#!/bin/sh
#
# This script takes a filename as input and writes the current date to the
# file. If the file already exists, it will not be overwritten unless the '-f'
# (or '--force') flag is given.
#
# This script demonstrates several types of shFlags functionality.
# - declaration of the FLAGS_HELP variable to customize the help output
# - direct calling of the flags_help() function for script controlled usage
#   output
# - handling of non-flag type command-line arguments that follow the flags
#
# Try the following:
# $ ./write_date.sh now.out
# $ cat now.out
#
# $ ./write_date.sh now.out
# $ cat now.out
#
# $ ./write_date.sh -f now.out
# $ cat now.out

# source shflags
source ../src/shflags

# configure shflags
DEFINE_boolean 'force' false 'force overwriting' 'f'
setglobal FLAGS_HELP = ""USAGE: $0 [flags] filename""


proc write_date
{
  date >$1
}

proc die
{
  test $Argc -gt 0 && echo "error: $ifsjoin(Argv)" > !2
  flags_help
  exit 1
}


# parse the command-line
FLAGS @Argv || exit 1
eval set -- $(FLAGS_ARGV)

# check for filename
test $Argc -gt 0 || die 'filename missing'
setglobal filename = $1

test -f $(filename) -a $(FLAGS_force) -eq $(FLAGS_FALSE) \
    && die 'filename exists; not overwriting'
write_date $(filename)