install-script

#!/bin/bash

# usage: install-script [opt]... srcfile dst

inopts=true

owner=
group=
mode=
flags=()
noclobber=

replace_mode=assign
replacement_keys=()
replacement_values=()

error()
{
    cat >&2 <<EOF
$0: $@
usage: $(basename "$0") [<opt>]... [--] <srcfile> <dst>

Options:
   -o owner        set owner of dstfile
   -g group        set group ownership of dstfile
   -m mode         set mode of dstfile
   -n              no-clobber
   -Z context      set SE-Linux context and rule for dstfile
   -p              preserve timestamp on dstfile
   -D              create parent directories of dstfile
   -M mode         replacement mode: assign (default), ref, sed
   -R key=value... apply replacements, e.g.
                      "s/^key=.*/key=value/" (assign mode)

When using pattern replacement, srcfile is rewritten to a temporary
before being installed to dstfile.  The replacment modes correspond
to:

   assign: replace shell script variable assignments such as
      "key=rest-of-line" with "key=value"

   ref: replace shell script variable references such as
      "\${key}" with "value"

   sed: replace using arbitrary sed pattern/value expressions

The final mode specification applies to all replacements.

Installation is handled by the regular "install" utility, which
supports a target filepath or a target directory path for the
destination argument. However, this script does not support the 

EOF
    exit 1
}

while [[ $# -gt 0 ]] && [[ -n "$inopts" ]]
do
    case "$1" in
	-o) owner="$2" ; shift 2 ;;
	-g) group="$2" ; shift 2 ;;
	-m) mode="$2" ; shift 2 ;;
        -n) noclobber=true ; shift 1 ;;
	-Z) context="$2" ; shift 2 ;;
	-p|-D) flags+=( "$1" ) ;  shift 1 ;;
	-M)
	    case "$2" in
		assign|ref|sed)
		    replace_mode="$2"
		    ;;
		*)
		    error Unrecognized replacement mode "\"$2\"".
		    ;;
	    esac
	    shift 2
	    ;;
	-R) 
	    shift 1
	    inreplace=true
	    while [[ $# -gt 0 ]] && [[ -n "$inreplace" ]]
	    do
		case "$1" in
		    --) inreplace= ; shift 1 ;;
		    ?*=*)
			key="${1%%=*}"
			value="${1##${key}=}"
			key="${key//\//\\/}"
			value="${value//\//\\/}"

			replacement_keys+=( "$key" )
			replacement_values+=( "$value" )

			shift 1
			;;
		    *) inreplace= ;;
		esac
	    done
	    ;;
	-*)
	    error Unrecognized option "\"$1\"".
	    exit 1
	    ;;
	--) inopts= ; shift 1 ;;
	*) inopts= ;;
    esac
done

[[ $# -lt 2 ]] && error Require srcfile and dst arguments after options.
[[ ! -r "$1" ]] && error Cannot read srcfile "\"$1\"".

srcfile="$1"
dstfile="$2"

[[ -n "$owner" ]] && flags+=( -o "$owner" )
[[ -n "$group" ]] && flags+=( -g "$group" )
[[ -n "$mode" ]] && flags+=( -m "$mode" )
if [[ -n "$context" ]]
then
    #flags+=( -Z "$context" )
    semanage fcontext --add --type "$context" "$dstfile" || error Could not install SE-Linux context "$context" for "$dstfile"
fi

TMP=

cleanup()
{
    [[ -n "$TMP" ]] && [[ -e "$TMP" ]] && rm -f "$TMP"
}

trap cleanup 0

replacements=()

for i in ${!replacement_keys[@]}
do
    case "${replace_mode}" in
	assign) replacements+=( -e "s/^${replacement_keys[$i]}=.*/${replacement_keys[$i]}=\"${replacement_values[$i]}\"/" ) ;;
	ref) replacements+=( -e "s/\${${replacement_keys[$i]}}/${replacement_values[$i]}/g" ) ;;
	sed) replacements+=( -e "s/${replacement_keys[$i]}/${replacement_values[$i]}/g" ) ;;
    esac
done

#echo --  "${replacements[@]}"

if [[ "$noclobber" = "true" ]] && [[ -r "$dstfile" ]]
then
    echo Skipping installation that would overwrite existing "$dstfile"
    exit 0
fi

if [[ "${#replacements[@]}" -gt 0 ]]
then
    TMP=$(mktemp)
    [[ -w "$TMP" ]] || error Could not create temporary file.
    sed "${replacements[@]}" < "$srcfile" > "$TMP" && {
	touch -r "$srcfile" "$TMP"
	install "${flags[@]}" "$TMP" "$dstfile"
    } || {
	echo replacement "${replacements[@]}" failed >&2
	exit 1
    }
else
    install "${flags[@]}" "$srcfile" "$dstfile"
fi