Handle system detection like shell detection.

Makefile

@@ -46,10 +46,14 @@ standalone/vimpager: vimpager vimpager-version.txt ${SRC:=.uu} inc/* Makefile
 	@echo building $@
 	@${MKPATH} ${@D}
 	@sed \
-	    -e '/^ *\. .*inc\/prologue.sh"$$/{' \
+	    -e '/^\. .*inc\/prologue.sh/{' \
 	    -e     'r inc/prologue.sh' \
 	    -e     d \
 	    -e '}' \
+	    -e '/^\. .*inc\/platform.sh/{' \
+	    -e     'r inc/platform.sh' \
+	    -e     d \
+	    -e '}' \
 	    -e 's/^\( *\)# EXTRACT BUNDLED SCRIPTS HERE$$/\1extract_bundled_scripts/' \
 	    -e 's|^version=.*|version="'"`cat vimpager-version.txt`"' (standalone, shell=\$$(command -v \$$POSIX_SHELL))"|' \
 	    -e 's!^\( *\)runtime=.*$$!\1runtime='\''\$$tmp/runtime'\''!' \
@@ -75,7 +79,7 @@ standalone/vimcat: vimcat autoload/vimcat.vim vimcat-version.txt inc/prologue.sh
 	    -e '/^ *--cmd "set rtp^=\$$runtime" \\$$/d' \
 	    -e '/call vimcat#Init/i\'"$$nl"'--cmd "$$silent source $$0" \\' \
 	    -e 's/vimcat#\([^ ]*\)(/\1(/g' \
-	    -e '/^ *\. .*inc\/prologue.sh"$$/{' \
+	    -e '/^\. .*inc\/prologue.sh/{' \
 	    -e     'r inc/prologue.sh' \
 	    -e     d \
 	    -e '}' \
@@ -95,7 +99,7 @@ vimcat.uu: vimcat vimcat-version.txt
 	@printf "\t(cat <<'EOF') | do_uudecode > bin/vimcat\n" >> $@
 	@sed \
 	    -e 's|^version=.*|version="'"`cat vimcat-version.txt`"' (bundled, shell=\$$(command -v \$$POSIX_SHELL))"|' \
-	    -e '/^ *\. .*inc\/prologue.sh"$$/{' \
+	    -e '/^\. .*inc\/prologue.sh/{' \
 	    -e     'r inc/prologue.sh' \
 	    -e     d \
 	    -e '}' \
@@ -184,6 +188,7 @@ install: docs vimpager.configured vimcat.configured
 	sed -e '1{ s|.*|#!'"$$POSIX_SHELL"'|; }' \
 	    -e 's|\$$POSIX_SHELL|'"$$POSIX_SHELL|" \
 	    -e '/^ *\. .*inc\/prologue.sh"$$/d' \
+	    -e 's/^ *\. .*inc\/platform.sh"$$/'"`scripts/find_platform`"/ \
 	    -e 's|^version=.*|version="'"`cat $<-version.txt`"' (configured, shell='"$$POSIX_SHELL"')"|' \
 	    -e '/^# FIND REAL PARENT DIRECTORY$$/,/^# END OF FIND REAL PARENT DIRECTORY$$/d' \
 	    -e 's!^\( *\)runtime=.*!\1runtime='\''${PREFIX}/share/vimpager'\''!' \

