req2abs.awk

#!/usr/bin/env awk -f
function rel2abs(req, dir, root)
{
    "readlink --canonicalize " root|getline res
    "sh -c \"cd "  dir  " && readlink --canonicalize "  req  "\""|getline resolved
    gsub(res, "", resolved)
    gsub(/^\//,"", resolved)
    return resolved
}

{
    qs="('|\")"
    if (match($0, "require\\s+" qs "(\\..*)" qs, m) != 0)
    {
        sub (/require (.*)/, "require '" rel2abs(m[2], DIR, ROOT) "'")
    }
    print $0
}

req2abs.sh

#! /usr/bin/env sh

ROOT=$(readlink --canonicalize ${1})
TOFIX=$(readlink --canonicalize ${2})
DIR=$(dirname $TOFIX)

awk -i inplace -v DIR="$DIR" -v ROOT="$ROOT" -f $(dirname $0)/req2abs.awk $TOFIX

running.txt

# To run the scripts (example):

ag --coffee "require" | xargs -n 1 req2abs.sh assets/source
ag --sass "url" | xargs -n 1 url2abs.sh assets/source

url2abs.awk

#!/usr/bin/env awk -f
function rel2abs(req, dir, root)
{
    "readlink --canonicalize " root|getline res
    "sh -c \"cd "  dir  " && readlink --canonicalize "  req  "\""|getline resolved
    gsub(res, "", resolved)
    gsub(/^\//,"", resolved)
    return resolved
}

{
    if (match($0, "url\\s*\\((\\.[^)]*)\\)", m) != 0)
    {
        sub (/url\s*([^)]*))/, "url(" rel2abs(m[1], DIR, ROOT) ")")
    }
    print $0
}

url2abs.sh

#! /usr/bin/env sh

ROOT=$(readlink --canonicalize ${1})
TOFIX=$(readlink --canonicalize ${2})
DIR=$(dirname $TOFIX)

awk -i inplace -v DIR="$DIR" -v ROOT="$ROOT" -f $(dirname $0)/url2abs.awk $TOFIX