-size -o test.iso /source/

Extended Filesystem Features​

Joliet Extensions (Unicode Support)​

# Create ISO with Unicode filename support
isoformat -J -o unicode.iso /multilingual/files/

# Combine Joliet with Rock Ridge
isoformat -J -r -o extended.iso /source/directory/

# Create ISO for Windows compatibility
isoformat -J -allow-lowercase -allow-multidot -o windows.iso /files/

Rock Ridge Extensions (Unix Features)​

# Preserve Unix permissions and symbolic links
isoformat -r -o unix_backup.iso /home/user/

# Create ISO with ownership preserved
isoformat -r -o system.iso /etc /var /home

# Use Rock Ridge with specific UID/GID
isoformat -r -uid 1000 -gid 1000 -o user_backup.iso /home/user/

HFS Hybrid Creation​

# Create Mac/PC hybrid ISO
isoformat -hfs -o hybrid.iso /shared/files/

# Create ISO with HFS and Joliet
isoformat -hfs -J -o universal.iso /cross_platform/

Bootable ISO Creation​

El Torito Bootable Images​

# Create bootable ISO with boot image
isoformat -b boot.img -o bootable.iso /installation/files/

# Create bootable ISO with boot catalog
isoformat -b boot.img -c boot.cat -o system.iso /boot/directory/

# Create no-emulation bootable ISO
isoformat -b boot.bin -no-emul-boot -boot-load-size 4 -o installer.iso /install/files/

# Create bootable ISO with boot info table
isoformat -b isolinux.bin -c boot.cat -no-emul-boot -boot-load-size 4 -boot-info-table -o live.iso /live/files/

UEFI Boot Support​

# Create dual BIOS/UEFI bootable ISO
isoformat -b bios_boot.img -eltorito-alt-boot -e efi_boot.img -no-emul-boot -o dual_boot.iso /system/

# Create UEFI-only bootable ISO
isoformat -e efi_boot.img -no-emul-boot -o uefi.iso /uefi/files/

Advanced File Selection and Filtering​

Graft Points and Directory Mapping​

# Map directories to different locations in ISO
isoformat -o mapped.iso /src/dir1=/target/dir1 /src/dir2=/target/dir2

# Create custom directory structure
isoformat -graft-points -o custom.iso \
    /documents=/home/user/docs \
    /photos=/media/pictures \
    /software=/usr/local/bin/tools

File Exclusion and Inclusion​

# Exclude temporary files
isoformat -o clean.iso /source/ -x "*.tmp" -x "*.log" -x "cache/"

# Exclude directories
isoformat -o filtered.iso /project/ -x ".git" -x "node_modules" -x "build/"

# Use exclusion list file
echo "*.bak
*.temp
cache/
.git/" > exclude.txt
isoformat -exclude-list exclude.txt -o archive.iso /project/

# Include specific file types only
find /source -name "*.pdf" -o -name "*.doc" | isoformat -path-list - -o documents.iso

File Attribute Control​

# Hide files from Joliet but keep in Rock Ridge
isoformat -J -r -hide-joliet *.iso -o mixed.iso /source/

# Set file permissions in ISO
isoformat -r -chmod 755 /bin/* -o exec.iso /programs/

# Set file timestamps
isoformat -date "20240101000000" -o dated.iso /archive/

Specialized ISO Types​

Software Distribution ISO​

# Create software distribution ISO
isoformat -J -r -V "MySoftware v1.0" -o software_v1.0.iso \
    /build/release/ \
    -graft-points \
    /README=README.md \
    /LICENSE=LICENSE.txt \
    /docs=/documentation/ \
    /bin=/build/binaries/

# Create portable application ISO
isoformat -J -r -o portable_app.iso \
    -graft-points \
    /app=/application/ \
    /data=/config/ \
    /autorun.inf=autorun.inf

System Backup ISO​

# Create system backup with permissions
isoformat -r -uid 0 -gid 0 -o system_backup.iso \
    /etc /var/log /home /usr/local

# Create incremental backup (compare with previous)
isoformat -r -o backup_$(date +%Y%m%d).iso /home/user/

# Create compressed backup structure
tar -czf - /important/data/ | isoformat -o backup.iso -gzip -

Multimedia Archive ISO​

# Create photo archive ISO
isoformat -J -r -V "Photo Archive 2024" -o photos_2024.iso \
    /media/pictures/2024/

# Create music collection ISO
isoformat -J -V "Music Collection" -o music.iso \
    /media/music/ -x "*.m3u" -x "thumbs.db"

# Create video backup ISO with UDF
isoformat -J -UDF -V "Video Archive" -o videos.iso /media/videos/

Practical Examples​

System Administration​

Installation Media Creation​

# Create Linux distribution ISO
isoformat -J -r -V "LinuxCustom" -o linux_custom.iso \
    /path/to/distro/files/ \
    -b isolinux.bin -c boot.cat \
    -no-emul-boot -boot-load-size 4 -boot-info-table