inc/platform.sh

@@ -0,0 +1,73 @@
+#!/bin/sh
+
+# This file is used to set some variables acording to the system we are
+# running on.  It assumes a POSIX compatible shell.
+
+# Detect the operating system.
+case $(uname -s) in
+    Linux) linux=1 ;;
+    SunOS) solaris=1 ;;
+    Darwin) osx=1; bsd=1 ;;
+    CYGWIN*) cygwin=1; win32=1 ;;
+    MINGW*) msys=1; win32=1 ;;
+    MSYS*) msys=1; win32=1 ;;
+    OpenBSD) openbsd=1; bsd=1 ;;
+    FreeBSD) freebsd=1; bsd=1 ;;
+    NetBSD) netbsd=1; bsd=1 ;;
+    *) bsd=1 ;;
+esac
+
+# Find a suitble awk executable.
+if [ -n "$AWK" ] && command -v "$AWK" >/dev/null; then
+    :
+elif command -v gawk >/dev/null; then
+    AWK=gawk
+elif command -v nawk >/dev/null; then
+    AWK=nawk
+elif command -v mawk >/dev/null; then
+    AWK=mawk
+elif [ -x /usr/xpg4/bin/awk ]; then
+    AWK=/usr/xpg4/bin/awk
+elif command -v awk >/dev/null; then
+    AWK=awk
+else
+    echo "ERROR: No awk found!" >&2
+    exit 1
+fi
+
+# Find a suitable sed executable.
+if [ -n "$SED" ] && command -v "$SED" >/dev/null; then
+    :
+elif command -v gsed >/dev/null; then
+    SED=gsed
+elif [ -x /usr/xpg4/bin/sed ]; then
+    SED=/usr/xpg4/bin/sed
+elif command -v sed >/dev/null; then
+    SED=sed
+else
+    echo "ERROR: No sed found!" >&2
+    exit 1
+fi
+
+# Find a suitable head executable.
+if command -v ghead >/dev/null; then
+    HEAD=ghead
+else
+    HEAD=head
+fi
+
+# Check the syntax for head.
+if [ "$HEAD_SYNTAX" = new -o "$HEAD_SYNTAX" = old ]; then
+    :
+else
+    if [ "$(echo xx | "$HEAD" -n 1 2>/dev/null)" = xx ]; then
+        HEAD_SYNTAX=new
+    else
+        if ! "$HEAD" -1 -- "$0" >/dev/null 2>&1; then
+            HEAD_NO_DOUBLE_DASH=1
+        fi
+        HEAD_SYNTAX=old
+    fi
+fi
+
+# vim: sw=4 et tw=0:

scripts/find_platform

@@ -0,0 +1,30 @@
+#!/bin/sh
+
+. inc/platform.sh
+
+# The backslash has to be put here 4 times: foctor two to get past the initial
+# shell quoting, another factor two because it is used in the replacement
+# string for sed.  This yields one backslash that can escape the single quote
+# in the configured vimpager script.
+AWK=$(echo "$AWK" | sed "s/'/'\\\\''/g")
+SED=$(echo "$SED" | sed "s/'/'\\\\''/g")
+
+# The final sed is used to escape special characters for the sed command in
+# the makefile, where the output will be used.
+echo \
+    ${bsd:+bsd=$bsd} \
+    ${cygwin:+cygwin=$cygwin} \
+    ${freebsd:+freebsd=$freebsd} \
+    ${linux:+linux=$linux} \
+    ${msys:+msys=$msys} \
+    ${netbsd:+netbsd=$netbsd} \
+    ${openbsd:+openbsd=$openbsd} \
+    ${osx:+osx=$osx} \
+    ${solaris:+solaris=$solaris} \
+    ${win32:+win32=$win32} \
+    "AWK='$AWK'" \
+    "SED='$SED'" \
+    ${HEAD_SYNTAX:+HEAD_SYNTAX=$HEAD_SYNTAX} \
+    | sed -e 's/\\/\\\\/g' -e 's/|/\|/g'
+
+# vim: sw=4 et tw=0:

vimpager

@@ -27,7 +27,8 @@ done
 project_dir=`dirname "$link"`
 # END OF FIND REAL PARENT DIRECTORY
 
-. "$project_dir/inc/prologue.sh"
+. "$project_dir/inc/prologue.sh" # Hopefully we're now POSIX.
+. "$project_dir/inc/platform.sh"
 
 [ -n "$ZSH_VERSION" ] && emulate -R sh 2>/dev/null # force zsh into full POSIX
 
@@ -36,19 +37,6 @@ runtime='$project_dir'
 vimcat='$project_dir/vimcat'
 system_vimpagerrc='$project_dir/vimpagerrc'
 
