RPM and DEB Versioning

RPM (4.7.1) version format

Information taken from:

• the RPM header definition
• the handlePreambleTag routine defined in build/parsePreamble.c file

The RPM version is stored as 3 separated TAGS in the RPM binary file header:

epoch

• Deprecated
• A single (generally small) unsigned integer
• Zero if omitted
• Used for packager versioning mistakes, should not be used regularly

version

• Mandatory
• Characters NOT allowed: - / ~ .. (hyphen, slash, tilde, double dot)
• Spaces not allowed

release

• Optional
• Characters NOT allowed: - / ~ .. (hyphen, slash, tilde, double dot)
• Spaces not allowed

RPM string representation of the version is:

version[-release]

RPM (4.7.1) version comparison algorithm

Information taken form:

• the rpmVersionCompare routine defined in lib/psm.c file
• the rpmvercmp routine defined in lib/rpmvercmp.c file

The comparison order is:

• Numeric comparison of the epoch
• Alphanumeric comparison of the version
• Alphanumeric comparison of the revision

Alphanumeric comparison:

1) The 2 strings are divided in blocks:

• contiguous numbers
• contiguous letters

all not-alphanumeric characters are ignored

Example:

• 1.25a!0056.ABC_36c
• 1.b.34.a6+ABC(22)fg

become:

2) The comparison is done block by block left to right

• number block <=> number block (number comparison)
• alpha block <=> alpha block (ASCII comparison)
• number block > alpha block
• any block > no block left

3) At the first inequality the algorithm exits.

RPM (4.7.1) version comparison examples

INTUITIVE:

• 1.2.3-5 > 1.2.3-6
• 1.2.3-b > 1.2.3-a
• 1.2.3 > 1.2

NON-INTUITIVE:

• 1-VDT_1.2_5 > 1-VDT_1.2.4_6
• 1-VDT_1.0 > 1-VDT_1.a
• 1-VDT_1_a > 1-VDT_1_A
• 1.2.3-1 = 1_2_3-1 = 1_2+3-1 = 1+2+3-1 = 1@2^3-1

DEB version format (dpkg 1.14.25)

Information taken form:

• the parseversion routine defined in lib/parsehelp.c file
• Debian documentation: http://www.debian.org/doc/debian-policy/ch-controlfields.html
• control file inside control.tar.gz inside any DEB binary

The version of a DEB package is stored as a string of the following format:

• [epoch:]version[-revision]

With:

epoch

• a single (generally small) unsigned integer
• Zero if omitted
• Used for packager versioning mistakes, should not be used regularly

version

• Mandatory
• Allowed characters: A-Za-z0-9 and . + - : ~ (dot plus hyphen colon tilde)
• If one or more : (colon) are used, the first one is used as epoch-version delimiter
• If one or more - (hyphen) are used, the last one is used as version-revision delimiter
• Should start with a digit (not enforced)
• Must contain at least one digit

release

• Optional
• Allowed characters: A-Za-z0-9 and . + ~ (dot plus tilde)
• Should restart from 1 when version changes (not enforced)
• If present, must contain at least one digit

DEB version comparison algorithm (dpkg 1.14.25)

Information taken form:

• the versioncompare and verrevcmp routines defined in lib/vercmp.c file
• Debian documentation: http://www.debian.org/doc/debian-policy/ch-controlfields.html

The comparison order is:

• Numeric comparison of the epoch
• Alphanumeric comparison of the version
• Alphanumeric comparison of the revision

The algorithm returns at the first difference found.

The Alphanumeric comparison has the following rules:

• character to character comparison left to right
• if both characters are digit -> consecutive digits are grouped -> numerical comparison
• if one or both is not a digit -> using ALPHA ORDER

ALPHA ORDER: "~" < "" = 0-9 < A-Z < a-z < + (plus) < - (hyphen) < . (dot) < : (column)

DEB version comparison examples (dpkg 1.14.25)

INTUITIVE:

• 1.2.3-5 > 1.2.3-6
• 1.2.3-b > 1.2.3-a
• 1.2.3 > 1.2

NON-INTUITIVE:

• 1.2.3 > 1.2.3~5
• 1-1.a > 1-1.1
• 1-1_a > 1-1_A
• 1.2: > 1.2a:

Differences in format and comparison algorithms

-- LorenzoDini - 08-Oct-2009