1#!/bin/sh 2# 3# This script takes a filename as input and writes the current date to the 4# file. If the file already exists, it will not be overwritten unless the '-f' 5# (or '--force') flag is given. 6# 7# This script demonstrates several types of shFlags functionality. 8# - declaration of the FLAGS_HELP variable to customize the help output 9# - direct calling of the flags_help() function for script controlled usage 10# output 11# - handling of non-flag type command-line arguments that follow the flags 12# 13# Try the following: 14# $ ./write_date.sh now.out 15# $ cat now.out 16# 17# $ ./write_date.sh now.out 18# $ cat now.out 19# 20# $ ./write_date.sh -f now.out 21# $ cat now.out 22 23# source shflags 24. ../src/shflags 25 26# configure shflags 27DEFINE_boolean 'force' false 'force overwriting' 'f' 28FLAGS_HELP="USAGE: $0 [flags] filename" 29 30 31write_date() 32{ 33 date >"$1" 34} 35 36die() 37{ 38 [ $# -gt 0 ] && echo "error: $@" >&2 39 flags_help 40 exit 1 41} 42 43 44# parse the command-line 45FLAGS "$@" || exit 1 46eval set -- "${FLAGS_ARGV}" 47 48# check for filename 49[ $# -gt 0 ] || die 'filename missing' 50filename=$1 51 52[ -f "${filename}" -a ${FLAGS_force} -eq ${FLAGS_FALSE} ] \ 53 && die 'filename exists; not overwriting' 54write_date "${filename}" 55