extract-manpages-environ

#!/usr/bin/env bash
#
# extract-manpages-environ v1.1
#
# Extract environment variable names from Linux manual pages
# (ensure that /usr/libexec/makewhatis has been executed)
#
# Written By:   Derek Callaway [decal (AT) sdf {D0T} org]
# Last Updated: Sat Apr 21 10:08:23 PDT 2018
# Tested On:    Ubuntu 16.04.3 LTS
#               Darwin 17.5.0 Darwin Kernel Version 17.5.0: Mon Mar  5 22:24:32 PST 2018; root:xnu-4570.51.1~1/RELEASE_X86_64 x86_64 i386
#

PAGER=cat

for m in $(man -k '' | awk -F\( '{print$1}')
  do declare -i aline="$(man -- $m | grep -n 'ENVIRONMENT' | tail -n 1 | awk -F: '{print$2}')"
  declare -a names=( )

  names+=$(PAGER=cat man most | tail -n +${aline} | egrep '^[ ]+[A-Z_, ]+$' | awk -F, '{print$1}')
  names+=$(PAGER=cat man most | tail -n +${aline} | egrep '^[ ]+[A-Z_, ]+$' | awk -F, '{print$2}')
  names+=$(PAGER=cat man most | tail -n +${aline} | egrep '^[ ]+[A-Z_, ]+$' | awk -F, '{print$3}')
  names+=$(PAGER=cat man most | tail -n +${aline} | egrep '^[ ]+[A-Z_, ]+$' | awk -F, '{print$4}')
done

exit 0