examples/functions/substr

   1 #
   2 # substr -- a function to emulate the ancient ksh builtin
   3 #
   4
   5 #
   6 # -l == shortest from left
   7 # -L == longest from left
   8 # -r == shortest from right (the default)
   9 # -R == longest from right
  10
  11 substr()
  12 {
  13         local flag pat str
  14         local usage="usage: substr -lLrR pat string or substr string pat"
  15
  16         case "$1" in
  17         -l | -L | -r | -R)
  18                 flag="$1"
  19                 pat="$2"
  20                 shift 2
  21                 ;;
  22         -*)
  23                 echo "substr: unknown option: $1"
  24                 echo "$usage"
  25                 return 1
  26                 ;;
  27         *)
  28                 flag="-r"
  29                 pat="$2"
  30                 ;;
  31         esac
  32
  33         if [ "$#" -eq 0 ] || [ "$#" -gt 2 ] ; then
  34                 echo "substr: bad argument count"
  35                 return 2
  36         fi
  37
  38         str="$1"
  39
  40         #
  41         # We don't want -f, but we don't want to turn it back on if
  42         # we didn't have it already
  43         #
  44         case "$-" in
  45         "*f*")
  46                 ;;
  47         *)
  48                 fng=1
  49                 set -f
  50                 ;;
  51         esac
  52
  53         case "$flag" in
  54         -l)
  55                 str="${str#$pat}"               # substr -l pat string
  56                 ;;
  57         -L)
  58                 str="${str##$pat}"              # substr -L pat string
  59                 ;;
  60         -r)
  61                 str="${str%$pat}"               # substr -r pat string
  62                 ;;
  63         -R)
  64                 str="${str%%$pat}"              # substr -R pat string
  65                 ;;
  66         *)
  67                 str="${str%$2}"                 # substr string pat
  68                 ;;
  69         esac
  70
  71         echo "$str"
  72
  73         #
  74         # If we had file name generation when we started, re-enable it
  75         #
  76         if [ "$fng" = "1" ] ; then
  77                 set +f
  78         fi
  79 }