update-usage-msg.sh

#!/bin/sh
#
# Update usage-msg.h from send-echo-request.c comment iff it has
# changed, so that make only rebuilds on actual changes.

set -e
cd "$(dirname "$0")"

test -f send-echo-request.c

cat>usage-msg.h.new<<EOF
#if 0
 | DO NOT EDIT THIS FILE.
 | It was generated by the $(basename "$0") script
 | from the comments in the send-echo-request.c file
 | which must end with the first " */" line in the file,
 | start with a line beginning with " * Usage: ", and
 | each line in between must be " *" or begin with " * ".
#endif

#ifndef USAGE_MSG_H
#define USAGE_MSG_H

#define USAGE_MSG "" \\
EOF

cat send-echo-request.c \
    | sed '/^ \*\/$/,$d' \
    | sed -n '/^ \* Usage: /,$p' \
    | sed -e 's/^ \*$//' -e 's/^ \* //' \
    | sed -e 's/^/  "/' -e 's/$/\\n" \\/' \
    >> usage-msg.h.new

cat>>usage-msg.h.new<<EOF
  ""

#endif /* ! USAGE_MSG_H */
EOF

if test -f "usage-msg.h"
then
    if cmp -s "usage-msg.h.new" "usage-msg.h"
    then
	rm "usage-msg.h.new"
    else
	mv -f "usage-msg.h.new" "usage-msg.h"
    fi
else
    mv -f "usage-msg.h.new" "usage-msg.h"
fi