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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 # This allows us to work with the newline character:
 define newline
 
 
 endef
 newline := $(newline)
 
 # nl-escape
 #
 # Usage: escape = $(call nl-escape[,escape])
 #
 # This is used as the common way to specify
 # what should replace a newline when escaping
 # newlines; the default is a bizarre string.
 #
 nl-escape = $(if $(1),$(1),m822df3020w6a44id34bt574ctac44eb9f4n)
 
 # escape-nl
 #
 # Usage: escaped-text = $(call escape-nl,text[,escape])
 #
 # GNU make's $(shell ...) function converts to a
 # single space each newline character in the output
 # produced during the expansion; this may not be
 # desirable.
 #
 # The only solution is to change each newline into
 # something that won't be converted, so that the
 # information can be recovered later with
 # $(call unescape-nl...)
 #
 escape-nl = $(subst $(newline),$(call nl-escape,$(2)),$(1))
 
 # unescape-nl
 #
 # Usage: text = $(call unescape-nl,escaped-text[,escape])
 #
 # See escape-nl.
 #
 unescape-nl = $(subst $(call nl-escape,$(2)),$(newline),$(1))
 
 # shell-escape-nl
 #
 # Usage: $(shell some-command | $(call shell-escape-nl[,escape]))
 #
 # Use this to escape newlines from within a shell call;
 # the default escape is a bizarre string.
 #
 # NOTE: The escape is used directly as a string constant
 #       in an `awk' program that is delimited by shell
 #       single-quotes, so be wary of the characters
 #       that are chosen.
 #
 define shell-escape-nl
 awk 'NR==1 {t=$$0} NR>1 {t=t "$(nl-escape)" $$0} END {printf t}'
 endef
 
 # shell-unescape-nl
 #
 # Usage: $(shell some-command | $(call shell-unescape-nl[,escape]))
 #
 # Use this to unescape newlines from within a shell call;
 # the default escape is a bizarre string.
 #
 # NOTE: The escape is used directly as an extended regular
 #       expression constant in an `awk' program that is
 #       delimited by shell single-quotes, so be wary
 #       of the characters that are chosen.
 #
 # (The bash shell has a bug where `{gsub(...),...}' is
 #  misinterpreted as a brace expansion; this can be
 #  overcome by putting a space between `{' and `gsub').
 #
 define shell-unescape-nl
 awk 'NR==1 {t=$$0} NR>1 {t=t "\n" $$0} END { gsub(/$(nl-escape)/,"\n",t); printf t }'
 endef
 
 # escape-for-shell-sq
 #
 # Usage: embeddable-text = $(call escape-for-shell-sq,text)
 #
 # This function produces text that is suitable for
 # embedding in a shell string that is delimited by
 # single-quotes.
 #
 escape-for-shell-sq =  $(subst ','\'',$(1))
 
 # shell-sq
 #
 # Usage: single-quoted-and-escaped-text = $(call shell-sq,text)
 #
 shell-sq = '$(escape-for-shell-sq)'
 
 # shell-wordify
 #
 # Usage: wordified-text = $(call shell-wordify,text)
 #
 # For instance:
 #
 #  |define text
 #  |hello
 #  |world
 #  |endef
 #  |
 #  |target:
 #  |    echo $(call shell-wordify,$(text))
 #
 # At least GNU make gets confused by expanding a newline
 # within the context of a command line of a makefile rule
 # (this is in constrast to a `$(shell ...)' function call,
 # which can handle it just fine).
 #
 # This function avoids the problem by producing a string
 # that works as a shell word, regardless of whether or
 # not it contains a newline.
 #
 # If the text to be wordified contains a newline, then
 # an intrictate shell command substitution is constructed
 # to render the text as a single line; when the shell
 # processes the resulting escaped text, it transforms
 # it into the original unescaped text.
 #
 # If the text does not contain a newline, then this function
 # produces the same results as the `$(shell-sq)' function.
 #
 shell-wordify = $(if $(findstring $(newline),$(1)),$(_sw-esc-nl),$(shell-sq))
 define _sw-esc-nl
 "$$(echo $(call escape-nl,$(shell-sq),$(2)) | $(call shell-unescape-nl,$(2)))"
 endef
 
 # is-absolute
 #
 # Usage: bool-value = $(call is-absolute,path)
 #
 is-absolute = $(shell echo $(shell-sq) | grep -q ^/ && echo y)
 
 # lookup
 #
 # Usage: absolute-executable-path-or-empty = $(call lookup,path)
 #
 # (It's necessary to use `sh -c' because GNU make messes up by
 #  trying too hard and getting things wrong).
 #
 lookup = $(call unescape-nl,$(shell sh -c $(_l-sh)))
 _l-sh = $(call shell-sq,command -v $(shell-sq) | $(call shell-escape-nl,))
 
 # is-executable
 #
 # Usage: bool-value = $(call is-executable,path)
 #
 # (It's necessary to use `sh -c' because GNU make messes up by
 #  trying too hard and getting things wrong).
 #
 is-executable = $(call _is-executable-helper,$(shell-sq))
 _is-executable-helper = $(shell sh -c $(_is-executable-sh))
 _is-executable-sh = $(call shell-sq,test -f $(1) -a -x $(1) && echo y)
 
 # get-executable
 #
 # Usage: absolute-executable-path-or-empty = $(call get-executable,path)
 #
 # The goal is to get an absolute path for an executable;
 # the `command -v' is defined by POSIX, but it's not
 # necessarily very portable, so it's only used if
 # relative path resolution is requested, as determined
 # by the presence of a leading `/'.
 #
 get-executable = $(if $(1),$(if $(is-absolute),$(_ge-abspath),$(lookup)))
 _ge-abspath = $(if $(is-executable),$(1))
 
 # get-supplied-or-default-executable
 #
 # Usage: absolute-executable-path-or-empty = $(call get-executable-or-default,variable,default)
 #
 define get-executable-or-default
 $(if $($(1)),$(call _ge_attempt,$($(1)),$(1)),$(call _ge_attempt,$(2)))
 endef
 _ge_attempt = $(or $(get-executable),$(call _gea_err,$(2)))
 _gea_err  = $(if $(1),$(error Please set '$(1)' appropriately))

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