conda2pip.sh

#!/usr/bin/env bash

function usage {
    echo "$0 [options] <conda environment file>"
    echo
    echo "  Options:"
    echo "       -h shows this message"
    echo
    echo
}

function error {
    echo "$2" >&2
    usage
    exit $1
}


if [[ $# -ne 1 ]]; then
    error 1 "Missing required argument: <conda environment file>"
fi

INPUT_FILE="$1"
echo "$INPUT_FILE"
if [[ ! -f "$INPUT_FILE" ]]; then
    error 2 "Conda environment file not found"
fi

# create an empty the requirements file
echo "" > requirements.txt
CONDA_BLOCK=0
PIP_BLOCK=0

CONDA_BLOCK_PATTERN="^dependencies:$"
PIP_BLOCK_PATTERN="^- pip:$"

# read every non-empty line
while IFS="" read -r line || [ -n "$line" ]; do
    # trim string
    entry=$(echo "${line}" | sed -e 's/^[ \t]*//')
    [[ $entry =~ $CONDA_BLOCK_PATTERN ]] && echo "Conda dependencies block found " && CONDA_BLOCK=1
    [[ $CONDA_BLOCK == 0 ]] && continue

    # Skip non dependency lines
    [[ $entry != -* ]] && echo "skipping '$line' line" &&  continue
    if [[ $entry =~ $PIP_BLOCK_PATTERN ]]; then
        PIP_BLOCK=1
        echo "pip dependencies block found"
        continue
    fi

    if [[ $PIP_BLOCK == 1 ]]; then
        entry=$(echo "${entry}" | sed -e 's/^[ -]*//')
        echo "${entry}" >> requirements.txt
    else
        # remove the '-' and space before the package name
        entry=$(echo "${entry}" | sed -e 's/^[ -]*//')

        regex="^([ -]*)([a-zA-Z_-]*)(=.*)?"
        if [[ $entry =~ $regex ]]; then
            package="${BASH_REMATCH[2]}"
            version="${BASH_REMATCH[3]}"

            # echo correct structure to requirements file
            if [[ ! -z "${version}" ]]; then
                echo "${package}=${version}" >> requirements.txt
            else
                echo "${package}" >> requirements.txt
            fi
        fi
    fi
done <<< "$(cat $INPUT_FILE)"