# Create Windows PE ISO
isoformat -J -V "WinPE" -o winpe.iso \
    /winpe/sources/ \
    -b etfsboot.com -no-emul-boot

# Create rescue disk ISO
isoformat -J -r -V "RescueDisk" -o rescue.iso \
    /rescue/files/ \
    -b memdisk -c boot.cat \
    -no-emul-boot -boot-load-size 4

Network Boot Images​

# Create PXE boot ISO
isoformat -J -r -o pxe_boot.iso /tftpboot/ \
    -b pxelinux.0 -c boot.cat \
    -no-emul-boot -boot-load-size 4

# Create diskless client ISO
isoformat -J -r -V "DisklessClient" -o diskless.iso \
    /netboot/client/ \
    -b kernel -c boot.cat \
    -no-emul-boot -boot-load-size 4

Development Workflow​

Application Distribution​

# Create cross-platform application ISO
isoformat -J -r -hfs -o app_crossplatform.iso \
    -graft-points \
    /windows=/build/windows/ \
    /linux=/build/linux/ \
    /macos=/build/macos/ \
    /docs=/documentation/ \
    /examples=/sample_code/

# Create source code archive ISO
isoformat -J -r -V "SourceCode_v2.1" -o source_v2.1.iso \
    /src/ \
    -exclude-list exclude_dev.txt \
    -graft-points \
    /README=README.md \
    /CHANGELOG=CHANGELOG.md \
    /LICENSE=LICENSE.txt

Documentation Distribution​

# Create technical documentation ISO
isoformat -J -r -V "TechDocs" -o techdocs.iso \
    /documentation/ \
    -graft-points \
    /index.html=index.html \
    /search=search.html \
    /help=/help_files/

# Create training materials ISO
isoformat -J -V "TrainingCourse" -o training.iso \
    -graft-points \
    /slides=/presentation_slides/ \
    /exercises=/lab_exercises/ \
    /resources=/additional_resources/ \
    /README=training_guide.txt

Advanced Usage​

Performance Optimization​

Memory and Buffer Management​

# Use specific buffer size for large files
isoformat -b 32M -o large.iso /huge/files/

# Optimize for many small files
isoformat -sort sort_file.txt -o optimized.iso /many_files/

# Create ISO with streaming
tar -cf - /source/ | isoformat -o streamed.iso -

Parallel Processing​

# Create multiple ISOs in parallel
for dir in /data/*/; do
    (isoformat -o "$(basename "$dir").iso" "$dir" &) &
done
wait

# Create ISO with background processing
isoformat -o background.iso /source/ &
progress_pid=$!
# Monitor progress here
wait $progress_pid

Customization and Special Features​

Custom File Ordering​

# Sort files for optimal access
echo "/boot/kernel
/boot/initrd
/important/config
/data" > sort_order.txt
isoformat -sort sort_order.txt -o optimized.iso /system/

Volume Label and Metadata​

# Create ISO with extended metadata
isoformat -V "Archive_2024_Q1" \
    -publisher "MyCompany" \
    -preparer "SystemAdmin" \
    -appid "BackupSystem v2.0" \
    -sysid "LINUX" \
    -o metadata.iso /backup/

# Create ISO with abstract and bibliographic files
isoformat -abstract abstract.txt -biblio biblio.txt -o documented.iso /data/

Custom Volume Attributes​

# Set creation date and modification date
isoformat -date "20240101000000" -o dated.iso /archive/

# Create ISO with specific file system parameters
isoformat -iso-level 4 -o modern.iso /new_files/

Integration and Automation​

Shell Scripts​

Automated Backup Script​

#!/bin/bash
# Automated ISO backup with rotation

BACKUP_DIR="/backups"
SOURCE_DIR="/important/data"
MAX_BACKUPS=7
DATE=$(date +%Y%m%d_%H%M%S)

# Create ISO backup
isoformat -J -r -V "Backup_$DATE" -o "$BACKUP_DIR/backup_$DATE.iso" "$SOURCE_DIR"

# Verify ISO creation
if [ $? -eq 0 ]; then
    echo "Backup created successfully: backup_$DATE.iso"

    # Clean up old backups
    cd "$BACKUP_DIR"
    ls -t backup_*.iso | tail -n +$((MAX_BACKUPS + 1)) | xargs -r rm
    echo "Old backups cleaned up"
else
    echo "Backup creation failed!"
    exit 1
fi

ISO Creation Pipeline​

#!/bin/bash
# Pipeline for creating distribution ISO

SOURCE="/build/output"
OUTPUT="/distrib/app.iso"
TEMP_SORT="/tmp/sort_list.txt"

# Create file sorting list
echo "/application/" > "$TEMP_SORT"
echo "/data/" >> "$TEMP_SORT"
echo "/documentation/" >> "$TEMP_SORT"

# Create ISO with optimizations
isoformat -J -r \
    -V "MyApplication_v2.0" \
    -sort "$TEMP_SORT" \
    -b boot.img -c boot.cat \
    -no-emul-boot -boot-load-size 4 \
    -o "$OUTPUT" "$SOURCE"

