Packages disappear
The old module is unavailable, its native extension no longer builds or its replacement behaves differently.
Perl, Python & shell runtime upgrade and application modernization
Keep the scripts your business depends on working.
Newer interpreters. Working dependencies. The same business results.
Your scripts and applications run on interpreter versions the new operating system no longer ships. We adapt the code, restore the required packages and check the database connections and system commands around them.
Three different problems, one thing in common: the interpreter version is rarely the whole job. The missing pieces are often packages, assumptions nobody wrote down and utilities that behave differently on the new base.
From $99. Scope, target environment and milestone amounts agreed before work begins. A $100 audit is required first and is fully credited toward the service you choose.
Keep the current system running
Adapt and test on a separate copy before switching.
Preserve the business result
Check files, database changes, output and failure behaviour.
Upgrade or change language
Keep Perl or Python, or convert between them where there is a clear reason.
The interpreter starts. The job still fails.
It was more than a script. It was a whole environment.
A nightly import, customer portal or provisioning task can depend on a specific database driver, command-line tool, working directory and user account. Installing a newer interpreter does not reconstruct those dependencies.
The backend changes
The new OS provides different database clients, drivers and authentication defaults. Reconnecting safely can take more work than adapting the script.
Unwritten assumptions break
Command output, locale, paths, permissions and job scheduling change. A job can finish without doing the same work.
Upgrade the runtime. Modernize selected parts. Or change language.
Perl runtime upgrade
Adapt older Perl code, restore CPAN dependencies, rebuild native modules and verify DBI drivers, regular expressions and file handling.
Python runtime upgrade
Move Python 2 code or older Python 3 applications to an agreed target. Update packages, native extensions, imports, text handling and integrations.
Shell & utility compatibility
Check the actual shell and commands: Bash, POSIX sh, awk, sed, grep, find, curl, database clients and other tools the workflow invokes.
Perl → Python
Port the agreed application or standalone modules to Python. Preserve inputs, outputs, database effects and operational behaviour, with replacements for the Perl modules it uses.
Python → Perl
Port the agreed application or modules to Perl where your environment or maintenance team benefits. Map Python packages to appropriate Perl modules and verify the same business results.
Cross-language conversion is a separate scope from an interpreter upgrade. It involves translating behaviour, not simply replacing syntax. Modules can move incrementally through agreed file, command or API interfaces while the rest of the application remains in its existing language.
Interpreter upgrade & compatibility work
From $99
Based on runtime drift, affected code, dependency condition, database access, external utilities and test requirements.
Cross-language conversion & larger modernization
Quoted by agreed modules and acceptance criteria. Database changes, replacement services, framework work and ongoing dependency maintenance are identified separately.
Audit (required)
$100 · credited toward the service you choose
The audit examines the interpreter, packages, database access and system utilities before the plan and price are finalised. Its full cost is credited against the work you go ahead with.
Need to preserve the old environment and move it first? EOL application rescue covers the server environment. This service covers interpreter compatibility, dependencies and application behaviour. Shared work in a combined project is priced once.
Database access & operating-system compatibility
The backend can be the larger part of the upgrade.
The OS that supports your target Perl or Python version may supply different database servers, client libraries and connectors. Even when the application code needs few changes, its database access layer can require rebuilding, replacement or configuration work.
Perl database accessCheck DBI with the actual DBD driver: DBD::mysql, DBD::Pg, DBD::SQLite, DBD::ODBC or another adapter. Validate module builds, client-library linkage, connection options and the target server.
Python database accessCheck the actual driver and ORM: mysqlclient, PyMySQL, psycopg/psycopg2, sqlite3, pyodbc, SQLAlchemy or project-specific adapters. Package availability and API compatibility depend on the chosen versions.
OS & client librariesInventory development headers, native libraries, ODBC drivers, TLS libraries, certificate stores and database tools. Do not assume an old binary package can move unchanged to the new OS.
Connection behaviourVerify credentials, authentication methods, TLS, socket or TCP paths, character sets, timezones, connection pooling, parameter binding and error handling.
Data correctnessCompare queries, transactions, autocommit, affected-row results, NULL handling and numeric/date conversion. An interpreter upgrade does not automatically require a database-engine migration; any engine or schema change is agreed separately.
“Database access works” means the application reads and writes the correct data under the expected permissions and failure conditions—not just that a connection test succeeds.
Language compatibility checkpoints
Major Perl changes to check.
| Checkpoint | What changed | Work to check |
|---|---|---|
| Older Perl 5 installations | CPAN modules, compiled XS extensions, encodings and installation paths form part of the environment. | Inventory and reproduce the dependencies; rebuild native modules for the target interpreter and OS. Official reference → |
| Perl 5.22 | defined(@array) and defined(%hash) become fatal errors; several older reference constructs also fail. | Replace checks according to their intended meaning and test the callers. Official reference → |
| Perl 5.26 | The current directory is removed from default @INC. Regex literal-brace handling tightens. | Use explicit trusted module/configuration paths; review regex patterns and module installation tests. Official reference → |
| Perl 5.28 | Some formerly deprecated unescaped left braces in regex patterns become fatal. | Distinguish literal braces from quantifiers and verify representative matches. Official reference → |
| Across Perl releases | Unicode, regex, warnings, core modules and native interfaces evolve. | Review every intervening perldelta and the modules actually used; Perl 5 compatibility does not guarantee an unchanged environment. Official reference → |
Major Python changes to check.
