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 27 DEFINE_boolean 'force' false 'force overwriting' 'f' 28 FLAGS_HELP="USAGE: $0 [flags] filename" 29 30 31 write_date() 32 { 33 date >"$1" 34 } 35 36 die() 37 { 38 [ $# -gt 0 ] && echo "error: $@" >&2 39 flags_help 40 exit 1 41 } 42 43 44 # parse the command-line 45 FLAGS "$@" || exit 1 46 eval set -- "${FLAGS_ARGV}" 47 48 # check for filename 49 [ $# -gt 0 ] || die 'filename missing' 50 filename=$1 51 52 [ -f "${filename}" -a ${FLAGS_force} -eq ${FLAGS_FALSE} ] \ 53 && die 'filename exists; not overwriting' 54 write_date "${filename}" 55