# Verify and create checksum
if [ -f "$OUTPUT" ]; then
    sha256sum "$OUTPUT" > "${OUTPUT}.sha256"
    echo "ISO created and verified: $OUTPUT"
    ls -lh "$OUTPUT"
else
    echo "ISO creation failed!"
    exit 1
fi

rm "$TEMP_SORT"

Makefile Integration​

# Makefile for ISO creation
SOURCE_DIR = ./src
OUTPUT_DIR = ./dist
ISO_NAME = application.iso

.PHONY: iso clean

iso:
	@mkdir -p $(OUTPUT_DIR)
	isoformat -J -r -V "MyApp" -o $(OUTPUT_DIR)/$(ISO_NAME) $(SOURCE_DIR)

clean:
	rm -f $(OUTPUT_DIR)/$(ISO_NAME)

help:
	@echo "Available targets:"
	@echo "  iso   - Create ISO image"
	@echo "  clean - Remove ISO image"

Troubleshooting​

Common Issues​

Filesystem Limitations​

# ISO 9660 Level 1 limitations (8.3 filenames)
isoformat -iso-level 1 -o compatible.iso /old_system/

# ISO 9660 Level 2 (31 character filenames)
isoformat -iso-level 2 -o level2.iso /source/

# ISO 9660 Level 3 (no file size limit)
isoformat -iso-level 3 -o level3.iso /large_files/

Character Encoding Issues​

# Specify input character set
isoformat -input-charset UTF-8 -J -o unicode.iso /unicode_files/

# Specify output character set
isoformat -output-charset UTF-8 -J -o output.iso /source/

# Use legacy character sets for compatibility
isoformat -input-charset ISO-8859-1 -J -o legacy.iso /old_files/

Boot Image Issues​

# Create bootable ISO with proper boot image size
isoformat -b boot.img -boot-load-size 4 -no-emul-boot -o boot.iso /files/

# Fix boot image not found
isoformat -b isolinux.bin -c boot.cat -no-emul-boot -boot-info-table -o fixed.iso /files/

# Create BIOS-only bootable ISO
isoformat -b bios.img -no-emul-boot -o bios_only.iso /bios_files/

Large File and Directory Issues​

# Handle files larger than 2GB
isoformat -iso-level 3 -o large_files.iso /huge_files/

# Handle deep directory structures
isoformat -r -deep-iso -o deep_structure.iso /very/deep/tree/

# Optimize for many small files
isoformat -sort small_files.txt -o many_small.iso /small_files/

Verification and Testing​

ISO Image Verification​

# Check ISO integrity
isoinfo -d -i image.iso

# List ISO contents
isoinfo -l -i image.iso

# Extract files from ISO for verification
isoinfo -x "/path/to/file" -i image.iso > extracted_file

# Mount ISO for testing
mkdir -p /tmp/iso_test
mount -o loop image.iso /tmp/iso_test
ls -la /tmp/iso_test/
umount /tmp/iso_test

Boot Testing​

# Test bootable ISO with QEMU
qemu-system-x86_64 -cdrom bootable.iso

# Test UEFI boot
qemu-system-x86_64 -bios /usr/share/ovmf/OVMF.fd -cdrom uefi.iso
  • mkisofs - Original ISO 9660 filesystem creator
  • genisoimage - Enhanced ISO creation tool
  • xorriso - ISO manipulation and burning tool
  • xorrisofs - ISO 9660 Rock Ridge frontend
  • isoinfo - ISO 9660 image information utility
  • cdrecord - CD/DVD recording tool
  • wodim - Optical media burning utility
  • growisofs - DVD/Blu-ray recording tool

Best Practices​

  1. Always use Joliet extensions (-J) for cross-platform compatibility
  2. Use Rock Ridge extensions (-r) when preserving Unix permissions
  3. Set appropriate volume labels (-V) for easy identification
  4. Test bootable ISOs in virtual machines before burning
  5. Verify ISO integrity after creation using isoinfo
  6. Use exclusion patterns to avoid including unnecessary files
  7. Sort files for optimal access performance
  8. Consider file size limits for target platform compatibility
  9. Use graft points for custom directory structures
  10. Create checksums of ISO files for integrity verification

Performance Tips​

  1. Level 3 ISO provides best performance for large files
  2. File sorting improves access time for frequently used files
  3. Buffer size tuning helps with large file operations
  4. Parallel processing for multiple ISO creation
  5. Exclude unnecessary files to reduce creation time
  6. Use appropriate filesystem extensions for your use case
  7. Memory allocation affects performance with many small files
  8. Verbose output helps identify bottlenecks in creation process

The isoformat command provides comprehensive ISO 9660 filesystem creation capabilities with extensive support for modern filesystem extensions, bootable images, and cross-platform compatibility. Its rich feature set makes it an essential tool for creating installation media, software distributions, system backups, and archival storage solutions.

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