shebangtron

Update the python interpreter path of EUPS installed products.

Usage

curl -sSL https://raw.githubusercontent.com/lsst/shebangtron/master/shebangtron | python

Overview

Recent releases of OSX include a feature called "System Integrity Protection" or "SIP".

See DMTN-001: Porting the stack to OS X El Capitan

TL;DR - SIP breaks the common idiom of using /usr/bin/env in the shebang line of python scripts.

A solution is to use the fully qualified path to the desired python interpreter in the shebang line. This can be automatically done as part of a build/install process but the build time path is unlikely to work when exporting software (Eg., moving it to another system) from the build environment. This requires that either a package manager (such as conda-build) handles this as part of a post-install hook or manual action on the part of the end-user. As EUPS does not support post-install hooks/scripts, a manual step is required.

Prerequisites

A working EUPS environment is needed to supply the eups utility and define the env var EUPS_PATH must be defined. For an newinstall.sh based env, sourcing one of the generated setup scripts is sufficient. Eg.,

source loadLSST.bash
curl -sSL https://raw.githubusercontent.com/lsst/shebangtron/master/shebangtron | python

Nitty-gritty

shebangtron will attempt to fixup the shebang line of all files that have write permissions under the path ${EUPS_PATH}/$(eups flavor). This is not presently configurable beyond setting the value of EUPS_PATH.

The intent to keep this script easily usable as a single file that can be curl'd and piped to python rather than installed as a pypi or conda package.

The script is composed of (modified) snippets extracted from conda-build and merged into a single script. This was necessary to avoid requiring the end-user to both install conda-build to use as a library and a separate "fixup" script. In addition, changes to the permission handling logic were needed.