examples/scripts.v2/repeat

   1 #! /bin/bash
   2 #
   3 # original from:
   4 # repeat: repeat a command.
   5 # @(#) repeat.ksh 1.1 93/06/03
   6 # 90/05 john h. dubois iii (john@armory.com)
   7 # 90/11 added help
   8 # 93/06/03 Added s, h, p, and v options
   9 #
  10 # conversion to bash v2 syntax done by Chet Ramey
  11
  12 istrue()
  13 {
  14         test 0 -ne "$1"
  15 }
  16
  17 isfalse()
  18 {
  19         test 0 -eq "$1"
  20 }
  21
  22 phelp()
  23 {
  24 echo "$name: repeatedly execute a command line.
  25 $Usage
  26 commandline is executed once for each integer from startcount through endcount
  27 inclusive.  The default for startcount is 1 if a positive endcount or no
  28 endcount is given, and -1 if a negative endcount is given.  A count
  29 parameter consisting of a single number is taken to be an endcount.  If
  30 only an endcount is given and it is positive, commandline is executed
  31 endcount times.  endcount may be less than startcount.  If no endcount is
  32 given (e.g. a count parameter of \"10-\"), commandline execution repeats
  33 indefinitely with the iteration variable incrementing in a positive
  34 direction.  A count parameter of consisting of \"-\" will repeat
  35 indefinitely starting with 1.
  36
  37 Note that quoting and variables in commandline are interpreted twice, once
  38 when it is passed to the repeat command, and once when it is actually executed.
  39
  40 The iteration variable is \"count\".  If \$count is used in commandline, make
  41 sure it is quoted with ' or \.
  42
  43 Options:
  44 -h: Print this help.
  45 -p: Print value of iteration variable on stderr before each iteration.
  46 -s <sec>: sleep for <sec> seconds after each iteration except the last.
  47 -v: Print start and end values before beginning."
  48 }
  49
  50 name=${0##*/}
  51 Usage="Usage: repeat [-hpv] [-s <sec>] [[startcount]-][endcount] command [arg ...]"
  52
  53 typeset -i count=1 forever=0 sleep=0 print=0 verbose=0
  54
  55 while getopts :0123456789hpvs: opt; do
  56     case $opt in
  57     h) phelp; exit 0;;
  58     s) sleep=$OPTARG || exit 1;;
  59     p) print=1;;
  60     v)verbose=1;;
  61     [0-9]) break;;
  62     +?) echo "$name: options should not be preceded by a '+'." 1>&2; exit 2;;
  63     ?)  echo "$name: $OPTARG: bad option.  Use -h for help." 1>&2; exit 2;;
  64     esac
  65 done
  66
  67 # remove args that were options
  68 shift $((OPTIND-1))
  69
  70 if [ $# -lt 2 ]; then
  71     echo -e "$Usage\nUse -h for help." 1>&2
  72     exit 2
  73 fi
  74
  75 case "$1" in
  76 -[0-9]*-|[0-9]*-)
  77     # Start value only
  78     count=${1%-}
  79     forever=1
  80     end="-1";
  81     ;;
  82 -[0-9]*-[0-9]*|[0-9]*-[0-9]*)
  83     # Start and end value
  84     s=${1%-}
  85     end=${s##[0-9]*-}
  86     count=${s%-$end}
  87     ;;
  88 -[0-9]*|[0-9]*)
  89     end=$1
  90     case "$end" in
  91     -\*)        count=-1;;
  92     esac
  93     ;;
  94 -)
  95     forever=1
  96     end="-1";
  97     ;;
  98 *)
  99     echo "$name: bad count parameter: $1" 1>&2
 100     exit 1
 101     ;;
 102 esac
 103
 104 shift
 105
 106 [ -z "$end" ] && [ $count -le "$end" ] && increment=1 || increment=-1
 107
 108 istrue $verbose && echo "start=$count end=$end" 1>&2
 109
 110 # Need to do this here so that up to this point, -0 will keep the leading -
 111 # and end will not be 0 if no value assigned
 112 typeset -i end
 113
 114 let end+=increment      # make loop inclusive of original endcount
 115
 116 while istrue $forever || [ $count -ne $end ]; do
 117     istrue $print && echo $count 1>&2
 118     eval "$@"
 119     istrue $sleep && sleep $sleep
 120     let count+=increment
 121 done