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info.md

File metadata and controls

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Info Command

The info command displays detailed information about an APACK archive's format, configuration, and content statistics.

Syntax

apack info [OPTIONS] <archive>
apack i [OPTIONS] <archive>

Arguments:

  • <archive> - Path to the archive file to inspect

Options

Option Description Default
--json Output in JSON format false

Information Sections

File Section

Basic file information:

Field Description
Path Full path to the archive file
Size Archive file size on disk

Format Section

Archive format details:

Field Description
Version Format version (major.minor.patch)
Compat Level Minimum version required to read
Mode Container or Stream
Chunk Size Size of data chunks
Checksum Checksum algorithm used

Flags Section

Archive capability flags:

Field Description
Random Access Table of contents present
Encrypted Archive-level encryption enabled
Compressed Archive-level compression enabled

Content Section

Entry statistics:

Field Description
Entries Total number of entries
Original Size Total uncompressed size
Stored Size Total size in archive
Compression Ratio Stored/Original percentage
Compressed Entries Count with compression
Encrypted Entries Count with encryption
ECC Entries Count with error correction

Examples

Basic Information

apack info archive.apack

Output:

APACK Archive Information
========================================

File:
  Path: archive.apack
  Size: 3.8 MB

Format:
  Version: 1.0.0
  Compat Level: 1
  Mode: Container
  Chunk Size: 256 KB
  Checksum: XXH3-64

Flags:
  Random Access: Yes
  Encrypted: No
  Compressed: Yes

Content:
  Entries: 42
  Original Size: 15.2 MB
  Stored Size: 3.8 MB
  Compression Ratio: 25.0%
  Compressed Entries: 42
  Encrypted Entries: 0
  ECC Entries: 0

JSON Output

apack info --json archive.apack

Output:

{
  "file": "archive.apack",
  "fileSize": 3984560,
  "format": {
    "versionMajor": 1,
    "versionMinor": 0,
    "versionPatch": 0,
    "compatLevel": 1,
    "streamMode": false,
    "chunkSize": 262144,
    "checksumAlgorithm": 2,
    "randomAccess": true,
    "encrypted": false,
    "compressed": true
  },
  "content": {
    "entryCount": 42,
    "originalSize": 15938560,
    "storedSize": 3984560,
    "compressedEntries": 42,
    "encryptedEntries": 0,
    "eccEntries": 0
  }
}

Version Information

Version Fields

Field Description
Major Breaking changes
Minor New features (backward compatible)
Patch Bug fixes
Compat Level Minimum reader version required

Compatibility

Archive Version: 1.2.3
Compat Level: 1

Readers with version >= 1.0.0 can read this archive

Mode Types

Container Mode

Standard archive with table of contents:

  • Random access to entries by name
  • Full metadata available
  • Suitable for most use cases

Stream Mode

Optimized for streaming:

  • No table of contents
  • Sequential reading only
  • Smaller footer
  • Suitable for pipes and streaming

Checksum Algorithms

ID Name Description
1 CRC32 Standard CRC-32
2 XXH3-64 Fast 64-bit hash (default)
3 XXH3-128 Fast 128-bit hash

Scripting Examples

Extract Specific Information

# Get version
apack info --json archive.apack | jq '.format.versionMajor'

# Get entry count
apack info --json archive.apack | jq '.content.entryCount'

# Get compression ratio
apack info --json archive.apack | jq '(.content.storedSize / .content.originalSize * 100 | floor)'

# Check if encrypted
apack info --json archive.apack | jq '.format.encrypted'

Compare Archives

# Compare entry counts
echo "Archive 1: $(apack info --json a1.apack | jq '.content.entryCount') entries"
echo "Archive 2: $(apack info --json a2.apack | jq '.content.entryCount') entries"

Validation Scripts

#!/bin/bash
# Check archive properties

archive=$1
info=$(apack info --json "$archive")

if echo "$info" | jq -e '.format.encrypted' > /dev/null; then
    echo "Archive is encrypted"
else
    echo "Archive is NOT encrypted"
fi

entries=$(echo "$info" | jq '.content.entryCount')
if [ "$entries" -eq 0 ]; then
    echo "Warning: Archive is empty"
fi

Report Generation

#!/bin/bash
# Generate archive report

for archive in *.apack; do
    info=$(apack info --json "$archive")
    entries=$(echo "$info" | jq '.content.entryCount')
    size=$(echo "$info" | jq '.fileSize')
    echo "$archive: $entries entries, $size bytes"
done

Use Cases

Pre-Extraction Check

# Check if you need a password
apack info archive.apack | grep "Encrypted:"

# Check available space needed
apack info archive.apack | grep "Original Size:"

Archive Comparison

# Quick summary comparison
echo "=== Original ==="
apack info original.apack | grep -E "(Entries|Original Size|Stored Size)"

echo "=== Updated ==="
apack info updated.apack | grep -E "(Entries|Original Size|Stored Size)"

Compression Analysis

# Check compression effectiveness
apack info archive.apack | grep "Compression Ratio:"

# Find if all entries are compressed
compressed=$(apack info --json archive.apack | jq '.content.compressedEntries')
total=$(apack info --json archive.apack | jq '.content.entryCount')
echo "$compressed of $total entries are compressed"

Format Version Check

# Check compatibility before processing
version=$(apack info --json archive.apack | jq -r '.format.versionMajor')
if [ "$version" -gt 1 ]; then
    echo "Warning: Archive uses newer format version"
fi

Error Handling

Common Errors

Error Cause Solution
"Archive not found" File doesn't exist Check the path
Format error Invalid archive Verify with apack verify

Exit Codes

Code Meaning
0 Success
1 Error (file not found, format error)

Next: Verify Command | Previous: List Command