| Checkpoint | What changed | Work to check |
|---|---|---|
| Python 2 → 3 | print becomes a function; text and bytes separate; division and iteration APIs change. | Adapt syntax and semantics, file encodings, dictionary iteration and dependencies. Official reference → |
| Python 2 → 3: tuple parameters | Tuple unpacking directly in function parameters is removed. Tuple values and unpacking assignments remain supported. | Replace a tuple parameter with a named parameter, then unpack it inside the function. Check nested parameter patterns and callers. Official PEP 3113 → |
| Python 3.10 | Deprecated collections ABC aliases are removed from collections. | Import affected interfaces from collections.abc and check older packages. Official reference → |
| Python 3.12 | distutils and imp are removed from the standard library. | Update build tooling and import handling; check native-extension and wheel availability. Official reference → |
| Python 3.13 | Older standard-library modules including cgi, cgitb, crypt and telnetlib are removed. | Select reviewed replacements and test CGI, authentication and network behaviour. Official reference → |
| Python 3.14 | Annotations are evaluated lazily by default; multiprocessing changes its default start method on relevant platforms. | Check annotation introspection, worker initialization, shared state and process startup. Official reference → |
Tuple parameters: Python 2 → Python 3
The tuple itself is not removed. The change is where it can be unpacked: Python 3 does not allow an unpacking pattern in a function parameter list.
Python 2
def process((name, value)):
return name, valuePython 3
def process(pair):
name, value = pair
return name, valuePEP 3113 — removal of tuple parameter unpacking
These are selected checkpoints, not a complete compatibility list. The project uses the actual source and target versions and all relevant intervening release notes. Deprecated APIs and removed APIs are tracked separately.
Shell upgrades are also utility upgrades.
Which shell?Confirm the shebang and execution method. /bin/sh may be a different implementation on the new OS; Bash arrays, [[ tests and process substitution are not universally portable POSIX sh syntax.
Which tools?GNU and BSD tools differ in options and output. Check sed editing flags, date formats, find expressions, awk dialects and commands whose output is parsed by other scripts.
Job environmentCheck PATH, working directory, locale, umask, credentials, permissions, signal handling and exit statuses under cron, systemd or the actual scheduler—not only an interactive terminal.
Safe behaviourReview quoting, whitespace in filenames, temporary files and pipeline failures. Changes to error handling are tested against the workflow; set -e is not a substitute for understanding failure paths.
Safety · traceability · milestone payments
Prove the job still does its job.
Agree the inputs, outputs, database effects and failure behaviour before changing the code. Each milestone has defined deliverables, acceptance checks and a payment amount; you approve the result before that milestone's payment and the next stage.
01
Audit & map
Required. $100, fully credited toward the service you choose. Trace entry points, modules, jobs, database adapters and external commands. Agree target versions and scope.
02
Adapt
Upgrade or port the selected code on a separate copy. Record dependency and configuration changes.
03
Test
Compare outputs, data changes, error handling and representative performance against the original.
04
Switch
Coordinate traffic or job ownership, final data sync and any required write pause after approval.
05
Hand over
Deliver code, version records, test results, deployment instructions and the rollback plan.
Keep production serving. Prevent duplicate jobs.
Parallel preparation keeps the current application running. Test copies must not send real messages, charge customers or run production jobs. At release, define which environment owns each worker, queue and scheduled task.
A compatible traffic switch can avoid planned service downtime. Data changes or stateful jobs may need an agreed pause. Rollback includes files and database writes, not just the old interpreter. Larger workloads can add workers or instances when locking, idempotency, shared state and database capacity support it.
Abandoned dependencies need a maintenance agreement. If a fork is required, repository access, licence obligations, ownership, future fixes and maintenance costs are agreed before work begins.
Questions before an interpreter upgrade
Is installing the new interpreter enough?
Sometimes. More often, the packages, native extensions, database connectors, paths and system utilities need attention too. The review identifies the actual scope.
Can you convert Perl to Python?
Yes. We scope the application or modules, map their dependencies and verify equivalent outputs and database effects. Language conversion is priced separately from a runtime upgrade.
Can you convert Python to Perl?
Yes. We preserve the agreed behaviour while selecting appropriate Perl modules and deployment conventions. The database access and integration work are included explicitly in the scope.
Why can database work cost more than the script changes?
The new OS can bring different client libraries, drivers, authentication and TLS behaviour. Rebuilding the access layer and proving transaction and data correctness can take more work than adapting language syntax.
Does the database engine have to change?
Not automatically. First we check whether a compatible connector can preserve the existing database. An engine or schema migration is a separate decision with its own data and rollback plan.
Can the application stay online?
It stays running while the new environment is prepared. Release continuity depends on compatible data, traffic switching and worker ownership. Any required pause is agreed before deployment.
Is the audit required?
Yes. The $100 audit is required for every job. It examines the interpreter, packages, database access and system utilities before the plan and price are agreed, and it is fully credited toward the service you choose.
How much does it cost?
Work starts from $99. Runtime drift, relevant code, packages, database access and utility changes determine the agreed price. Cross-language conversion and larger modernization are scoped separately.
How does this differ from EOL rescue?
EOL rescue preserves or moves an obsolete server environment. Interpreter upgrade work adapts the scripts, dependencies and backend connections to the target runtime. The services can be combined without charging twice for shared work.
Start with the scripts you already have
Keep the workflow. Update what it depends on.
Send the Perl, Python or shell version, OS, database and a description of the jobs or application. Tell us whether you want a runtime upgrade, selected modernization or Perl ↔ Python conversion. We will identify the work and explain the target environment and milestone plan.
For new clients: one free review covering one application on one runtime instance. Review terms →