-case "$(uname -s)" in
-    Linux) linux=1 ;;
-    SunOS) solaris=1 ;;
-    Darwin) osx=1; bsd=1 ;;
-    CYGWIN*) cygwin=1; win32=1 ;;
-    MINGW*) msys=1; win32=1 ;;
-    MSYS*) msys=1; win32=1 ;;
-    OpenBSD) openbsd=1; bsd=1 ;;
-    FreeBSD) freebsd=1; bsd=1 ;;
-    NetBSD) netbsd=1; bsd=1 ;;
-    *) bsd=1 ;;
-esac
-
 main() {
     # if no args and no stdin, display usage
     if [ $# -eq 0 -a -t 0 ]; then
@@ -219,12 +207,12 @@ main() {
 
         # squeeze blank lines if option was specified, Ubuntu man with /usr/bin/pager does this
         if [ "${squeeze_blank_lines:-0}" -eq 1 ]; then
-                sed -e '/^[ 	]*$/{
-                    N
-                    /^[ 	]*\n[ 	]*$/D
-                }' < "${tempfile:-$file}" > "$tmp/$filename.work"
-                tempfile=$tmp/$filename
-                mv -f -- "$tempfile.work" "$tempfile"
+            sed -e '/^[ 	]*$/{
+                N
+                /^[ 	]*\n[ 	]*$/D
+            }' < "${tempfile:-$file}" > "$tmp/$filename.work"
+            tempfile=$tmp/$filename
+            mv -f -- "$tempfile.work" "$tempfile"
         fi
 
         # dumb man detection when the pstree heuristic fails
@@ -639,38 +627,12 @@ Press ',h' for a summary of keystrokes in the program.
 EOF
 }
 
-if command -v gawk >/dev/null; then
-    _awk=gawk
-elif command -v nawk >/dev/null; then
-    _awk=nawk
-elif command -v mawk >/dev/null; then
-    _awk=mawk
-elif [ -x /usr/xpg4/bin/awk ]; then
-    _awk=/usr/xpg4/bin/awk
-elif command -v awk >/dev/null; then
-    _awk=awk
-else
-    echo "ERROR: No awk found!" >&2
-    quit 1
-fi
-
 awk() {
-    command "$_awk" "$@"
+    command "$AWK" "$@"
 }
 
-if command -v gsed >/dev/null; then
-    _sed=gsed
-elif [ -x /usr/xpg4/bin/sed ]; then
-    _sed=/usr/xpg4/bin/sed
-elif command -v sed >/dev/null; then
-    _sed=sed
-else
-    echo "ERROR: No sed found!" >&2
-    quit 1
-fi
-
 sed() {
-    command "$_sed" "$@"
+    command "$SED" "$@"
 }
 
 
@@ -724,20 +686,6 @@ awk_grep_E_q() {
     ' "$@"
 }
 
-if command -v ghead >/dev/null; then
-    _head=ghead
-else
-    _head=head
-fi
-
-if [ "$(echo xx | head -n 1 2>/dev/null)" = "xx" ]; then
-    _head_syntax=new
-else
-    if ! head -1 -- "$0" >/dev/null 2>&1; then
-        _head_no_double_dash=1
-    fi
-fi
-
 head() {
     _lines=
     case "$1" in
@@ -747,13 +695,13 @@ head() {
     esac
 
     if [ -z "$_lines" ]; then
-        command "$_head" "$@"
-    elif [ "$_head_syntax" = "new" ]; then
-        command "$_head" -n $_lines -- "$@"
-    elif [ -z "$_head_no_double_dash" ]; then
-        command "$_head" -$_lines -- "$@"
+        command "$HEAD" "$@"
+    elif [ "$HEAD_SYNTAX" = "new" ]; then
+        command "$HEAD" -n $_lines -- "$@"
+    elif [ -z "$HEAD_NO_DOUBLE_DASH" ]; then
+        command "$HEAD" -$_lines -- "$@"
     else
-        command "$_head" -$_lines "$@"
+        command "$HEAD" -$_lines "$@"
     fi
 }